v0.6.0-beta.1

Add builder implementation similar to `LuaOptions` to set individual options.

.github/workflows/coverage.yml

@@ -0,0 +1,23 @@
+name: coverage
+on: [push]
+
+jobs:
+  test:
+    name: coverage
+    runs-on: ubuntu-latest
+    container:
+      image: xd009642/tarpaulin
+      options: --security-opt seccomp=unconfined
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Generate code coverage
+        run: |
+          cargo tarpaulin --verbose --features lua53,vendored,async,send,serialize --out xml --exclude-files benches --exclude-files tests --exclude-files build --exclude-files src/ffi
+
+      - name: Upload to codecov.io
+        uses: codecov/codecov-action@v1
+        with:
+          token: ${{secrets.CODECOV_TOKEN}}
+          fail_ci_if_error: false

.github/workflows/main.yml

@@ -7,141 +7,207 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        thing:
-        - stable
-        - macos-x86_64
-        - x86_64-msvc
+        os: [ubuntu-18.04, macos-latest, windows-latest]
+        rust: [stable]
+        lua: [lua54, lua53, lua52, lua51, luajit]
         include:
-        - thing: stable
+        - os: ubuntu-18.04
           target: x86_64-unknown-linux-gnu
-          rust: stable
-          os: ubuntu-latest
-        - thing: macos-x86_64
+        - os: macos-latest
           target: x86_64-apple-darwin
-          rust: stable
-          os: macos-latest
-        - thing: x86_64-msvc
+        - os: windows-latest
           target: x86_64-pc-windows-msvc
-          rust: stable-x86_64-msvc
-          os: windows-latest
     steps:
-    - uses: actions/checkout@v1
-    - name: Install Rust (rustup)
-      if: matrix.os != 'macos-latest'
-      run: rustup update ${{ matrix.rust }} --no-self-update && rustup default ${{ matrix.rust }}
-      shell: bash
-    - name: Install Lua (ubuntu)
-      if: matrix.os == 'ubuntu-latest'
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: ${{ matrix.rust }}
+        target: ${{ matrix.target }}
+        override: true
+    - name: Build ${{ matrix.lua }} vendored
       run: |
-        sudo apt-get update -y
+        cargo build --release --features "${{ matrix.lua }} vendored"
+        cargo build --release --features "${{ matrix.lua }} vendored async send serialize"
+      shell: bash
+    - name: Build ${{ matrix.lua }} pkg-config
+      if: ${{ matrix.os == 'ubuntu-18.04' && matrix.lua != 'lua54' }}
+      run: |
+        sudo apt-get update
         sudo apt-get install -y --no-install-recommends liblua5.3-dev liblua5.2-dev liblua5.1-0-dev libluajit-5.1-dev
-    - name: Install Rust (macos)
-      if: matrix.os == 'macos-latest'
+        cargo build --release --features "${{ matrix.lua }}"
+
+  build_aarch64_cross_macos:
+    name: Cross-compile to aarch64-apple-darwin
+    runs-on: macos-11.0
+    needs: build
+    strategy:
+      matrix:
+        lua: [lua54, lua53, lua52, lua51, luajit]
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        target: aarch64-apple-darwin
+        override: true
+    - name: Cross-compile
+      run: cargo build --target aarch64-apple-darwin --features "${{ matrix.lua }} async send serialize vendored"
+
+  build_aarch64_cross_ubuntu:
+    name: Cross-compile to aarch64-unknown-linux-gnu
+    runs-on: ubuntu-18.04
+    needs: build
+    strategy:
+      matrix:
+        lua: [lua54, lua53, lua52, lua51, luajit]
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        target: aarch64-unknown-linux-gnu
+        override: true
+    - name: Install ARM compiler toolchain
       run: |
-        curl https://sh.rustup.rs | sh -s -- -y
-        echo ::add-path::$HOME/.cargo/bin
-      shell: bash
-    - name: Install GCC (aarch64-linux)
-      run: |
-        sudo apt-get update -y
+        sudo apt-get update
         sudo apt-get install -y --no-install-recommends gcc-aarch64-linux-gnu libc6-dev-arm64-cross
-      if: matrix.thing == 'aarch64-linux'
       shell: bash
-    - run: rustup target add ${{ matrix.target }}
-    - name: Build (Lua 5.3/5.2/5.1 and LuaJIT vendored)
-      run: |
-        for FEATURE in lua53 lua52 lua51 luajit; do
-          echo "Building $FEATURE"
-          cargo build --target ${{ matrix.target }} --release --no-default-features --features "$FEATURE vendored"
-        done
-      shell: bash
-    - name: Build (Lua 5.3/5.2/5.1 and LuaJIT via pkg-config)
-      if: matrix.os == 'ubuntu-latest'
-      run: |
-        for FEATURE in lua53 lua52 lua51 luajit; do
-          echo "Building $FEATURE"
-          cargo build --target ${{ matrix.target }} --release --no-default-features --features $FEATURE
-        done
+    - name: Cross-compile
+      run: cargo build --target aarch64-unknown-linux-gnu --features "${{ matrix.lua }} async send serialize vendored"
       shell: bash
 
-  test_linux:
-    name: Test on Linux
-    runs-on: ubuntu-latest
+  build_armv7_cross_ubuntu:
+    name: Cross-compile to armv7-unknown-linux-gnueabihf
+    runs-on: ubuntu-18.04
     needs: build
+    strategy:
+      matrix:
+        lua: [lua54, lua53, lua52, lua51]
     steps:
-    - uses: actions/checkout@v1
-    - name: Install Rust
-      run: rustup update stable --no-self-update && rustup default stable
-      shell: bash
-    - name: Run tests (Lua 5.3 vendored)
-      run: cargo test --release --no-default-features --features "lua53 vendored"
-      shell: bash
-    - name: Run tests (Lua 5.2 vendored)
-      run: cargo test --release --no-default-features --features "lua52 vendored"
-      shell: bash
-    - name: Run tests (Lua 5.1 vendored)
-      run: cargo test --release --no-default-features --features "lua51 vendored"
-      shell: bash
-    - name: Run tests (LuaJIT vendored)
-      run: cargo test --release --no-default-features --features "luajit vendored"
-      shell: bash
-    - name: Run compile test (Lua 5.3)
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        target: armv7-unknown-linux-gnueabihf
+        override: true
+    - name: Install ARM compiler toolchain
       run: |
-        sudo apt-get update -y
-        sudo apt-get install -y --no-install-recommends liblua5.3-dev
-        cargo test --release --no-default-features --features "lua53 vendored" -- --ignored
+        sudo apt-get update
+        sudo apt-get install -y --no-install-recommends gcc-arm-linux-gnueabihf libc-dev-armhf-cross
+      shell: bash
+    - name: Cross-compile
+      run: cargo build --target armv7-unknown-linux-gnueabihf --features "${{ matrix.lua }} async send serialize vendored"
+      shell: bash
 
-  test_macos:
-    name: Test on MacOS
-    runs-on: macos-latest
+  test:
+    name: Test
+    runs-on: ${{ matrix.os }}
     needs: build
+    strategy:
+      matrix:
+        os: [ubuntu-18.04, macos-latest, windows-latest]
+        rust: [stable, nightly]
+        lua: [lua54, lua53, lua52, lua51, luajit]
+        include:
+        - os: ubuntu-18.04
+          target: x86_64-unknown-linux-gnu
+        - os: macos-latest
+          target: x86_64-apple-darwin
+        - os: windows-latest
+          target: x86_64-pc-windows-msvc
     steps:
-    - uses: actions/checkout@v1
-    - name: Install Rust
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: ${{ matrix.rust }}
+        target: ${{ matrix.target }}
+        override: true
+    - name: Run ${{ matrix.lua }} tests
       run: |
-        curl https://sh.rustup.rs | sh -s -- -y
-        echo ::add-path::$HOME/.cargo/bin
+        cargo test --release --features "${{ matrix.lua }} vendored"
+        cargo test --release --features "${{ matrix.lua }} vendored async send serialize"
       shell: bash
-    - name: Run tests (Lua 5.3 vendored)
-      run: cargo test --release --no-default-features --features "lua53 vendored"
-      shell: bash
-    - name: Run tests (Lua 5.2 vendored)
-      run: cargo test --release --no-default-features --features "lua52 vendored"
-      shell: bash
-    - name: Run tests (Lua 5.1 vendored)
-      run: cargo test --release --no-default-features --features "lua51 vendored"
-      shell: bash
-    - name: Run tests (LuaJIT vendored)
-      run: cargo test --release --no-default-features --features "luajit vendored"
+    - name: Run compile tests (macos lua53)
+      if: ${{ matrix.os == 'macos-latest' && matrix.lua == 'lua53' }}
+      run: |
+        TRYBUILD=overwrite cargo test --release --features "${{ matrix.lua }} vendored" -- --ignored
+        TRYBUILD=overwrite cargo test --release --features "${{ matrix.lua }} vendored async send serialize" -- --ignored
       shell: bash
 
-  test_windows:
-    name: Test on Windows
+  test_modules:
+    name: Test modules
+    runs-on: ${{ matrix.os }}
+    needs: build
+    strategy:
+      matrix:
+        os: [ubuntu-18.04, macos-latest]
+        rust: [stable, nightly]
+        lua: [lua54, lua53, lua52, lua51, luajit]
+        include:
+        - os: ubuntu-18.04
+          target: x86_64-unknown-linux-gnu
+        - os: macos-latest
+          target: x86_64-apple-darwin
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: ${{ matrix.rust }}
+        target: ${{ matrix.target }}
+        override: true
+    - name: Run ${{ matrix.lua }} module tests
+      run: |
+        (cd examples/module && cargo build --release --features "${{ matrix.lua }} vendored")
+        (cd tests/module && cargo test --release --features "${{ matrix.lua }} vendored")
+      shell: bash
+
+  test_modules_windows:
+    name: Test modules on Windows
     runs-on: windows-latest
     needs: build
+    strategy:
+      matrix:
+        lua: [lua54, luajit]
+    defaults:
+      run:
+        shell: msys2 {0}
     steps:
-    - uses: actions/checkout@v1
-    - name: Install Rust
-      run: rustup update stable --no-self-update && rustup default stable
-      shell: bash
-    - name: Run tests (Lua 5.3 vendored)
-      run: cargo test --release --no-default-features --features "lua53 vendored"
-      shell: bash
-    - name: Run tests (Lua 5.2 vendored)
-      run: cargo test --release --no-default-features --features "lua52 vendored"
-      shell: bash
-    - name: Run tests (Lua 5.1 vendored)
-      run: cargo test --release --no-default-features --features "lua51 vendored"
-      shell: bash
-    - name: Run tests (LuaJIT vendored)
-      run: cargo test --release --no-default-features --features "luajit vendored"
-      shell: bash
+    - uses: msys2/setup-msys2@v2
+    - uses: actions/checkout@v2
+    - name: Install Rust & Lua
+      run: |
+        pacman -S --noconfirm mingw-w64-x86_64-rust mingw-w64-x86_64-lua mingw-w64-x86_64-luajit mingw-w64-x86_64-pkg-config
+    - name: Run ${{ matrix.lua }} module tests
+      run: |
+        (cd examples/module && cargo build --release --features "${{ matrix.lua }}")
+        (cd tests/module && cargo test --release --features "${{ matrix.lua }}")
 
   rustfmt:
     name: Rustfmt
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v1
-    - name: Install Rust
-      run: rustup update stable && rustup default stable && rustup component add rustfmt
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        components: rustfmt
+        override: true
     - run: cargo fmt -- --check
+
+  clippy:
+    name: Clippy check
+    runs-on: ubuntu-18.04
+    strategy:
+      matrix:
+        lua: [lua54, lua53, lua52, lua51, luajit]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+            toolchain: nightly
+            components: clippy
+            override: true
+      - uses: actions-rs/clippy-check@v1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          args: --features "${{ matrix.lua }},vendored,async,send,serialize

CHANGELOG.md

@@ -0,0 +1,65 @@
+## v0.6.0-beta.1
+
+- New `UserDataFields` API
+- Allow to define arbitrary MetaMethods
+- `MetaMethods::name()` is public
+- Do not trigger longjmp in Rust to prevent unwinding across FFI boundaries. See https://github.com/rust-lang/rust/issues/83541
+- Added `SerializeOptions` to to change default Lua serializer behaviour (eg. nil/null/array serialization)
+- [**Breaking**] Removed `Result` from `LuaSerdeExt::null()` and `LuaSerdeExt::array_metatable()` (never fails)
+- [**Breaking**] Removed `Result` from `Function::dump()` (never fails)
+- `ToLua`/`FromLua` implementation for `Box<str>` and `Box<[T]>`
+- [**Breaking**] Added `LuaOptions` to customize Lua/Rust behaviour (currently panic handling)
+- Various bugfixes and performance improvements
+
+## v0.5.4
+
+- Build script improvements
+- Improvements in panic handling (resume panic on value popping)
+- Fixed bug serializing 3rd party userdata (causes segfault)
+- Make error::Error non exhaustive
+
+## v0.5.3
+
+- Fixed bug when returning nil-prefixed multi values from async function (+ test)
+- Performance optimisation for async callbacks (polling)
+
+## v0.5.2
+
+- Some performance optimisations (callbacks)
+- `ToLua` implementation for `Cow<str>` and `Cow<CStr>`
+- Fixed bug with `Scope` destruction of partially polled futures
+
+## v0.5.1
+
+- Support cross compilation that should work well for vendored builds (including LuaJIT with some restrictions)
+- Fix numeric types conversion for 32bit Lua
+- Update tokio to 1.0 for async examples
+
+## v0.5.0
+
+- Serde support under `serialize` feature flag.
+- Re-export `mlua_derive`.
+- impl `ToLua` and `FromLua` for `HashSet` and `BTreeSet`
+
+## v0.4.2
+
+- Added `Function::dump()` to dump lua function to a binary chunk
+- Added `ChunkMode` enum to mark chunks as text or binary
+- Updated `set_memory_limit` doc
+
+## v0.4.0
+
+- Lua 5.4 support with `MetaMethod::Close`.
+- `lua53` feature is disabled by default. Now preferred Lua version have to be chosen explicitly.
+- Provide safety guaraness for Lua state, which means that potenially unsafe operations, like loading C modules (using `require` or `package.loadlib`) are disabled. Equalient for the previous `Lua::new()` function is `Lua::unsafe_new()`.
+- New `send` feature to require `Send`.
+- New `module` feature, that disables linking to Lua Core Libraries. Required for modules.
+- Don't allow `'callback` outlive `'lua` in `Lua::create_function()` to fix [the unsoundness](tests/compile/static_callback_args.rs).
+- Added `Lua::into_static()` to make `'static` Lua state. This is useful to spawn async Lua threads that requires `'static`.
+- New function `Lua::set_memory_limit()` (similar to `rlua`) to enable memory restrictions in Lua VM (requires Lua >= 5.2).
+- `Scope`, temporary removed in v0.3, is back with async support.
+- Removed deprecated `Table::call()` function.
+- Added hooks support (backported from rlua 0.17).
+- New `AnyUserData::has_metamethod()` function.
+- LuaJIT 2.0.5 (the latest stable) support.
+- Various bug fixes and improvements.

Cargo.toml

@@ -1,52 +1,94 @@
 [package]
 name = "mlua"
-version = "0.2.2"
+version = "0.6.0-beta.1" # remember to update html_root_url and mlua_derive
 authors = ["Aleksandr Orlenko <zxteam@pm.me>", "kyren <catherine@chucklefish.org>"]
 edition = "2018"
 repository = "https://github.com/khvzak/mlua"
 documentation = "https://docs.rs/mlua"
 readme = "README.md"
-keywords = ["lua", "luajit"]
-categories = ["api-bindings"]
+keywords = ["lua", "luajit", "async", "futures", "scripting"]
+categories = ["api-bindings", "asynchronous"]
 license = "MIT"
 links = "lua"
 build = "build/main.rs"
 description = """
-High level bindings to Lua 5.1/5.2/5.3 (including LuaJIT)
-with support of writing native lua modules in Rust.
+High level bindings to Lua 5.4/5.3/5.2/5.1 (including LuaJIT)
+with async/await features and support of writing native lua modules in Rust.
 """
 
-[badges]
-# github-actions = { repository = "khvzak/mlua", workflow = "CI" }
+[package.metadata.docs.rs]
+features = ["lua53", "async", "send", "serialize"]
+rustdoc-args = ["--cfg", "docsrs"]
 
 [workspace]
 members = [
     "mlua_derive",
+    "examples/module",
+    "tests/module",
 ]
 
 [features]
-default = ["lua53"]
+lua54 = []
 lua53 = []
 lua52 = []
 lua51 = []
 luajit = []
 vendored = ["lua-src", "luajit-src"]
+module = ["mlua_derive"]
+async = ["futures-core", "futures-task", "futures-util"]
+send = []
+serialize = ["serde", "erased-serde"]
 
 [dependencies]
-num-traits = { version = "0.2.6" }
+mlua_derive = { version = "0.5", optional = true, path = "mlua_derive" }
 bstr = { version = "0.2", features = ["std"], default_features = false }
+once_cell = { version = "1.7" }
+num-traits = { version = "0.2.14" }
+futures-core = { version = "0.3.5", optional = true }
+futures-task = { version = "0.3.5", optional = true }
+futures-util = { version = "0.3.5", optional = true }
+serde = { version = "1.0", optional = true }
+erased-serde = { version = "0.3", optional = true }
 
 [build-dependencies]
 cc = { version = "1.0" }
-pkg-config = { version = "0.3.11" }
-lua-src = { version = "535.0.1", optional = true }
-luajit-src = { version = "210.0.0", optional = true }
+pkg-config = { version = "0.3.17" }
+lua-src = { version = ">= 540.0.0, < 550.0.0", optional = true }
+luajit-src = { version = ">= 210.1.2, < 220.0.0", optional = true }
 
 [dev-dependencies]
-rustyline = "5.0"
-criterion = "0.2.0"
+rustyline = "8.0"
+criterion = { version = "0.3.4", features = ["html_reports", "async_tokio"] }
 trybuild = "1.0"
+futures = "0.3.5"
+hyper = { version = "0.14", features = ["client", "server"] }
+reqwest = { version = "0.11", features = ["json"] }
+tokio = { version = "1.0", features = ["full"] }
+futures-timer = "3.0"
+serde_json = "1.0"
+maplit = "1.0"
 
 [[bench]]
 name = "benchmark"
 harness = false
+required-features = ["async"]
+
+[[example]]
+name = "async_http_client"
+required-features = ["async"]
+
+[[example]]
+name = "async_http_reqwest"
+required-features = ["async", "serialize"]
+
+[[example]]
+name = "async_http_server"
+required-features = ["async", "send"]
+
+[[example]]
+name = "async_tcp_server"
+required-features = ["async"]
+
+[[example]]
+name = "serialize"
+required-features = ["serialize"]

LICENSE

@@ -3,7 +3,7 @@ below:
 
 MIT License
 
-Copyright (c) 2019 A. Orlenko
+Copyright (c) 2019-2021 A. Orlenko
 Copyright (c) 2017 rlua
 
 Permission is hereby granted, free of charge, to any person obtaining a copy

README.md

@@ -1,5 +1,5 @@
 # mlua
-[![Build Status]][github-actions] [![Latest Version]][crates.io] [![API Documentation]][docs.rs]
+[![Build Status]][github-actions] [![Latest Version]][crates.io] [![API Documentation]][docs.rs] [![Coverage Status]][codecov.io]
 
 [Build Status]: https://github.com/khvzak/mlua/workflows/CI/badge.svg
 [github-actions]: https://github.com/khvzak/mlua/actions
@@ -7,22 +7,75 @@
 [crates.io]: https://crates.io/crates/mlua
 [API Documentation]: https://docs.rs/mlua/badge.svg
 [docs.rs]: https://docs.rs/mlua
+[Coverage Status]: https://codecov.io/gh/khvzak/mlua/branch/master/graph/badge.svg?token=99339FS1CG
+[codecov.io]: https://codecov.io/gh/khvzak/mlua
 
 [Guided Tour](examples/guided_tour.rs)
 
-A fork of [rlua 0.15](https://github.com/kyren/rlua/tree/0.15.3) which provides a high level
-interface between Rust and Lua. Unlike `rlua` , `mlua` supports Lua 5.1 (including LuaJIT), 5.2 and 5.3.
-The `mlua` goal is to be an easy to use, practical and flexible API between Rust and Lua but
-*__not__* always 100% safe due to the Lua VM nature. Also, `mlua` provides a way to write native lua
-modules in Rust.
+`mlua` is bindings to [Lua](https://www.lua.org) programming language for Rust with a goal to provide
+_safe_ (as far as it's possible), high level, easy to use, practical and flexible API.
+
+Started as [rlua](https://github.com/amethyst/rlua/tree/0.15.3) fork, `mlua` supports Lua 5.4, 5.3, 5.2 and 5.1 including LuaJIT (2.0.5 and 2.1 beta) and allows to write native Lua modules in Rust as well as use Lua in a standalone mode.
+
+`mlua` tested on Windows/macOS/Linux including module mode in [GitHub Actions] on `x86_64` platform and cross-compilation to `aarch64` (other targes are also supported).
+
+[GitHub Actions]: https://github.com/khvzak/mlua/actions
 
 ## Usage
 
-### Choosing Lua version
+### Feature flags
 
-The following features could be used to choose Lua version: `lua53` (default), `lua52`, `lua51` and `luajit`.
+`mlua` uses feature flags to reduce the amount of depenendies, compiled code and allow to choose only required set of features.
+Below is a list of the available feature flags. By default `mlua` does not enable any features.
 
-By default mlua uses `pkg-config` tool to find lua includes and lib.
+* `lua54`: activate Lua [5.4] support
+* `lua53`: activate Lua [5.3] support
+* `lua52`: activate Lua [5.2] support
+* `lua51`: activate Lua [5.1] support
+* `luajit`: activate [LuaJIT] support
+* `vendored`: build static Lua(JIT) library from sources during `mlua` compilation using [lua-src] or [luajit-src] crates
+* `module`: enable module mode (building loadable `cdylib` library for Lua)
+* `async`: enable async/await support (any executor can be used, eg. [tokio] or [async-std])
+* `send`: make `mlua::Lua` transferable across thread boundaries (adds [`Send`] requirement to `mlua::Function` and `mlua::UserData`)
+* `serialize`: add serialization and deserialization support to `mlua` types using [serde] framework
+
+[5.4]: https://www.lua.org/manual/5.4/manual.html
+[5.3]: https://www.lua.org/manual/5.3/manual.html
+[5.2]: https://www.lua.org/manual/5.2/manual.html
+[5.1]: https://www.lua.org/manual/5.1/manual.html
+[LuaJIT]: https://luajit.org/
+[lua-src]: https://github.com/khvzak/lua-src-rs
+[luajit-src]: https://github.com/khvzak/luajit-src-rs
+[tokio]: https://github.com/tokio-rs/tokio
+[async-std]: https://github.com/async-rs/async-std
+[`Send`]: https://doc.rust-lang.org/std/marker/trait.Send.html
+[serde]: https://github.com/serde-rs/serde
+
+### Async/await support
+
+`mlua` supports async/await for all Lua versions. This works using Lua [coroutines](https://www.lua.org/manual/5.3/manual.html#2.6) and require running [Thread](https://docs.rs/mlua/latest/mlua/struct.Thread.html) along with enabling `feature = "async"` in `Cargo.toml`.
+
+**Examples**:
+- [HTTP Client](examples/async_http_client.rs)
+- [HTTP Client (json)](examples/async_http_reqwest.rs)
+- [HTTP Server](examples/async_http_server.rs)
+- [TCP Server](examples/async_tcp_server.rs)
+
+### Serialization (serde) support
+
+With `serialize` feature flag enabled, `mlua` allows you to serialize/deserialize any type that implements [`serde::Serialize`] and [`serde::Deserialize`] into/from [`mlua::Value`]. In addition `mlua` provides [`serde::Serialize`] trait implementation for it (including `UserData` support).
+
+[Example](examples/serialize.rs)
+
+[`serde::Serialize`]: https://docs.serde.rs/serde/ser/trait.Serialize.html
+[`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
+[`mlua::Value`]: https://docs.rs/mlua/latest/mlua/enum.Value.html
+
+### Compiling
+
+You have to enable one of the features `lua54`, `lua53`, `lua52`, `lua51` or `luajit`, according to the choosen Lua version.
+
+By default `mlua` uses `pkg-config` tool to find lua includes and libraries for the chosen Lua version.
 In most cases it works as desired, although sometimes could be more preferable to use a custom lua library.
 To achieve this, mlua supports `LUA_INC`, `LUA_LIB`, `LUA_LIB_NAME` and `LUA_LINK` environment variables.
 `LUA_LINK` is optional and may be `dylib` (a dynamic library) or `static` (a static library, `.a` archive).
@@ -34,14 +87,16 @@ my_project $ LUA_INC=$HOME/tmp/lua-5.2.4/src LUA_LIB=$HOME/tmp/lua-5.2.4/src LUA
 
 `mlua` also supports vendored lua/luajit using the auxilary crates [lua-src](https://crates.io/crates/lua-src) and
 [luajit-src](https://crates.io/crates/luajit-src).
-Just enable the `vendored` feature and cargo will automatically build and link specified lua/luajit version. This is the easiest way to get started with mlua.
+Just enable the `vendored` feature and cargo will automatically build and link specified lua/luajit version. This is the easiest way to get started with `mlua`.
 
 ### Standalone mode
+In a standalone mode `mlua` allows to add to your application scripting support with a gently configured Lua runtime to ensure  safety and soundness.
+
 Add to `Cargo.toml` :
 
 ``` toml
 [dependencies]
-mlua = "0.2"
+mlua = { version = "0.5", features = ["lua53", "vendored"] }
 ```
 
 `main.rs`
@@ -65,6 +120,9 @@ fn main() -> LuaResult<()> {
 ```
 
 ### Module mode
+In a module mode `mlua` allows to create a compiled Lua module that can be loaded from Lua code using [`require`](https://www.lua.org/manual/5.3/manual.html#pdf-require). In this case `mlua` uses an external Lua runtime which could lead to potential unsafety due to unpredictability of the Lua environment and usage of libraries such as [`debug`](https://www.lua.org/manual/5.3/manual.html#6.10).
+
+[Example](examples/module)
 
 Add to `Cargo.toml` :
 
@@ -73,15 +131,12 @@ Add to `Cargo.toml` :
 crate-type = ["cdylib"]
 
 [dependencies]
-mlua = "0.2"
-mlua_derive = "0.2"
+mlua = { version = "0.5", features = ["lua53", "vendored", "module"] }
 ```
 
 `lib.rs` :
 
 ``` rust
-#[macro_use]
-extern crate mlua_derive;
 use mlua::prelude::*;
 
 fn hello(_: &Lua, name: String) -> LuaResult<()> {
@@ -89,7 +144,7 @@ fn hello(_: &Lua, name: String) -> LuaResult<()> {
     Ok(())
 }
 
-#[lua_module]
+#[mlua::lua_module]
 fn my_module(lua: &Lua) -> LuaResult<LuaTable> {
     let exports = lua.create_table()?;
     exports.set("hello", lua.create_function(hello)?)?;
@@ -97,32 +152,53 @@ fn my_module(lua: &Lua) -> LuaResult<LuaTable> {
 }
 ```
 
-And then (macos example):
+And then (**macOS** example):
 
 ``` sh
-$ cargo build
+$ cargo rustc -- -C link-arg=-undefined -C link-arg=dynamic_lookup
 $ ln -s ./target/debug/libmy_module.dylib ./my_module.so
 $ lua5.3 -e 'require("my_module").hello("world")'
 hello, world!
 ```
 
+On macOS, you need to set additional linker arguments. One option is to compile with `cargo rustc --release -- -C link-arg=-undefined -C link-arg=dynamic_lookup`, the other is to create a `.cargo/config` with the following content:
+``` toml
+[target.x86_64-apple-darwin]
+rustflags = [
+  "-C", "link-arg=-undefined",
+  "-C", "link-arg=dynamic_lookup",
+]
+
+[target.aarch64-apple-darwin]
+rustflags = [
+  "-C", "link-arg=-undefined",
+  "-C", "link-arg=dynamic_lookup",
+]
+```
+On Linux you can build modules normally with `cargo build --release`.
+Vendored and non-vendored builds are supported for these OS.
+
+On Windows `vendored` mode for modules is not supported since you need to link to a Lua dll.
+Easiest way is to use either MinGW64 (as part of [MSYS2](https://github.com/msys2/msys2) package) with `pkg-config` or
+MSVC with `LUA_INC` / `LUA_LIB` / `LUA_LIB_NAME` environment variables.
+
+More details about compiling and linking Lua modules can be found on the [Building Modules](http://lua-users.org/wiki/BuildingModules) page.
+
 ## Safety
 
 One of the `mlua` goals is to provide *safe* API between Rust and Lua.
-Every place where the Lua C API may trigger an error longjmp
-in any way is protected by `lua_pcall` , and the user of the library is protected
-from directly interacting with unsafe things like the Lua stack, and there is
-overhead associated with this safety.
+Every place where the Lua C API may trigger an error longjmp in any way is protected by `lua_pcall`,
+and the user of the library is protected from directly interacting with unsafe things like the Lua stack,
+and there is overhead associated with this safety.
 
 Unfortunately, `mlua` does not provide absolute safety even without using `unsafe` .
-This library contains a huge amount of unsafe code. There are almost
-certainly bugs still lurking in this library!  It is surprisingly, fiendishly
-difficult to use the Lua C API without the potential for unsafety.
+This library contains a huge amount of unsafe code. There are almost certainly bugs still lurking in this library!
+It is surprisingly, fiendishly difficult to use the Lua C API without the potential for unsafety.
 
 ## Panic handling
 
 `mlua` wraps panics that are generated inside Rust callbacks in a regular Lua error. Panics could be
-resumed then by propagating the Lua error to Rust code.
+resumed then by returning or propagating the Lua error to Rust code.
 
 For example:
 ``` rust
@@ -141,18 +217,21 @@ let _ = lua.load(r#"
 unreachable!()
 ```
 
-`mlua` should also be panic safe in another way as well, which is that any `Lua`
-instances or handles remains usable after a user generated panic, and such
-panics should not break internal invariants or leak Lua stack space. This is
-mostly important to safely use `mlua` types in Drop impls, as you should not be
+Optionally `mlua` can disable Rust panics catching in Lua via `pcall`/`xpcall` and automatically resume
+them across the Lua API boundary. This is controlled via `LuaOptions` and done by wrapping the Lua `pcall`/`xpcall`
+functions on a way to prevent catching errors that are wrapped Rust panics.
+
+`mlua` should also be panic safe in another way as well, which is that any `Lua` instances or handles
+remains usable after a user generated panic, and such panics should not break internal invariants or
+leak Lua stack space. This is mostly important to safely use `mlua` types in Drop impls, as you should not be
 using panics for general error handling.
 
 Below is a list of `mlua` behaviors that should be considered a bug.
 If you encounter them, a bug report would be very welcome:
 
-  + If your program panics with a message that contains the string "mlua internal error", this is a  bug.
+  + If you can cause UB with `mlua` without typing the word "unsafe", this is a bug.
 
-  + The above is true even for the internal panic about running out of stack space!  There are a few ways to generate normal script errors by running out of stack, but if you encounter a *panic* based on running out of stack, this is a bug.
+  + If your program panics with a message that contains the string "mlua internal error", this is a bug.
 
   + Lua C API errors are handled by lonjmp. All instances where the Lua C API would otherwise longjmp over calling stack frames should be guarded against, except in internal callbacks where this is intentional. If you detect that `mlua` is triggering a longjmp over your Rust stack frames, this is a bug!
 
@@ -161,4 +240,3 @@ If you encounter them, a bug report would be very welcome:
 ## License
 
 This project is licensed under the [MIT license](LICENSE)
-

benches/benchmark.rs

@@ -1,22 +1,22 @@
-#![cfg_attr(
-    all(feature = "luajit", target_os = "macos", target_arch = "x86_64"),
-    feature(link_args)
-)]
-
-#[cfg_attr(
-    all(feature = "luajit", target_os = "macos", target_arch = "x86_64"),
-    link_args = "-pagezero_size 10000 -image_base 100000000"
-)]
-extern "system" {}
-
 use criterion::{criterion_group, criterion_main, BatchSize, Criterion};
+use std::time::Duration;
+use tokio::runtime::Runtime;
+use tokio::task;
+
 use mlua::prelude::*;
 
+fn collect_gc_twice(lua: &Lua) {
+    lua.gc_collect().unwrap();
+    lua.gc_collect().unwrap();
+}
+
 fn create_table(c: &mut Criterion) {
-    c.bench_function("create table", |b| {
-        b.iter_batched_ref(
-            || Lua::new(),
-            |lua| {
+    let lua = Lua::new();
+
+    c.bench_function("create [table empty]", |b| {
+        b.iter_batched(
+            || collect_gc_twice(&lua),
+            |_| {
                 lua.create_table().unwrap();
             },
             BatchSize::SmallInput,
@@ -25,12 +25,14 @@ fn create_table(c: &mut Criterion) {
 }
 
 fn create_array(c: &mut Criterion) {
-    c.bench_function("create array 10", |b| {
-        b.iter_batched_ref(
-            || Lua::new(),
-            |lua| {
+    let lua = Lua::new();
+
+    c.bench_function("create [array] 10", |b| {
+        b.iter_batched(
+            || collect_gc_twice(&lua),
+            |_| {
                 let table = lua.create_table().unwrap();
-                for i in 1..11 {
+                for i in 1..=10 {
                     table.set(i, i).unwrap();
                 }
             },
@@ -40,10 +42,12 @@ fn create_array(c: &mut Criterion) {
 }
 
 fn create_string_table(c: &mut Criterion) {
-    c.bench_function("create string table 10", |b| {
-        b.iter_batched_ref(
-            || Lua::new(),
-            |lua| {
+    let lua = Lua::new();
+
+    c.bench_function("create [table string] 10", |b| {
+        b.iter_batched(
+            || collect_gc_twice(&lua),
+            |_| {
                 let table = lua.create_table().unwrap();
                 for &s in &["1", "2", "3", "4", "5", "6", "7", "8", "9", "10"] {
                     let s = lua.create_string(s).unwrap();
@@ -55,30 +59,20 @@ fn create_string_table(c: &mut Criterion) {
     });
 }
 
-fn call_add_function(c: &mut Criterion) {
-    c.bench_function("call add function 3 10", |b| {
+fn call_lua_function(c: &mut Criterion) {
+    let lua = Lua::new();
+
+    c.bench_function("call Lua function [sum] 3 10", |b| {
         b.iter_batched_ref(
             || {
-                let lua = Lua::new();
-                let f = {
-                    let f: LuaFunction = lua
-                        .load(
-                            r#"
-                                function(a, b, c)
-                                    return a + b + c
-                                end
-                            "#,
-                        )
-                        .eval()
-                        .unwrap();
-                    lua.create_registry_value(f).unwrap()
-                };
-                (lua, f)
+                collect_gc_twice(&lua);
+                lua.load("function(a, b, c) return a + b + c end")
+                    .eval::<LuaFunction>()
+                    .unwrap()
             },
-            |(lua, f)| {
-                let add_function: LuaFunction = lua.registry_value(f).unwrap();
+            |function| {
                 for i in 0..10 {
-                    let _result: i64 = add_function.call((i, i + 1, i + 2)).unwrap();
+                    let _result: i64 = function.call((i, i + 1, i + 2)).unwrap();
                 }
             },
             BatchSize::SmallInput,
@@ -86,72 +80,75 @@ fn call_add_function(c: &mut Criterion) {
     });
 }
 
-fn call_add_callback(c: &mut Criterion) {
-    c.bench_function("call callback add 2 10", |b| {
+fn call_sum_callback(c: &mut Criterion) {
+    let lua = Lua::new();
+    let callback = lua
+        .create_function(|_, (a, b, c): (i64, i64, i64)| Ok(a + b + c))
+        .unwrap();
+    lua.globals().set("callback", callback).unwrap();
+
+    c.bench_function("call Rust callback [sum] 3 10", |b| {
         b.iter_batched_ref(
             || {
-                let lua = Lua::new();
-                let f = {
-                    let c: LuaFunction = lua
-                        .create_function(|_, (a, b, c): (i64, i64, i64)| Ok(a + b + c))
-                        .unwrap();
-                    lua.globals().set("callback", c).unwrap();
-                    let f: LuaFunction = lua
-                        .load(
-                            r#"
-                            function()
-                                for i = 1,10 do
-                                    callback(i, i, i)
-                                end
-                            end
-                        "#,
-                        )
-                        .eval()
-                        .unwrap();
-                    lua.create_registry_value(f).unwrap()
-                };
-                (lua, f)
+                collect_gc_twice(&lua);
+                lua.load("function() for i = 1,10 do callback(i, i+1, i+2) end end")
+                    .eval::<LuaFunction>()
+                    .unwrap()
             },
-            |(lua, f)| {
-                let entry_function: LuaFunction = lua.registry_value(f).unwrap();
-                entry_function.call::<_, ()>(()).unwrap();
+            |function| {
+                function.call::<_, ()>(()).unwrap();
             },
             BatchSize::SmallInput,
         );
     });
 }
 
-fn call_append_callback(c: &mut Criterion) {
-    c.bench_function("call callback append 10", |b| {
+fn call_async_sum_callback(c: &mut Criterion) {
+    let lua = Lua::new();
+    let callback = lua
+        .create_async_function(|_, (a, b, c): (i64, i64, i64)| async move {
+            task::yield_now().await;
+            Ok(a + b + c)
+        })
+        .unwrap();
+    lua.globals().set("callback", callback).unwrap();
+
+    c.bench_function("call async Rust callback [sum] 3 10", |b| {
+        let rt = Runtime::new().unwrap();
+        b.to_async(rt).iter_batched(
+            || {
+                collect_gc_twice(&lua);
+                lua.load("function() for i = 1,10 do callback(i, i+1, i+2) end end")
+                    .eval::<LuaFunction>()
+                    .unwrap()
+            },
+            |function| async move {
+                function.call_async::<_, ()>(()).await.unwrap();
+            },
+            BatchSize::SmallInput,
+        );
+    });
+}
+
+fn call_concat_callback(c: &mut Criterion) {
+    let lua = Lua::new();
+    let callback = lua
+        .create_function(|_, (a, b): (LuaString, LuaString)| {
+            Ok(format!("{}{}", a.to_str()?, b.to_str()?))
+        })
+        .unwrap();
+    lua.globals().set("callback", callback).unwrap();
+
+    c.bench_function("call Rust callback [concat string] 10", |b| {
         b.iter_batched_ref(
             || {
-                let lua = Lua::new();
-                let f = {
-                    let c: LuaFunction = lua
-                        .create_function(|_, (a, b): (LuaString, LuaString)| {
-                            Ok(format!("{}{}", a.to_str()?, b.to_str()?))
-                        })
-                        .unwrap();
-                    lua.globals().set("callback", c).unwrap();
-                    let f: LuaFunction = lua
-                        .load(
-                            r#"
-                            function()
-                                for _ = 1,10 do
-                                    callback("a", "b")
-                                end
-                            end
-                        "#,
-                        )
-                        .eval()
-                        .unwrap();
-                    lua.create_registry_value(f).unwrap()
-                };
-                (lua, f)
+                collect_gc_twice(&lua);
+                lua.load("function() for i = 1,10 do callback('a', tostring(i)) end end")
+                    .eval::<LuaFunction>()
+                    .unwrap()
             },
-            |(lua, f)| {
-                let entry_function: LuaFunction = lua.registry_value(f).unwrap();
-                entry_function.call::<_, ()>(()).unwrap();
+            |function| {
+                function.call::<_, ()>(()).unwrap();
             },
             BatchSize::SmallInput,
         );
@@ -159,10 +156,12 @@ fn call_append_callback(c: &mut Criterion) {
 }
 
 fn create_registry_values(c: &mut Criterion) {
-    c.bench_function("create registry 10", |b| {
-        b.iter_batched_ref(
-            || Lua::new(),
-            |lua| {
+    let lua = Lua::new();
+
+    c.bench_function("create [registry value] 10", |b| {
+        b.iter_batched(
+            || collect_gc_twice(&lua),
+            |_| {
                 for _ in 0..10 {
                     lua.create_registry_value(lua.pack(true).unwrap()).unwrap();
                 }
@@ -177,10 +176,12 @@ fn create_userdata(c: &mut Criterion) {
     struct UserData(i64);
     impl LuaUserData for UserData {}
 
-    c.bench_function("create userdata 10", |b| {
-        b.iter_batched_ref(
-            || Lua::new(),
-            |lua| {
+    let lua = Lua::new();
+
+    c.bench_function("create [table userdata] 10", |b| {
+        b.iter_batched(
+            || collect_gc_twice(&lua),
+            |_| {
                 let table: LuaTable = lua.create_table().unwrap();
                 for i in 1..11 {
                     table.set(i, UserData(i)).unwrap();
@@ -191,20 +192,80 @@ fn create_userdata(c: &mut Criterion) {
     });
 }
 
+fn call_userdata_method(c: &mut Criterion) {
+    struct UserData(i64);
+    impl LuaUserData for UserData {
+        fn add_methods<'lua, M: LuaUserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_method("method", |_, this, ()| Ok(this.0));
+        }
+    }
+
+    let lua = Lua::new();
+    lua.globals().set("userdata", UserData(10)).unwrap();
+
+    c.bench_function("call [userdata method] 10", |b| {
+        b.iter_batched_ref(
+            || {
+                collect_gc_twice(&lua);
+                lua.load("function() for i = 1,10 do userdata:method() end end")
+                    .eval::<LuaFunction>()
+                    .unwrap()
+            },
+            |function| {
+                function.call::<_, ()>(()).unwrap();
+            },
+            BatchSize::SmallInput,
+        );
+    });
+}
+
+fn call_async_userdata_method(c: &mut Criterion) {
+    #[derive(Clone, Copy)]
+    struct UserData(i64);
+    impl LuaUserData for UserData {
+        fn add_methods<'lua, M: LuaUserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_async_method("method", |_, this, ()| async move { Ok(this.0) });
+        }
+    }
+
+    let lua = Lua::new();
+    lua.globals().set("userdata", UserData(10)).unwrap();
+
+    c.bench_function("call async [userdata method] 10", |b| {
+        let rt = Runtime::new().unwrap();
+        b.to_async(rt).iter_batched(
+            || {
+                collect_gc_twice(&lua);
+                lua.load("function() for i = 1,10 do userdata:method() end end")
+                    .eval::<LuaFunction>()
+                    .unwrap()
+            },
+            |function| async move {
+                function.call_async::<_, ()>(()).await.unwrap();
+            },
+            BatchSize::SmallInput,
+        );
+    });
+}
+
 criterion_group! {
     name = benches;
     config = Criterion::default()
-        .sample_size(200)
+        .sample_size(300)
+        .measurement_time(Duration::from_secs(10))
         .noise_threshold(0.02);
     targets =
         create_table,
         create_array,
         create_string_table,
-        call_add_function,
-        call_add_callback,
-        call_append_callback,
+        call_lua_function,
+        call_sum_callback,
+        call_async_sum_callback,
+        call_concat_callback,
         create_registry_values,
         create_userdata,
+        call_userdata_method,
+        call_async_userdata_method,
 }
 
 criterion_main!(benches);

build/find_dummy.rs

@@ -0,0 +1,5 @@
+use std::path::PathBuf;
+
+pub fn probe_lua() -> PathBuf {
+    unreachable!()
+}

build/find_normal.rs

@@ -1,106 +1,119 @@
 use std::env;
-use std::ffi::OsString;
-use std::fs::File;
-use std::io::{BufRead, BufReader, Result};
 use std::ops::Bound;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
+
+fn get_env_var(name: &str) -> String {
+    match env::var(name) {
+        Ok(val) => val,
+        Err(env::VarError::NotPresent) => String::new(),
+        Err(err) => panic!("cannot get {}: {}", name, err),
+    }
+}
 
 pub fn probe_lua() -> PathBuf {
-    let include_dir = env::var_os("LUA_INC").unwrap_or(OsString::new());
-    let lib_dir = env::var_os("LUA_LIB").unwrap_or(OsString::new());
-    let lua_lib = env::var_os("LUA_LIB_NAME").unwrap_or(OsString::new());
+    let include_dir = get_env_var("LUA_INC");
+    let lib_dir = get_env_var("LUA_LIB");
+    let lua_lib = get_env_var("LUA_LIB_NAME");
 
     println!("cargo:rerun-if-env-changed=LUA_INC");
     println!("cargo:rerun-if-env-changed=LUA_LIB");
     println!("cargo:rerun-if-env-changed=LUA_LIB_NAME");
     println!("cargo:rerun-if-env-changed=LUA_LINK");
 
-    if include_dir != "" && lib_dir != "" && lua_lib != "" {
-        let _version = use_custom_lua(&include_dir, &lib_dir, &lua_lib).unwrap();
+    let need_lua_lib = cfg!(any(not(feature = "module"), target_os = "windows"));
+
+    if include_dir != "" {
+        if need_lua_lib {
+            if lib_dir == "" {
+                panic!("LUA_LIB is not set");
+            }
+            if lua_lib == "" {
+                panic!("LUA_LIB_NAME is not set");
+            }
+
+            let mut link_lib = "";
+            if get_env_var("LUA_LINK") == "static" {
+                link_lib = "static=";
+            };
+            println!("cargo:rustc-link-search=native={}", lib_dir);
+            println!("cargo:rustc-link-lib={}{}", link_lib, lua_lib);
+        }
         return PathBuf::from(include_dir);
     }
 
-    // Find using via pkg-config
+    // Find using `pkg-config`
+
+    #[cfg(feature = "lua54")]
+    {
+        let mut lua = pkg_config::Config::new()
+            .range_version((Bound::Included("5.4"), Bound::Excluded("5.5")))
+            .cargo_metadata(need_lua_lib)
+            .probe("lua");
+
+        if lua.is_err() {
+            lua = pkg_config::Config::new()
+                .cargo_metadata(need_lua_lib)
+                .probe("lua5.4");
+        }
+
+        lua.unwrap().include_paths[0].clone()
+    }
 
     #[cfg(feature = "lua53")]
     {
         let mut lua = pkg_config::Config::new()
             .range_version((Bound::Included("5.3"), Bound::Excluded("5.4")))
+            .cargo_metadata(need_lua_lib)
             .probe("lua");
 
         if lua.is_err() {
-            lua = pkg_config::Config::new().probe("lua5.3");
+            lua = pkg_config::Config::new()
+                .cargo_metadata(need_lua_lib)
+                .probe("lua5.3");
         }
 
-        return lua.unwrap().include_paths[0].clone();
+        lua.unwrap().include_paths[0].clone()
     }
 
     #[cfg(feature = "lua52")]
     {
         let mut lua = pkg_config::Config::new()
             .range_version((Bound::Included("5.2"), Bound::Excluded("5.3")))
+            .cargo_metadata(need_lua_lib)
             .probe("lua");
 
         if lua.is_err() {
-            lua = pkg_config::Config::new().probe("lua5.2");
+            lua = pkg_config::Config::new()
+                .cargo_metadata(need_lua_lib)
+                .probe("lua5.2");
         }
 
-        return lua.unwrap().include_paths[0].clone();
+        lua.unwrap().include_paths[0].clone()
     }
 
     #[cfg(feature = "lua51")]
     {
         let mut lua = pkg_config::Config::new()
             .range_version((Bound::Included("5.1"), Bound::Excluded("5.2")))
+            .cargo_metadata(need_lua_lib)
             .probe("lua");
 
         if lua.is_err() {
-            lua = pkg_config::Config::new().probe("lua5.1");
+            lua = pkg_config::Config::new()
+                .cargo_metadata(need_lua_lib)
+                .probe("lua5.1");
         }
 
-        return lua.unwrap().include_paths[0].clone();
+        lua.unwrap().include_paths[0].clone()
     }
 
     #[cfg(feature = "luajit")]
     {
         let lua = pkg_config::Config::new()
-            .range_version((Bound::Included("2.1.0"), Bound::Unbounded))
+            .range_version((Bound::Included("2.0.5"), Bound::Unbounded))
+            .cargo_metadata(need_lua_lib)
             .probe("luajit");
 
-        return lua.unwrap().include_paths[0].clone();
+        lua.unwrap().include_paths[0].clone()
     }
 }
-
-fn use_custom_lua<S: AsRef<Path>>(include_dir: &S, lib_dir: &S, lua_lib: &S) -> Result<String> {
-    let mut version_found = String::new();
-
-    // Find LUA_VERSION_NUM
-    let mut lua_h_path = include_dir.as_ref().to_owned();
-    lua_h_path.push("lua.h");
-    let f = File::open(lua_h_path)?;
-    let reader = BufReader::new(f);
-    for line in reader.lines() {
-        let line = line?;
-        let parts = line.split_whitespace().collect::<Vec<_>>();
-        if parts.len() == 3 && parts[1] == "LUA_VERSION_NUM" {
-            version_found = parts[2].to_string();
-        }
-    }
-
-    let mut link_lib = String::new();
-    if env::var("LUA_LINK").unwrap_or(String::new()) == "static" {
-        link_lib = "static=".to_string();
-    }
-
-    println!(
-        "cargo:rustc-link-search=native={}",
-        lib_dir.as_ref().display()
-    );
-    println!(
-        "cargo:rustc-link-lib={}{}",
-        link_lib,
-        lua_lib.as_ref().display()
-    );
-
-    Ok(version_found)
-}

build/find_vendored.rs

@@ -1,11 +1,8 @@
 use std::path::PathBuf;
 
-#[cfg(any(feature = "lua53", feature = "lua52", feature = "lua51"))]
-use lua_src;
-#[cfg(feature = "luajit")]
-use luajit_src;
-
 pub fn probe_lua() -> PathBuf {
+    #[cfg(feature = "lua54")]
+    let artifacts = lua_src::Build::new().build(lua_src::Lua54);
     #[cfg(feature = "lua53")]
     let artifacts = lua_src::Build::new().build(lua_src::Lua53);
     #[cfg(feature = "lua52")]
@@ -15,6 +12,8 @@ pub fn probe_lua() -> PathBuf {
     #[cfg(feature = "luajit")]
     let artifacts = luajit_src::Build::new().build();
 
+    #[cfg(not(feature = "module"))]
     artifacts.print_cargo_metadata();
+
     artifacts.include_dir().to_owned()
 }

build/main.rs

@@ -1,12 +1,47 @@
 #![allow(unreachable_code)]
 
 use std::env;
-use std::io::{Error, ErrorKind, Result};
+use std::fs::File;
+use std::io::{Error, ErrorKind, Result, Write};
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-#[cfg_attr(feature = "vendored", path = "find_vendored.rs")]
-#[cfg_attr(not(feature = "vendored"), path = "find_normal.rs")]
+#[cfg_attr(
+    all(
+        feature = "vendored",
+        any(
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "lua51",
+            feature = "luajit"
+        )
+    ),
+    path = "find_vendored.rs"
+)]
+#[cfg_attr(
+    all(
+        not(feature = "vendored"),
+        any(
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "lua51",
+            feature = "luajit"
+        )
+    ),
+    path = "find_normal.rs"
+)]
+#[cfg_attr(
+    not(any(
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "lua51",
+        feature = "luajit"
+    )),
+    path = "find_dummy.rs"
+)]
 mod find;
 
 trait CommandExt {
@@ -57,30 +92,161 @@ fn build_glue<P: AsRef<Path> + std::fmt::Debug>(include_path: &P) {
         .unwrap();
 }
 
+// When cross-compiling, we cannot use `build_glue` as we cannot run the generated
+// executable.  Instead, let's take a stab at synthesizing the likely values.
+// If you're cross-compiling and using a non-vendored library then there is a chance
+// that the values selected here may be incorrect, but we have no way to determine
+// that here.
+fn generate_glue() -> Result<()> {
+    let build_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    let mut glue = File::create(build_dir.join("glue.rs"))?;
+    writeln!(
+        glue,
+        "/* This file was generated by build/main.rs; do not modify by hand */"
+    )?;
+    writeln!(glue, "use std::os::raw::*;")?;
+
+    writeln!(glue, "/* luaconf.h */")?;
+    let pointer_bit_width: usize = env::var("CARGO_CFG_TARGET_POINTER_WIDTH")
+        .unwrap()
+        .parse()
+        .unwrap();
+    writeln!(
+        glue,
+        "pub const LUA_EXTRASPACE: c_int = {} / 8;",
+        pointer_bit_width
+    )?;
+
+    // This is generally hardcoded to this size
+    writeln!(glue, "pub const LUA_IDSIZE: c_int = 60;")?;
+
+    // Unless the target is restricted, the defaults are 64 bit
+    writeln!(glue, "pub type LUA_NUMBER = c_double;")?;
+    writeln!(glue, "pub type LUA_INTEGER = i64;")?;
+    writeln!(glue, "pub type LUA_UNSIGNED = u64;")?;
+
+    writeln!(glue, "/* lua.h */")?;
+    let version = if cfg!(any(feature = "luajit", feature = "lua51")) {
+        (5, 1, 0)
+    } else if cfg!(feature = "lua52") {
+        (5, 2, 0)
+    } else if cfg!(feature = "lua53") {
+        (5, 3, 0)
+    } else if cfg!(feature = "lua54") {
+        (5, 4, 0)
+    } else {
+        unreachable!();
+    };
+    writeln!(
+        glue,
+        "pub const LUA_VERSION_NUM: c_int = {};",
+        (version.0 * 100) + version.1
+    )?;
+
+    let max_stack = if pointer_bit_width >= 32 {
+        1_000_000
+    } else {
+        15_000
+    };
+    writeln!(
+        glue,
+        "pub const LUA_REGISTRYINDEX: c_int = -{} - 1000;",
+        max_stack
+    )?;
+
+    // These two are only defined in lua 5.1
+    writeln!(glue, "pub const LUA_ENVIRONINDEX: c_int = -10001;")?;
+    writeln!(glue, "pub const LUA_GLOBALSINDEX: c_int = -10002;")?;
+
+    writeln!(glue, "/* lauxlib.h */")?;
+    // This is only defined in lua 5.3 and up, but we can always generate its value here,
+    // even if we don't use it.
+    // This matches the default definition in lauxlib.h
+    writeln!(glue, "pub const LUAL_NUMSIZES: c_int = std::mem::size_of::<LUA_INTEGER>() as c_int * 16 + std::mem::size_of::<LUA_NUMBER>() as c_int;")?;
+
+    writeln!(glue, "/* lualib.h */")?;
+    write!(
+        glue,
+        r#"
+#[cfg(feature = "luajit")]
+pub const LUA_BITLIBNAME: &str = "bit";
+#[cfg(not(feature = "luajit"))]
+pub const LUA_BITLIBNAME: &str = "bit32";
+
+pub const LUA_COLIBNAME: &str = "coroutine";
+pub const LUA_DBLIBNAME: &str = "debug";
+pub const LUA_IOLIBNAME: &str = "io";
+pub const LUA_LOADLIBNAME: &str = "package";
+pub const LUA_MATHLIBNAME: &str = "math";
+pub const LUA_OSLIBNAME: &str = "os";
+pub const LUA_STRLIBNAME: &str = "string";
+pub const LUA_TABLIBNAME: &str = "table";
+pub const LUA_UTF8LIBNAME: &str = "utf8";
+
+pub const LUA_JITLIBNAME: &str = "jit";
+pub const LUA_FFILIBNAME: &str = "ffi";
+"#
+    )?;
+
+    Ok(())
+}
+
 fn main() {
     #[cfg(not(any(
+        feature = "lua54",
         feature = "lua53",
         feature = "lua52",
         feature = "lua51",
         feature = "luajit"
     )))]
-    panic!("You must enable one of the features: lua53, lua52, lua51, luajit");
+    compile_error!("You must enable one of the features: lua54, lua53, lua52, lua51, luajit");
+
+    #[cfg(all(
+        feature = "lua54",
+        any(
+            feature = "lua53",
+            feature = "lua52",
+            feature = "lua51",
+            feature = "luajit"
+        )
+    ))]
+    compile_error!("You can enable only one of the features: lua54, lua53, lua52, lua51, luajit");
 
     #[cfg(all(
         feature = "lua53",
         any(feature = "lua52", feature = "lua51", feature = "luajit")
     ))]
-    panic!("You can enable only one of the features: lua53, lua52, lua51, luajit");
+    compile_error!("You can enable only one of the features: lua54, lua53, lua52, lua51, luajit");
 
     #[cfg(all(feature = "lua52", any(feature = "lua51", feature = "luajit")))]
-    panic!("You can enable only one of the features: lua53, lua52, lua51, luajit");
+    compile_error!("You can enable only one of the features: lua54, lua53, lua52, lua51, luajit");
 
     #[cfg(all(feature = "lua51", feature = "luajit"))]
-    panic!("You can enable only one of the features: lua53, lua52, lua51, luajit");
+    compile_error!("You can enable only one of the features: lua54, lua53, lua52, lua51, luajit");
 
-    #[cfg(all(feature = "lua51", feature = "luajit"))]
-    panic!("You can enable only one of the features: lua53, lua52, lua51, luajit");
+    // We don't support "vendored module" mode on windows
+    #[cfg(all(feature = "vendored", feature = "module", target_os = "windows"))]
+    compile_error!(
+        "Vendored (static) builds are not supported for modules on Windows.\n"
+            + "Please, use `pkg-config` or custom mode to link to a Lua dll."
+    );
 
     let include_dir = find::probe_lua();
-    build_glue(&include_dir);
+    if env::var("TARGET").unwrap() != env::var("HOST").unwrap() {
+        generate_glue().unwrap();
+    } else {
+        build_glue(&include_dir);
+        println!("cargo:rerun-if-changed=src/ffi/glue/glue.c");
+    }
+
+    let mut shim_cc = cc::Build::new();
+    shim_cc
+        .include(include_dir)
+        .define("COMPAT53_INCLUDE_SOURCE", None);
+    #[cfg(feature = "luajit")]
+    shim_cc.define("COMPAT53_LUAJIT", None);
+    shim_cc.file("src/ffi/shim/shim.c").compile("shim");
+
+    println!("cargo:rerun-if-changed=src/ffi/shim");
+    println!("cargo:rerun-if-changed=build");
 }

examples/async_http_client.rs

@@ -0,0 +1,83 @@
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use bstr::BString;
+use hyper::body::{Body as HyperBody, HttpBody as _};
+use hyper::Client as HyperClient;
+use tokio::sync::Mutex;
+
+use mlua::{Error, Lua, Result, UserData, UserDataMethods};
+
+#[derive(Clone)]
+struct BodyReader(Arc<Mutex<HyperBody>>);
+
+impl BodyReader {
+    fn new(body: HyperBody) -> Self {
+        BodyReader(Arc::new(Mutex::new(body)))
+    }
+}
+
+impl UserData for BodyReader {
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_async_method("read", |_, reader, ()| async move {
+            let mut reader = reader.0.lock().await;
+            if let Some(bytes) = reader.data().await {
+                let bytes = bytes.map_err(Error::external)?;
+                return Ok(Some(BString::from(bytes.as_ref())));
+            }
+            Ok(None)
+        });
+    }
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let lua = Lua::new();
+
+    let fetch_url = lua.create_async_function(|lua, uri: String| async move {
+        let client = HyperClient::new();
+        let uri = uri.parse().map_err(Error::external)?;
+        let resp = client.get(uri).await.map_err(Error::external)?;
+
+        let lua_resp = lua.create_table()?;
+        lua_resp.set("status", resp.status().as_u16())?;
+
+        let mut headers = HashMap::new();
+        for (key, value) in resp.headers().iter() {
+            headers
+                .entry(key.as_str())
+                .or_insert(Vec::new())
+                .push(value.to_str().unwrap());
+        }
+
+        lua_resp.set("headers", headers)?;
+        lua_resp.set("body", BodyReader::new(resp.into_body()))?;
+
+        Ok(lua_resp)
+    })?;
+
+    let globals = lua.globals();
+    globals.set("fetch_url", fetch_url)?;
+
+    let f = lua
+        .load(
+            r#"
+            local res = fetch_url(...)
+            print(res.status)
+            for key, vals in pairs(res.headers) do
+                for _, val in ipairs(vals) do
+                    print(key..": "..val)
+                end
+            end
+            repeat
+                local body = res.body:read()
+                if body then
+                    print(body)
+                end
+            until not body
+        "#,
+        )
+        .into_function()?;
+
+    f.call_async("http://httpbin.org/ip").await
+}

examples/async_http_reqwest.rs

@@ -0,0 +1,41 @@
+use mlua::{Error, Lua, LuaSerdeExt, Result};
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let lua = Lua::new();
+    let globals = lua.globals();
+    globals.set("null", lua.null())?;
+
+    let fetch_json = lua.create_async_function(|lua, uri: String| async move {
+        let resp = reqwest::get(&uri)
+            .await
+            .and_then(|resp| resp.error_for_status())
+            .map_err(Error::external)?;
+        let json = resp
+            .json::<serde_json::Value>()
+            .await
+            .map_err(Error::external)?;
+        lua.to_value(&json)
+    })?;
+    globals.set("fetch_json", fetch_json)?;
+
+    let f = lua
+        .load(
+            r#"
+            function print_r(t, indent)
+                local indent = indent or ''
+                for k, v in pairs(t) do
+                    io.write(indent, tostring(k))
+                    if type(v) == "table" then io.write(':\n') print_r(v, indent..'  ')
+                    else io.write(': ', v == null and "null" or tostring(v), '\n') end
+                end
+            end
+
+            local res = fetch_json(...)
+            print_r(res)
+        "#,
+        )
+        .into_function()?;
+
+    f.call_async("https://httpbin.org/anything?arg0=val0").await
+}

examples/async_http_server.rs

@@ -0,0 +1,101 @@
+use std::net::SocketAddr;
+use std::sync::Arc;
+
+use hyper::server::conn::AddrStream;
+use hyper::service::{make_service_fn, service_fn};
+use hyper::{Body, Request, Response, Server};
+
+use mlua::{Error, Function, Lua, Result, Table, UserData, UserDataMethods};
+
+#[derive(Clone)]
+struct LuaRequest(Arc<(SocketAddr, Request<Body>)>);
+
+impl UserData for LuaRequest {
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_method("remote_addr", |_lua, req, ()| Ok((req.0).0.to_string()));
+        methods.add_method("method", |_lua, req, ()| Ok((req.0).1.method().to_string()));
+    }
+}
+
+async fn run_server(handler: Function<'static>) -> Result<()> {
+    let make_svc = make_service_fn(|socket: &AddrStream| {
+        let remote_addr = socket.remote_addr();
+        let handler = handler.clone();
+        async move {
+            Ok::<_, Error>(service_fn(move |req: Request<Body>| {
+                let handler = handler.clone();
+                async move {
+                    let lua_req = LuaRequest(Arc::new((remote_addr, req)));
+                    let lua_resp: Table = handler.call_async(lua_req).await?;
+                    let body = lua_resp
+                        .get::<_, Option<String>>("body")?
+                        .unwrap_or_default();
+
+                    let mut resp = Response::builder()
+                        .status(lua_resp.get::<_, Option<u16>>("status")?.unwrap_or(200));
+
+                    if let Some(headers) = lua_resp.get::<_, Option<Table>>("headers")? {
+                        for pair in headers.pairs::<String, String>() {
+                            let (h, v) = pair?;
+                            resp = resp.header(&h, v);
+                        }
+                    }
+
+                    Ok::<_, Error>(resp.body(Body::from(body)).unwrap())
+                }
+            }))
+        }
+    });
+
+    let addr = ([127, 0, 0, 1], 3000).into();
+    let server = Server::bind(&addr).executor(LocalExec).serve(make_svc);
+
+    println!("Listening on http://{}", addr);
+
+    tokio::task::LocalSet::new()
+        .run_until(server)
+        .await
+        .map_err(Error::external)
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let lua = Lua::new().into_static();
+
+    let handler: Function = lua
+        .load(
+            r#"
+        function(req)
+            return {
+                status = 200,
+                headers = {
+                    ["X-Req-Method"] = req:method(),
+                    ["X-Remote-Addr"] = req:remote_addr(),
+                },
+                body = "Hello, World!"
+            }
+        end
+    "#,
+        )
+        .eval()?;
+
+    run_server(handler).await?;
+
+    // Consume the static reference and drop it.
+    // This is safe as long as we don't hold any other references to Lua
+    // or alive resources.
+    unsafe { Lua::from_static(lua) };
+    Ok(())
+}
+
+#[derive(Clone, Copy, Debug)]
+struct LocalExec;
+
+impl<F> hyper::rt::Executor<F> for LocalExec
+where
+    F: std::future::Future + 'static, // not requiring `Send`
+{
+    fn execute(&self, fut: F) {
+        tokio::task::spawn_local(fut);
+    }
+}

examples/async_tcp_server.rs

@@ -0,0 +1,128 @@
+use std::sync::Arc;
+
+use bstr::BString;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::{TcpListener, TcpStream};
+use tokio::sync::Mutex;
+use tokio::task;
+
+use mlua::{Function, Lua, Result, UserData, UserDataMethods};
+
+#[derive(Clone)]
+struct LuaTcp;
+
+#[derive(Clone)]
+struct LuaTcpListener(Arc<Mutex<TcpListener>>);
+
+#[derive(Clone)]
+struct LuaTcpStream(Arc<Mutex<TcpStream>>);
+
+impl UserData for LuaTcp {
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_async_function("bind", |_, addr: String| async move {
+            let listener = TcpListener::bind(addr).await?;
+            Ok(LuaTcpListener(Arc::new(Mutex::new(listener))))
+        });
+    }
+}
+
+impl UserData for LuaTcpListener {
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_async_method("accept", |_, listener, ()| async move {
+            let (stream, _) = listener.0.lock().await.accept().await?;
+            Ok(LuaTcpStream(Arc::new(Mutex::new(stream))))
+        });
+    }
+}
+
+impl UserData for LuaTcpStream {
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_async_method("peer_addr", |_, stream, ()| async move {
+            Ok(stream.0.lock().await.peer_addr()?.to_string())
+        });
+
+        methods.add_async_method("read", |_, stream, size: usize| async move {
+            let mut buf = vec![0; size];
+            let n = stream.0.lock().await.read(&mut buf).await?;
+            buf.truncate(n);
+            Ok(BString::from(buf))
+        });
+
+        methods.add_async_method("write", |_, stream, data: BString| async move {
+            let n = stream.0.lock().await.write(&data).await?;
+            Ok(n)
+        });
+
+        methods.add_async_method("close", |_, stream, ()| async move {
+            stream.0.lock().await.shutdown().await?;
+            Ok(())
+        });
+    }
+}
+
+async fn run_server(lua: &'static Lua) -> Result<()> {
+    let spawn = lua.create_function(move |_, func: Function| {
+        task::spawn_local(async move { func.call_async::<_, ()>(()).await });
+        Ok(())
+    })?;
+
+    let globals = lua.globals();
+    globals.set("tcp", LuaTcp)?;
+    globals.set("spawn", spawn)?;
+
+    let server = lua
+        .load(
+            r#"
+            local addr = ...
+            local listener = tcp.bind(addr)
+            print("listening on "..addr)
+
+            local accept_new = true
+            while true do
+                local stream = listener:accept()
+                local peer_addr = stream:peer_addr()
+                print("connected from "..peer_addr)
+
+                if not accept_new then
+                    return
+                end
+
+                spawn(function()
+                    while true do
+                        local data = stream:read(100)
+                        data = data:match("^%s*(.-)%s*$") -- trim
+                        print("["..peer_addr.."] "..data)
+                        if data == "bye" then
+                            stream:write("bye bye\n")
+                            stream:close()
+                            return
+                        end
+                        if data == "exit" then
+                            stream:close()
+                            accept_new = false
+                            return
+                        end
+                        stream:write("echo: "..data.."\n")
+                    end
+                end)
+            end
+        "#,
+        )
+        .into_function()?;
+
+    task::LocalSet::new()
+        .run_until(server.call_async::<_, ()>("0.0.0.0:1234"))
+        .await
+}
+
+#[tokio::main]
+async fn main() {
+    let lua = Lua::new().into_static();
+
+    run_server(lua).await.unwrap();
+
+    // Consume the static reference and drop it.
+    // This is safe as long as we don't hold any other references to Lua
+    // or alive resources.
+    unsafe { Lua::from_static(lua) };
+}

examples/guided_tour.rs

@@ -164,11 +164,10 @@ fn main() -> Result<()> {
             < f32::EPSILON
     );
 
-    // Normally, Rust types passed to `Lua` must be `Send`, because `Lua` itself is `Send`, and
-    // must be `'static`, because there is no way to be sure of their lifetime inside the Lua
-    // state.  There is, however, a limited way to lift both of these requirements.  You can
-    // call `Lua::scope` to create userdata and callbacks types that only live for as long
-    // as the call to scope, but do not have to be `Send` OR `'static`.
+    // Normally, Rust types passed to `Lua` must be `'static`, because there is no way to be
+    // sure of their lifetime inside the Lua state. There is, however, a limited way to lift this
+    // requirement. You can call `Lua::scope` to create userdata and callbacks types that only live
+    // for as long as the call to scope, but do not have to be `'static` (and `Send`).
 
     {
         let mut rust_val = 0;

examples/module/.cargo/config

@@ -0,0 +1,5 @@
+[target.x86_64-apple-darwin]
+rustflags = [
+  "-C", "link-arg=-undefined",
+  "-C", "link-arg=dynamic_lookup",
+]

examples/module/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "rust_module"
+version = "0.0.0"
+authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib"]
+
+[features]
+lua54 = ["mlua/lua54"]
+lua53 = ["mlua/lua53"]
+lua52 = ["mlua/lua52"]
+lua51 = ["mlua/lua51"]
+luajit = ["mlua/luajit"]
+vendored = ["mlua/vendored"]
+
+[dependencies]
+mlua = { path = "../..", features = ["module"] }

examples/module/src/lib.rs

@@ -0,0 +1,17 @@
+use mlua::prelude::*;
+
+fn sum(_: &Lua, (a, b): (i64, i64)) -> LuaResult<i64> {
+    Ok(a + b)
+}
+
+fn used_memory(lua: &Lua, _: ()) -> LuaResult<usize> {
+    Ok(lua.used_memory())
+}
+
+#[mlua::lua_module]
+fn rust_module(lua: &Lua) -> LuaResult<LuaTable> {
+    let exports = lua.create_table()?;
+    exports.set("sum", lua.create_function(sum)?)?;
+    exports.set("used_memory", lua.create_function(used_memory)?)?;
+    Ok(exports)
+}

examples/serialize.rs

@@ -0,0 +1,66 @@
+use mlua::{Error, Lua, LuaSerdeExt, Result, UserData, Value};
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+enum Transmission {
+    Manual,
+    Automatic,
+}
+
+#[derive(Serialize, Deserialize)]
+struct Engine {
+    v: u32,
+    kw: u32,
+}
+
+#[derive(Serialize, Deserialize)]
+struct Car {
+    active: bool,
+    model: String,
+    transmission: Transmission,
+    engine: Engine,
+}
+
+impl UserData for Car {}
+
+fn main() -> Result<()> {
+    let lua = Lua::new();
+    let globals = lua.globals();
+
+    // Create Car struct from a Lua table
+    let car: Car = lua.from_value(lua.load(r#"
+        {active = true, model = "Volkswagen Golf", transmission = "Automatic", engine = {v = 1499, kw = 90}}
+    "#).eval()?)?;
+
+    // Set it as (serializable) userdata
+    globals.set("null", lua.null())?;
+    globals.set("array_mt", lua.array_metatable())?;
+    globals.set("car", lua.create_ser_userdata(car)?)?;
+
+    // Create a Lua table with multiple data types
+    let val: Value = lua
+        .load(r#"{driver = "Boris", car = car, price = null, points = setmetatable({}, array_mt)}"#)
+        .eval()?;
+
+    // Serialize the table above to JSON
+    let json_str = serde_json::to_string(&val).map_err(Error::external)?;
+    println!("{}", json_str);
+
+    // Create Lua Value from JSON (or any serializable type)
+    let json = serde_json::json!({
+        "key": "value",
+        "null": null,
+        "array": [],
+    });
+    globals.set("json_value", lua.to_value(&json)?)?;
+    lua.load(
+        r#"
+        assert(json_value["key"] == "value")
+        assert(json_value["null"] == null)
+        assert(#(json_value["array"]) == 0)
+    "#,
+    )
+    .exec()?;
+
+    Ok(())
+}

mlua_derive/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "mlua_derive"
-version = "0.2.0"
-authors = ["Aleksandr Orlenko <zxteam@protonmail.com>"]
+version = "0.5.0"
+authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
 edition = "2018"
 description = "Procedural macros for the mlua crate."
 repository = "https://github.com/khvzak/mlua"

mlua_derive/src/lib.rs

@@ -21,6 +21,8 @@ pub fn lua_module(attr: TokenStream, item: TokenStream) -> TokenStream {
     let ext_entrypoint_name = Ident::new(&format!("luaopen_{}", item.sig.ident), Span::call_site());
 
     let wrapped = quote_spanned! { span =>
+        mlua::require_module_feature!();
+
         #[no_mangle]
         unsafe extern "C" fn #ext_entrypoint_name(state: *mut mlua::lua_State) -> std::os::raw::c_int {
             #item

src/conversion.rs

@@ -1,4 +1,5 @@
-use std::collections::{BTreeMap, HashMap};
+use std::borrow::Cow;
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::ffi::{CStr, CString};
 use std::hash::{BuildHasher, Hash};
 use std::string::String as StdString;
@@ -12,7 +13,7 @@ use crate::lua::Lua;
 use crate::string::String;
 use crate::table::Table;
 use crate::thread::Thread;
-use crate::types::{LightUserData, Number};
+use crate::types::{LightUserData, MaybeSend};
 use crate::userdata::{AnyUserData, UserData};
 use crate::value::{FromLua, Nil, ToLua, Value};
 
@@ -122,7 +123,7 @@ impl<'lua> FromLua<'lua> for AnyUserData<'lua> {
     }
 }
 
-impl<'lua, T: 'static + Send + UserData> ToLua<'lua> for T {
+impl<'lua, T: 'static + MaybeSend + UserData> ToLua<'lua> for T {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::UserData(lua.create_userdata(self)?))
     }
@@ -167,7 +168,7 @@ impl<'lua> ToLua<'lua> for bool {
 }
 
 impl<'lua> FromLua<'lua> for bool {
-    fn from_lua(v: Value, _: &'lua Lua) -> Result<Self> {
+    fn from_lua(v: Value<'lua>, _: &'lua Lua) -> Result<Self> {
         match v {
             Value::Nil => Ok(false),
             Value::Boolean(b) => Ok(b),
@@ -183,7 +184,7 @@ impl<'lua> ToLua<'lua> for LightUserData {
 }
 
 impl<'lua> FromLua<'lua> for LightUserData {
-    fn from_lua(value: Value, _: &'lua Lua) -> Result<Self> {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Self> {
         match value {
             Value::LightUserData(ud) => Ok(ud),
             _ => Err(Error::FromLuaConversionError {
@@ -216,12 +217,40 @@ impl<'lua> FromLua<'lua> for StdString {
     }
 }
 
-impl<'lua, 'a> ToLua<'lua> for &'a str {
+impl<'lua> ToLua<'lua> for &str {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::String(lua.create_string(self)?))
     }
 }
 
+impl<'lua> ToLua<'lua> for Cow<'_, str> {
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::String(lua.create_string(self.as_bytes())?))
+    }
+}
+
+impl<'lua> ToLua<'lua> for Box<str> {
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::String(lua.create_string(&*self)?))
+    }
+}
+
+impl<'lua> FromLua<'lua> for Box<str> {
+    fn from_lua(value: Value<'lua>, lua: &'lua Lua) -> Result<Self> {
+        let ty = value.type_name();
+        Ok(lua
+            .coerce_string(value)?
+            .ok_or_else(|| Error::FromLuaConversionError {
+                from: ty,
+                to: "Box<str>",
+                message: Some("expected string or number".to_string()),
+            })?
+            .to_str()?
+            .to_owned()
+            .into_boxed_str())
+    }
+}
+
 impl<'lua> ToLua<'lua> for CString {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::String(lua.create_string(self.as_bytes())?))
@@ -250,13 +279,19 @@ impl<'lua> FromLua<'lua> for CString {
     }
 }
 
-impl<'lua, 'a> ToLua<'lua> for &'a CStr {
+impl<'lua> ToLua<'lua> for &CStr {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::String(lua.create_string(self.to_bytes())?))
     }
 }
 
-impl<'lua, 'a> ToLua<'lua> for BString {
+impl<'lua> ToLua<'lua> for Cow<'_, CStr> {
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::String(lua.create_string(self.to_bytes())?))
+    }
+}
+
+impl<'lua> ToLua<'lua> for BString {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::String(lua.create_string(&self)?))
     }
@@ -278,7 +313,7 @@ impl<'lua> FromLua<'lua> for BString {
     }
 }
 
-impl<'lua, 'a> ToLua<'lua> for &BStr {
+impl<'lua> ToLua<'lua> for &BStr {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::String(lua.create_string(&self)?))
     }
@@ -345,7 +380,13 @@ macro_rules! lua_convert_float {
     ($x:ty) => {
         impl<'lua> ToLua<'lua> for $x {
             fn to_lua(self, _: &'lua Lua) -> Result<Value<'lua>> {
-                Ok(Value::Number(self as Number))
+                cast(self)
+                    .ok_or_else(|| Error::ToLuaConversionError {
+                        from: stringify!($x),
+                        to: "number",
+                        message: Some("out of range".to_string()),
+                    })
+                    .map(Value::Number)
             }
         }
 
@@ -373,6 +414,70 @@ macro_rules! lua_convert_float {
 lua_convert_float!(f32);
 lua_convert_float!(f64);
 
+impl<'lua, T> ToLua<'lua> for &[T]
+where
+    T: Clone + ToLua<'lua>,
+{
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::Table(
+            lua.create_sequence_from(self.iter().cloned())?,
+        ))
+    }
+}
+
+macro_rules! lua_convert_array {
+    ($($N:literal)+) => {
+        $(
+            impl<'lua, T> ToLua<'lua> for [T; $N]
+            where
+                T: Clone + ToLua<'lua>,
+            {
+                fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+                    (&self).to_lua(lua)
+                }
+            }
+
+            impl<'lua, T> ToLua<'lua> for &[T; $N]
+            where
+                T: Clone + ToLua<'lua>,
+            {
+                fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+                    Ok(Value::Table(
+                        lua.create_sequence_from(self.iter().cloned())?,
+                    ))
+                }
+            }
+        )+
+    }
+}
+
+lua_convert_array! {
+    0  1  2  3  4  5  6  7  8  9
+   10 11 12 13 14 15 16 17 18 19
+   20 21 22 23 24 25 26 27 28 29
+   30 31 32
+}
+
+impl<'lua, T: ToLua<'lua>> ToLua<'lua> for Box<[T]> {
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::Table(lua.create_sequence_from(self.into_vec())?))
+    }
+}
+
+impl<'lua, T: FromLua<'lua>> FromLua<'lua> for Box<[T]> {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Self> {
+        if let Value::Table(table) = value {
+            table.sequence_values().collect()
+        } else {
+            Err(Error::FromLuaConversionError {
+                from: value.type_name(),
+                to: "Box<[T]>",
+                message: Some("expected table".to_string()),
+            })
+        }
+    }
+}
+
 impl<'lua, T: ToLua<'lua>> ToLua<'lua> for Vec<T> {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         Ok(Value::Table(lua.create_sequence_from(self)?))
@@ -437,6 +542,56 @@ impl<'lua, K: Ord + FromLua<'lua>, V: FromLua<'lua>> FromLua<'lua> for BTreeMap<
     }
 }
 
+impl<'lua, T: Eq + Hash + ToLua<'lua>, S: BuildHasher> ToLua<'lua> for HashSet<T, S> {
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::Table(lua.create_table_from(
+            self.into_iter().map(|val| (val, true)),
+        )?))
+    }
+}
+
+impl<'lua, T: Eq + Hash + FromLua<'lua>, S: BuildHasher + Default> FromLua<'lua> for HashSet<T, S> {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Self> {
+        if let Value::Table(table) = value {
+            table
+                .pairs::<T, Value<'lua>>()
+                .map(|res| res.map(|(k, _)| k))
+                .collect()
+        } else {
+            Err(Error::FromLuaConversionError {
+                from: value.type_name(),
+                to: "HashSet",
+                message: Some("expected table".to_string()),
+            })
+        }
+    }
+}
+
+impl<'lua, T: Ord + ToLua<'lua>> ToLua<'lua> for BTreeSet<T> {
+    fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
+        Ok(Value::Table(lua.create_table_from(
+            self.into_iter().map(|val| (val, true)),
+        )?))
+    }
+}
+
+impl<'lua, T: Ord + FromLua<'lua>> FromLua<'lua> for BTreeSet<T> {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Self> {
+        if let Value::Table(table) = value {
+            table
+                .pairs::<T, Value<'lua>>()
+                .map(|res| res.map(|(k, _)| k))
+                .collect()
+        } else {
+            Err(Error::FromLuaConversionError {
+                from: value.type_name(),
+                to: "BTreeSet",
+                message: Some("expected table".to_string()),
+            })
+        }
+    }
+}
+
 impl<'lua, T: ToLua<'lua>> ToLua<'lua> for Option<T> {
     fn to_lua(self, lua: &'lua Lua) -> Result<Value<'lua>> {
         match self {

src/error.rs

@@ -1,11 +1,15 @@
 use std::error::Error as StdError;
 use std::fmt;
+use std::io::Error as IoError;
+use std::net::AddrParseError;
 use std::result::Result as StdResult;
+use std::str::Utf8Error;
 use std::string::String as StdString;
 use std::sync::Arc;
 
 /// Error type returned by `mlua` methods.
 #[derive(Debug, Clone)]
+#[non_exhaustive]
 pub enum Error {
     /// Syntax error while parsing Lua source code.
     SyntaxError {
@@ -33,6 +37,18 @@ pub enum Error {
     /// The Lua VM returns this error when there is an error running a `__gc` metamethod.
     #[cfg(any(feature = "lua53", feature = "lua52"))]
     GarbageCollectorError(StdString),
+    /// Potentially unsafe action in safe mode.
+    SafetyError(StdString),
+    /// Setting memory limit is not available.
+    ///
+    /// This error can only happen when Lua state was not created by us and does not have the
+    /// custom allocator attached.
+    MemoryLimitNotAvailable,
+    /// Main thread is not available.
+    ///
+    /// This error can only happen in Lua5.1/LuaJIT module mode, when module loaded within a coroutine.
+    /// These Lua versions does not have `LUA_RIDX_MAINTHREAD` registry key.
+    MainThreadNotAvailable,
     /// A mutable callback has triggered Lua code that has called the same mutable callback again.
     ///
     /// This is an error because a mutable callback can only be borrowed mutably once.
@@ -90,6 +106,13 @@ pub enum Error {
     /// [`AnyUserData`]: struct.AnyUserData.html
     /// [`UserDataMethods`]: trait.UserDataMethods.html
     UserDataTypeMismatch,
+    /// An [`AnyUserData`] borrow failed because it has been destructed.
+    ///
+    /// This error can happen either due to to being destructed in a previous __gc, or due to being
+    /// destructed from exiting a `Lua::scope` call.
+    ///
+    /// [`AnyUserData`]: struct.AnyUserData.html
+    UserDataDestructed,
     /// An [`AnyUserData`] immutable borrow failed because it is already borrowed mutably.
     ///
     /// This error can occur when a method on a [`UserData`] type calls back into Lua, which then
@@ -108,6 +131,18 @@ pub enum Error {
     /// [`AnyUserData`]: struct.AnyUserData.html
     /// [`UserData`]: trait.UserData.html
     UserDataBorrowMutError,
+    /// A [`MetaMethod`] operation is restricted (typically for `__gc` or `__metatable`).
+    ///
+    /// [`MetaMethod`]: enum.MetaMethod.html
+    MetaMethodRestricted(StdString),
+    /// A [`MetaMethod`] (eg. `__index` or `__newindex`) has invalid type.
+    ///
+    /// [`MetaMethod`]: enum.MetaMethod.html
+    MetaMethodTypeError {
+        method: StdString,
+        type_name: &'static str,
+        message: Option<StdString>,
+    },
     /// A `RegistryKey` produced from a different Lua state was used.
     MismatchedRegistryKey,
     /// A Rust callback returned `Err`, raising the contained `Error` as a Lua error.
@@ -117,6 +152,19 @@ pub enum Error {
         /// Original error returned by the Rust code.
         cause: Arc<Error>,
     },
+    /// A Rust panic that was previosly resumed, returned again.
+    ///
+    /// This error can occur only when a Rust panic resumed previously was recovered
+    /// and returned again.
+    PreviouslyResumedPanic,
+    /// Serialization error.
+    #[cfg(feature = "serialize")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "serialize")))]
+    SerializeError(StdString),
+    /// Deserialization error.
+    #[cfg(feature = "serialize")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "serialize")))]
+    DeserializeError(StdString),
     /// A custom error.
     ///
     /// This can be used for returning user-defined errors from callbacks.
@@ -124,7 +172,10 @@ pub enum Error {
     /// Returning `Err(ExternalError(...))` from a Rust callback will raise the error as a Lua
     /// error. The Rust code that originally invoked the Lua code then receives a `CallbackError`,
     /// from which the original error (and a stack traceback) can be recovered.
+    #[cfg(feature = "send")]
     ExternalError(Arc<dyn StdError + Send + Sync>),
+    #[cfg(not(feature = "send"))]
+    ExternalError(Arc<dyn StdError>),
 }
 
 /// A specialized `Result` type used by `mlua`'s API.
@@ -142,6 +193,15 @@ impl fmt::Display for Error {
             Error::GarbageCollectorError(ref msg) => {
                 write!(fmt, "garbage collector error: {}", msg)
             }
+            Error::SafetyError(ref msg) => {
+                write!(fmt, "safety error: {}", msg)
+            },
+            Error::MemoryLimitNotAvailable => {
+                write!(fmt, "setting memory limit is not available")
+            }
+            Error::MainThreadNotAvailable => {
+                write!(fmt, "main thread is not available in Lua 5.1")
+            }
             Error::RecursiveMutCallback => write!(fmt, "mutable callback called recursively"),
             Error::CallbackDestructed => write!(
                 fmt,
@@ -155,22 +215,14 @@ impl fmt::Display for Error {
                 fmt,
                 "too many arguments to Function::bind"
             ),
-            Error::ToLuaConversionError {
-                from,
-                to,
-                ref message,
-            } => {
+            Error::ToLuaConversionError { from, to, ref message } => {
                 write!(fmt, "error converting {} to Lua {}", from, to)?;
                 match *message {
                     None => Ok(()),
                     Some(ref message) => write!(fmt, " ({})", message),
                 }
             }
-            Error::FromLuaConversionError {
-                from,
-                to,
-                ref message,
-            } => {
+            Error::FromLuaConversionError { from, to, ref message } => {
                 write!(fmt, "error converting Lua {} to {}", from, to)?;
                 match *message {
                     None => Ok(()),
@@ -179,15 +231,35 @@ impl fmt::Display for Error {
             }
             Error::CoroutineInactive => write!(fmt, "cannot resume inactive coroutine"),
             Error::UserDataTypeMismatch => write!(fmt, "userdata is not expected type"),
+            Error::UserDataDestructed => write!(fmt, "userdata has been destructed"),
             Error::UserDataBorrowError => write!(fmt, "userdata already mutably borrowed"),
             Error::UserDataBorrowMutError => write!(fmt, "userdata already borrowed"),
+            Error::MetaMethodRestricted(ref method) => write!(fmt, "metamethod {} is restricted", method),
+            Error::MetaMethodTypeError { ref method, type_name, ref message } => {
+                write!(fmt, "metamethod {} has unsupported type {}", method, type_name)?;
+                match *message {
+                    None => Ok(()),
+                    Some(ref message) => write!(fmt, " ({})", message),
+                }
+            }
             Error::MismatchedRegistryKey => {
                 write!(fmt, "RegistryKey used from different Lua state")
             }
-            Error::CallbackError { ref traceback, ref cause } => {
-                write!(fmt, "callback error: {}: {}", cause, traceback)
+            Error::CallbackError { ref traceback, .. } => {
+                write!(fmt, "callback error: {}", traceback)
             }
-            Error::ExternalError(ref err) => write!(fmt, "external error: {}", err),
+            Error::PreviouslyResumedPanic => {
+                write!(fmt, "previously resumed panic returned again")
+            }
+            #[cfg(feature = "serialize")]
+            Error::SerializeError(ref err) => {
+                write!(fmt, "serialize error: {}", err)
+            },
+            #[cfg(feature = "serialize")]
+            Error::DeserializeError(ref err) => {
+                write!(fmt, "deserialize error: {}", err)
+            },
+            Error::ExternalError(ref err) => write!(fmt, "{}", err),
         }
     }
 }
@@ -196,26 +268,37 @@ impl StdError for Error {
     fn source(&self) -> Option<&(dyn StdError + 'static)> {
         match *self {
             Error::CallbackError { ref cause, .. } => Some(cause.as_ref()),
-            Error::ExternalError(ref err) => Some(err.as_ref()),
+            Error::ExternalError(ref err) => err.source(),
             _ => None,
         }
     }
 }
 
 impl Error {
+    #[cfg(feature = "send")]
     pub fn external<T: Into<Box<dyn StdError + Send + Sync>>>(err: T) -> Error {
         Error::ExternalError(err.into().into())
     }
+
+    #[cfg(not(feature = "send"))]
+    pub fn external<T: Into<Box<dyn StdError>>>(err: T) -> Error {
+        Error::ExternalError(err.into().into())
+    }
 }
 
 pub trait ExternalError {
     fn to_lua_err(self) -> Error;
 }
 
-impl<E> ExternalError for E
-where
-    E: Into<Box<dyn StdError + Send + Sync>>,
-{
+#[cfg(feature = "send")]
+impl<E: Into<Box<dyn StdError + Send + Sync>>> ExternalError for E {
+    fn to_lua_err(self) -> Error {
+        Error::external(self)
+    }
+}
+
+#[cfg(not(feature = "send"))]
+impl<E: Into<Box<dyn StdError>>> ExternalError for E {
     fn to_lua_err(self) -> Error {
         Error::external(self)
     }
@@ -233,3 +316,35 @@ where
         self.map_err(|e| e.to_lua_err())
     }
 }
+
+impl std::convert::From<AddrParseError> for Error {
+    fn from(err: AddrParseError) -> Self {
+        Error::external(err)
+    }
+}
+
+impl std::convert::From<IoError> for Error {
+    fn from(err: IoError) -> Self {
+        Error::external(err)
+    }
+}
+
+impl std::convert::From<Utf8Error> for Error {
+    fn from(err: Utf8Error) -> Self {
+        Error::external(err)
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl serde::ser::Error for Error {
+    fn custom<T: fmt::Display>(msg: T) -> Self {
+        Self::SerializeError(msg.to_string())
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl serde::de::Error for Error {
+    fn custom<T: fmt::Display>(msg: T) -> Self {
+        Self::DeserializeError(msg.to_string())
+    }
+}

src/ffi/compat53.rs

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -22,6 +22,8 @@
 
 // Based on github.com/keplerproject/lua-compat-5.3
 
+#![allow(clippy::needless_return)]
+
 use std::ffi::CStr;
 use std::mem;
 use std::os::raw::{c_char, c_int, c_void};
@@ -42,18 +44,18 @@ use super::lua::{
     lua_createtable, lua_dump_old, lua_error, lua_getfield_old, lua_getstack, lua_gettable_old,
     lua_gettop, lua_insert, lua_isstring, lua_istable, lua_newuserdata, lua_pop, lua_pushboolean,
     lua_pushcfunction, lua_pushfstring, lua_pushinteger, lua_pushliteral, lua_pushlstring_old,
-    lua_pushnumber, lua_pushthread, lua_pushvalue, lua_rawget_old, lua_rawgeti_old, lua_rawset,
-    lua_replace, lua_setfield, lua_setglobal, lua_setmetatable, lua_settable, lua_toboolean,
-    lua_tointeger, lua_tolstring, lua_tonumber, lua_topointer, lua_tostring, lua_touserdata,
-    lua_type, lua_typename,
+    lua_pushnil, lua_pushnumber, lua_pushthread, lua_pushvalue, lua_rawget_old, lua_rawgeti_old,
+    lua_rawset, lua_replace, lua_setfield, lua_setglobal, lua_setmetatable, lua_settable,
+    lua_toboolean, lua_tointeger, lua_tolstring, lua_tonumber, lua_topointer, lua_tostring,
+    lua_touserdata, lua_type, lua_typename,
 };
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
 use super::lua::{
     lua_checkstack, lua_concat, lua_equal, lua_getfenv, lua_getinfo, lua_getmetatable,
     lua_isnumber, lua_lessthan, lua_newtable, lua_next, lua_objlen, lua_pushcclosure,
-    lua_pushlightuserdata, lua_pushnil, lua_pushstring_old, lua_rawequal, lua_remove,
-    lua_resume_old, lua_setfenv, lua_settop, LUA_OPADD, LUA_OPUNM,
+    lua_pushlightuserdata, lua_pushstring_old, lua_rawequal, lua_remove, lua_resume_old,
+    lua_setfenv, lua_settop, LUA_OPADD, LUA_OPUNM,
 };
 
 #[cfg(feature = "lua52")]
@@ -114,7 +116,7 @@ unsafe fn compat53_checkmode(
         }
     }
 
-    if mode != ptr::null() && strchr(mode, *modename) == ptr::null() {
+    if !mode.is_null() && strchr(mode, *modename).is_null() {
         lua_pushfstring(
             L,
             cstr!("attempt to load a %s chunk (mode is '%s')"),
@@ -226,6 +228,7 @@ pub fn lua_upvalueindex(i: c_int) -> c_int {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_absindex(L: *mut lua_State, mut idx: c_int) -> c_int {
     if idx < 0 && idx > lua::LUA_REGISTRYINDEX {
         idx += lua_gettop(L) + 1;
@@ -234,7 +237,7 @@ pub unsafe fn lua_absindex(L: *mut lua_State, mut idx: c_int) -> c_int {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
-static COMPAT53_ARITH_CODE: &'static str = r#"
+static COMPAT53_ARITH_CODE: &str = r#"
 local op,a,b=...
 if op == 0 then return a+b
 elseif op == 1 then return a-b
@@ -248,6 +251,7 @@ end
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
 pub unsafe fn lua_arith(L: *mut lua_State, op: c_int) {
+    #[allow(clippy::manual_range_contains)]
     if op < LUA_OPADD || op > LUA_OPUNM {
         luaL_error(L, cstr!("invalid 'op' argument for lua_arith"));
     }
@@ -276,6 +280,7 @@ pub unsafe fn lua_rotate(L: *mut lua_State, mut idx: c_int, mut n: c_int) {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_copy(L: *mut lua_State, fromidx: c_int, toidx: c_int) {
     let abs_to = lua_absindex(L, toidx);
     luaL_checkstack(L, 1, cstr!("not enough stack slots"));
@@ -283,11 +288,12 @@ pub unsafe fn lua_copy(L: *mut lua_State, fromidx: c_int, toidx: c_int) {
     lua_replace(L, abs_to);
 }
 
+#[inline(always)]
 pub unsafe fn lua_isinteger(L: *mut lua_State, idx: c_int) -> c_int {
     if lua_type(L, idx) == lua::LUA_TNUMBER {
         let n = lua_tonumber(L, idx);
         let i = lua_tointeger(L, idx);
-        if i as f64 == n {
+        if (n - i as lua_Number).abs() < lua_Number::EPSILON {
             return 1;
         }
     }
@@ -295,9 +301,10 @@ pub unsafe fn lua_isinteger(L: *mut lua_State, idx: c_int) -> c_int {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_tonumberx(L: *mut lua_State, i: c_int, isnum: *mut c_int) -> lua_Number {
     let n = lua_tonumber(L, i);
-    if isnum != ptr::null_mut() {
+    if !isnum.is_null() {
         *isnum = if n != 0.0 || lua_isnumber(L, i) != 0 {
             1
         } else {
@@ -309,29 +316,31 @@ pub unsafe fn lua_tonumberx(L: *mut lua_State, i: c_int, isnum: *mut c_int) -> l
 
 // Implemented for Lua 5.2 as well
 // See https://github.com/keplerproject/lua-compat-5.3/issues/40
+#[inline(always)]
 pub unsafe fn lua_tointegerx(L: *mut lua_State, i: c_int, isnum: *mut c_int) -> lua_Integer {
     let mut ok = 0;
     let n = lua_tonumberx(L, i, &mut ok);
-    if ok != 0 {
-        if n == n as lua_Integer as lua_Number {
-            if isnum != ptr::null_mut() {
-                *isnum = 1;
-            }
-            return n as lua_Integer;
+    let n_int = n as lua_Integer;
+    if ok != 0 && (n - n_int as lua_Number).abs() < lua_Number::EPSILON {
+        if !isnum.is_null() {
+            *isnum = 1;
         }
+        return n_int;
     }
-    if isnum != ptr::null_mut() {
+    if !isnum.is_null() {
         *isnum = 0;
     }
     return 0;
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_rawlen(L: *mut lua_State, idx: c_int) -> usize {
     lua_objlen(L, idx)
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_compare(L: *mut lua_State, mut idx1: c_int, mut idx2: c_int, op: c_int) -> c_int {
     match op {
         lua::LUA_OPEQ => lua_equal(L, idx1, idx2),
@@ -352,6 +361,7 @@ pub unsafe fn lua_compare(L: *mut lua_State, mut idx1: c_int, mut idx2: c_int, o
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_pushlstring(L: *mut lua_State, s: *const c_char, l: usize) -> *const c_char {
     if l == 0 {
         lua_pushlstring_old(L, cstr!(""), 0);
@@ -362,6 +372,7 @@ pub unsafe fn lua_pushlstring(L: *mut lua_State, s: *const c_char, l: usize) ->
 }
 
 #[cfg(feature = "lua52")]
+#[inline(always)]
 pub unsafe fn lua_pushlstring(L: *mut lua_State, s: *const c_char, l: usize) -> *const c_char {
     if l == 0 {
         lua_pushlstring_old(L, cstr!(""), 0)
@@ -371,27 +382,32 @@ pub unsafe fn lua_pushlstring(L: *mut lua_State, s: *const c_char, l: usize) ->
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_pushstring(L: *mut lua_State, s: *const c_char) -> *const c_char {
     lua_pushstring_old(L, s);
     lua_tostring(L, -1)
 }
 
 #[cfg(feature = "lua52")]
+#[inline(always)]
 pub unsafe fn lua_getglobal(L: *mut lua_State, var: *const c_char) -> c_int {
     lua_getglobal_old(L, var);
     lua_type(L, -1)
 }
 
+#[inline(always)]
 pub unsafe fn lua_gettable(L: *mut lua_State, idx: c_int) -> c_int {
     lua_gettable_old(L, idx);
     lua_type(L, -1)
 }
 
+#[inline(always)]
 pub unsafe fn lua_getfield(L: *mut lua_State, idx: c_int, k: *const c_char) -> c_int {
     lua_getfield_old(L, idx, k);
     lua_type(L, -1)
 }
 
+#[inline(always)]
 pub unsafe fn lua_geti(L: *mut lua_State, mut idx: c_int, n: lua_Integer) -> c_int {
     idx = lua_absindex(L, idx);
     lua_pushinteger(L, n);
@@ -400,18 +416,21 @@ pub unsafe fn lua_geti(L: *mut lua_State, mut idx: c_int, n: lua_Integer) -> c_i
 }
 
 // A new version which returns c_int
+#[inline(always)]
 pub unsafe fn lua_rawget(L: *mut lua_State, idx: c_int) -> c_int {
     lua_rawget_old(L, idx);
     lua_type(L, -1)
 }
 
 // A new version which returns c_int
+#[inline(always)]
 pub unsafe fn lua_rawgeti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_int {
     lua_rawgeti_old(L, idx, n);
     lua_type(L, -1)
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_rawgetp(L: *mut lua_State, idx: c_int, p: *const c_void) -> c_int {
     let abs_i = lua_absindex(L, idx);
     lua_pushlightuserdata(L, p as *mut c_void);
@@ -420,23 +439,27 @@ pub unsafe fn lua_rawgetp(L: *mut lua_State, idx: c_int, p: *const c_void) -> c_
 }
 
 #[cfg(feature = "lua52")]
+#[inline(always)]
 pub unsafe fn lua_rawgetp(L: *mut lua_State, idx: c_int, p: *const c_void) -> c_int {
     lua_rawgetp_old(L, idx, p);
     lua_type(L, -1)
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_getuservalue(L: *mut lua_State, idx: c_int) -> c_int {
     lua_getfenv(L, idx);
     lua_type(L, -1)
 }
 
 #[cfg(feature = "lua52")]
+#[inline(always)]
 pub unsafe fn lua_getuservalue(L: *mut lua_State, idx: c_int) -> c_int {
     lua_getuservalue_old(L, idx);
     lua_type(L, -1)
 }
 
+#[inline(always)]
 pub unsafe fn lua_seti(L: *mut lua_State, mut idx: c_int, n: lua_Integer) {
     luaL_checkstack(L, 1, cstr!("not enough stack slots available"));
     idx = lua_absindex(L, idx);
@@ -446,6 +469,7 @@ pub unsafe fn lua_seti(L: *mut lua_State, mut idx: c_int, n: lua_Integer) {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_rawsetp(L: *mut lua_State, idx: c_int, p: *const c_void) {
     let abs_i = lua_absindex(L, idx);
     luaL_checkstack(L, 1, cstr!("not enough stack slots"));
@@ -455,11 +479,13 @@ pub unsafe fn lua_rawsetp(L: *mut lua_State, idx: c_int, p: *const c_void) {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_setuservalue(L: *mut lua_State, idx: c_int) {
     luaL_checktype(L, -1, lua::LUA_TTABLE);
     lua_setfenv(L, idx);
 }
 
+#[inline(always)]
 pub unsafe fn lua_dump(
     L: *mut lua_State,
     writer: lua_Writer,
@@ -470,11 +496,13 @@ pub unsafe fn lua_dump(
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_resume(L: *mut lua_State, _from: *mut lua_State, narg: c_int) -> c_int {
     lua_resume_old(L, narg)
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn lua_len(L: *mut lua_State, idx: c_int) {
     match lua_type(L, idx) {
         lua::LUA_TSTRING => {
@@ -496,6 +524,7 @@ pub unsafe fn lua_len(L: *mut lua_State, idx: c_int) {
     }
 }
 
+#[inline(always)]
 pub unsafe fn lua_stringtonumber(L: *mut lua_State, s: *const c_char) -> usize {
     use std::str::FromStr;
 
@@ -531,7 +560,7 @@ pub unsafe fn lua_getextraspace(L: *mut lua_State) -> *mut c_void {
     let is_main = lua_pushthread(L);
     lua_rawget(L, -2);
     let mut _ptr = lua_touserdata(L, -1);
-    if _ptr == ptr::null_mut() {
+    if _ptr.is_null() {
         lua_pop(L, 1);
         _ptr = lua_newuserdata(L, LUA_EXTRASPACE as usize);
         if is_main != 0 {
@@ -547,7 +576,7 @@ pub unsafe fn lua_getextraspace(L: *mut lua_State) -> *mut c_void {
             lua_pushboolean(L, 1);
             lua_rawget(L, -3);
             let mptr = lua_touserdata(L, -1);
-            if mptr != ptr::null_mut() {
+            if !mptr.is_null() {
                 ptr::copy_nonoverlapping(mptr, _ptr, LUA_EXTRASPACE as usize)
             } else {
                 ptr::write_bytes(_ptr, 0, LUA_EXTRASPACE as usize);
@@ -573,9 +602,10 @@ pub unsafe fn lua_pushglobaltable(L: *mut lua_State) {
 //
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn luaL_checkstack(L: *mut lua_State, sz: c_int, msg: *const c_char) {
     if lua_checkstack(L, sz + lua::LUA_MINSTACK) == 0 {
-        if msg != ptr::null() {
+        if !msg.is_null() {
             luaL_error(L, cstr!("stack overflow (%s)"), msg);
         } else {
             lua_pushliteral(L, "stack overflow");
@@ -588,6 +618,7 @@ pub unsafe fn luaL_checkversion(_L: *mut lua_State) {
     // Void
 }
 
+#[inline(always)]
 pub unsafe fn luaL_getmetafield(L: *mut lua_State, obj: c_int, e: *const c_char) -> c_int {
     if luaL_getmetafield_old(L, obj, e) != 0 {
         lua_type(L, -1)
@@ -596,6 +627,7 @@ pub unsafe fn luaL_getmetafield(L: *mut lua_State, obj: c_int, e: *const c_char)
     }
 }
 
+#[inline(always)]
 pub unsafe fn luaL_newmetatable(L: *mut lua_State, tname: *const c_char) -> c_int {
     if luaL_newmetatable_old(L, tname) != 0 {
         lua_pushstring(L, tname);
@@ -607,6 +639,7 @@ pub unsafe fn luaL_newmetatable(L: *mut lua_State, tname: *const c_char) -> c_in
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn luaL_loadbufferx(
     L: *mut lua_State,
     buff: *const c_char,
@@ -626,6 +659,7 @@ pub unsafe fn luaL_loadbufferx(
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn luaL_len(L: *mut lua_State, idx: c_int) -> lua_Integer {
     let mut isnum = 0;
     luaL_checkstack(L, 1, cstr!("not enough stack slots"));
@@ -654,7 +688,7 @@ pub unsafe fn luaL_traceback(
         0
     };
 
-    if msg != ptr::null() {
+    if !msg.is_null() {
         lua_pushfstring(L, cstr!("%s\n"), msg);
     }
     lua_pushliteral(L, "stack traceback:");
@@ -666,7 +700,7 @@ pub unsafe fn luaL_traceback(
             level = numlevels - COMPAT53_LEVELS2; // and skip to last ones
         } else {
             lua_getinfo(L1, cstr!("Slnt"), &mut ar);
-            lua_pushfstring(L, cstr!("\n\t%s:"), cstr!("ok") /*ar.short_src*/);
+            lua_pushfstring(L, cstr!("\n\t%s:"), ar.short_src.as_ptr());
             if ar.currentline > 0 {
                 lua_pushfstring(L, cstr!("%d:"), ar.currentline);
             }
@@ -708,15 +742,14 @@ pub unsafe fn luaL_tolstring(L: *mut lua_State, idx: c_int, len: *mut usize) ->
                 }
             }
         };
-    } else {
-        if lua_isstring(L, -1) == 0 {
-            luaL_error(L, cstr!("'__tostring' must return a string"));
-        }
+    } else if lua_isstring(L, -1) == 0 {
+        luaL_error(L, cstr!("'__tostring' must return a string"));
     }
     lua_tolstring(L, -1, len)
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn luaL_setmetatable(L: *mut lua_State, tname: *const c_char) {
     luaL_checkstack(L, 1, cstr!("not enough stack slots"));
     luaL_getmetatable(L, tname);
@@ -724,10 +757,11 @@ pub unsafe fn luaL_setmetatable(L: *mut lua_State, tname: *const c_char) {
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn luaL_testudata(L: *mut lua_State, i: c_int, tname: *const c_char) -> *mut c_void {
     let mut p = lua_touserdata(L, i);
     luaL_checkstack(L, 2, cstr!("not enough stack slots"));
-    if p == ptr::null_mut() || lua_getmetatable(L, i) == 0 {
+    if p.is_null() || lua_getmetatable(L, i) == 0 {
         return ptr::null_mut();
     } else {
         luaL_getmetatable(L, tname);
@@ -741,9 +775,10 @@ pub unsafe fn luaL_testudata(L: *mut lua_State, i: c_int, tname: *const c_char)
 }
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
+#[inline(always)]
 pub unsafe fn luaL_setfuncs(L: *mut lua_State, mut l: *const luaL_Reg, nup: c_int) {
     luaL_checkstack(L, nup + 1, cstr!("too many upvalues"));
-    while (*l).name != ptr::null() {
+    while !(*l).name.is_null() {
         // fill the table with given functions
         l = l.offset(1);
         lua_pushstring(L, (*l).name);
@@ -786,13 +821,25 @@ pub unsafe fn luaL_requiref(
         lua_pop(L, 1);
         lua_pushcfunction(L, openf);
         lua_pushstring(L, modname);
-        lua_call(L, 1, 1);
-        lua_pushvalue(L, -1);
-        lua_setfield(L, -3, modname);
+        #[cfg(any(feature = "lua52", feature = "lua51"))]
+        {
+            lua_call(L, 1, 1);
+            lua_pushvalue(L, -1);
+            lua_setfield(L, -3, modname);
+        }
+        #[cfg(feature = "luajit")]
+        {
+            lua_call(L, 1, 0);
+            lua_getfield(L, -1, modname);
+        }
     }
-    if glb != 0 {
+    if cfg!(any(feature = "lua52", feature = "lua51")) && glb != 0 {
         lua_pushvalue(L, -1);
         lua_setglobal(L, modname);
     }
+    if cfg!(feature = "luajit") && glb == 0 {
+        lua_pushnil(L);
+        lua_setglobal(L, modname);
+    }
     lua_replace(L, -2);
 }

src/ffi/glue/glue.c

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 // Copyright (c) 2014 J.C. Moyer
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -53,7 +53,7 @@ typedef struct rs_item {
 #define RS_INT(name, val)                                                      \
   { TY_INT, name, .int_val = val }
 
-#if LUA_VERSION_NUM == 503
+#if LUA_VERSION_NUM >= 503
 #define TY_LUAINT 1
 #define RS_LUAINT(name, val)                                                   \
   { TY_LUAINT, name, .lua_int_val = val }
@@ -84,6 +84,8 @@ const char *rs_int_type(int width) {
     return "i32";
   case 8:
     return "i64";
+  case 16:
+    return "i128";
   }
 }
 
@@ -96,6 +98,8 @@ const char *rs_uint_type(int width) {
     return "u32";
   case 8:
     return "u64";
+  case 16:
+    return "u128";
   }
 }
 
@@ -139,7 +143,7 @@ int write_int_item(FILE *f, const char *name, int value) {
   return fprintf(f, "pub const %s: c_int = %d;\n", name, value);
 }
 
-#if LUA_VERSION_NUM == 503
+#if LUA_VERSION_NUM >= 503
 int write_lua_int_item(FILE *f, const char *name, LUA_INTEGER value) {
   return fprintf(f, "pub const %s: LUA_INTEGER = " LUA_INTEGER_FMT ";\n", name,
                  value);
@@ -152,7 +156,7 @@ int write_str_item(FILE *f, const char *name, const char *value) {
   char *buf = malloc(bufsz);
   int ret;
   escape(value, buf, bufsz);
-  ret = fprintf(f, "pub const %s: &'static str = \"%s\";\n", name, buf);
+  ret = fprintf(f, "pub const %s: &str = \"%s\";\n", name, buf);
   free(buf);
   return ret;
 }
@@ -171,7 +175,7 @@ int write_item(FILE *f, const rs_item *c) {
   switch (c->type) {
   case TY_INT:
     return write_int_item(f, c->name, c->int_val);
-#if LUA_VERSION_NUM == 503
+#if LUA_VERSION_NUM >= 503
   case TY_LUAINT:
     return write_lua_int_item(f, c->name, c->lua_int_val);
 #endif
@@ -221,12 +225,8 @@ int main(int argc, const char **argv) {
       // == luaconf.h ==========================================================
 
       RS_COMMENT("luaconf.h"),
-      RS_STR("LUA_PATH_DEFAULT", LUA_PATH_DEFAULT),
-      RS_STR("LUA_CPATH_DEFAULT", LUA_CPATH_DEFAULT),
-      RS_STR("LUA_DIRSEP", LUA_DIRSEP),
       RS_INT("LUA_EXTRASPACE", LUA_EXTRASPACE),
       RS_INT("LUA_IDSIZE", LUA_IDSIZE),
-      RS_INT("LUAL_BUFFERSIZE", LUAL_BUFFERSIZE),
       RS_TYPE("LUA_NUMBER",
               sizeof(LUA_NUMBER) > sizeof(float) ? "c_double" : "c_float"),
       RS_TYPE("LUA_INTEGER", rs_int_type(sizeof(LUA_INTEGER))),
@@ -240,8 +240,6 @@ int main(int argc, const char **argv) {
 
       RS_COMMENT("lua.h"),
       RS_INT("LUA_VERSION_NUM", LUA_VERSION_NUM),
-      RS_STR("LUA_VERSION", LUA_VERSION),
-      RS_STR("LUA_RELEASE", LUA_RELEASE),
       RS_INT("LUA_REGISTRYINDEX", LUA_REGISTRYINDEX),
 #if LUA_VERSION_NUM == 501
       RS_INT("LUA_ENVIRONINDEX", LUA_ENVIRONINDEX),
@@ -251,7 +249,7 @@ int main(int argc, const char **argv) {
       // == lauxlib.h ==========================================================
 
       RS_COMMENT("lauxlib.h"),
-#if LUA_VERSION_NUM == 503
+#if LUA_VERSION_NUM >= 503
       RS_INT("LUAL_NUMSIZES", LUAL_NUMSIZES),
 #endif
 

src/ffi/lauxlib.rs

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 // Copyright (c) 2014 J.C. Moyer
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -28,7 +28,7 @@ use std::ptr;
 
 use super::lua::{self, lua_CFunction, lua_Integer, lua_Number, lua_State};
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use super::glue::LUAL_NUMSIZES;
 
 #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
@@ -49,10 +49,10 @@ pub struct luaL_Reg {
     pub func: lua_CFunction,
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn luaL_checkversion(L: *mut lua_State) {
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     luaL_checkversion_(
         L,
         lua::LUA_VERSION_NUM as lua_Number,
@@ -63,19 +63,19 @@ pub unsafe fn luaL_checkversion(L: *mut lua_State) {
 }
 
 extern "C" {
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn luaL_checkversion_(L: *mut lua_State, ver: lua_Number, sz: usize);
     #[cfg(feature = "lua52")]
     pub fn luaL_checkversion_(L: *mut lua_State, ver: lua_Number);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn luaL_getmetafield(L: *mut lua_State, obj: c_int, e: *const c_char) -> c_int;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "luaL_getmetafield"]
     pub fn luaL_getmetafield_old(L: *mut lua_State, obj: c_int, e: *const c_char) -> c_int;
 
     pub fn luaL_callmeta(L: *mut lua_State, obj: c_int, e: *const c_char) -> c_int;
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn luaL_tolstring(L: *mut lua_State, idx: c_int, len: *mut usize) -> *const c_char;
     pub fn luaL_argerror(L: *mut lua_State, arg: c_int, l: *const c_char) -> c_int;
     pub fn luaL_checklstring(L: *mut lua_State, arg: c_int, l: *mut usize) -> *const c_char;
@@ -90,20 +90,20 @@ extern "C" {
     pub fn luaL_checkinteger(L: *mut lua_State, arg: c_int) -> lua_Integer;
     pub fn luaL_optinteger(L: *mut lua_State, arg: c_int, def: lua_Integer) -> lua_Integer;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_checkstack(L: *mut lua_State, sz: c_int, msg: *const c_char);
     pub fn luaL_checktype(L: *mut lua_State, arg: c_int, t: c_int);
     pub fn luaL_checkany(L: *mut lua_State, arg: c_int);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn luaL_newmetatable(L: *mut lua_State, tname: *const c_char) -> c_int;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "luaL_newmetatable"]
     pub fn luaL_newmetatable_old(L: *mut lua_State, tname: *const c_char) -> c_int;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_setmetatable(L: *mut lua_State, tname: *const c_char);
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_testudata(L: *mut lua_State, ud: c_int, tname: *const c_char) -> *mut c_void;
     pub fn luaL_checkudata(L: *mut lua_State, ud: c_int, tname: *const c_char) -> *mut c_void;
 
@@ -118,9 +118,9 @@ extern "C" {
         lst: *const *const c_char,
     ) -> c_int;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_fileresult(L: *mut lua_State, stat: c_int, fname: *const c_char) -> c_int;
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_execresult(L: *mut lua_State, stat: c_int) -> c_int;
 }
 
@@ -132,21 +132,21 @@ extern "C" {
     pub fn luaL_ref(L: *mut lua_State, t: c_int) -> c_int;
     pub fn luaL_unref(L: *mut lua_State, t: c_int, r: c_int);
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_loadfilex(L: *mut lua_State, filename: *const c_char, mode: *const c_char)
         -> c_int;
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn luaL_loadfile(L: *mut lua_State, filename: *const c_char) -> c_int;
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn luaL_loadfile(L: *mut lua_State, f: *const c_char) -> c_int {
     luaL_loadfilex(L, f, ptr::null())
 }
 
 extern "C" {
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_loadbufferx(
         L: *mut lua_State,
         buff: *const c_char,
@@ -165,9 +165,11 @@ extern "C" {
 
     pub fn luaL_newstate() -> *mut lua_State;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_len(L: *mut lua_State, idx: c_int) -> lua_Integer;
 
+    // TODO (lua54): luaL_addgsub
+
     pub fn luaL_gsub(
         L: *mut lua_State,
         s: *const c_char,
@@ -175,17 +177,17 @@ extern "C" {
         r: *const c_char,
     ) -> *const c_char;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_setfuncs(L: *mut lua_State, l: *const luaL_Reg, nup: c_int);
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_getsubtable(L: *mut lua_State, idx: c_int, fname: *const c_char) -> c_int;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaL_traceback(L: *mut lua_State, L1: *mut lua_State, msg: *const c_char, level: c_int);
 
     // Skip Lua 5.2 implementation in favor of the compat53 one
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn luaL_requiref(
         L: *mut lua_State,
         modname: *const c_char,
@@ -288,7 +290,7 @@ pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) {
 
 // luaL_opt would be implemented here but it is undocumented, so it's omitted
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn luaL_loadbuffer(
     L: *mut lua_State,
@@ -301,4 +303,4 @@ pub unsafe fn luaL_loadbuffer(
 
 // TODO: Add buffer API
 
-// omitted: old module system compatibility
+// omitted: old module system compatibility (removed in 5.4)

src/ffi/lua.rs

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 // Copyright (c) 2014 J.C. Moyer
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -23,20 +23,23 @@
 
 //! Contains definitions from `lua.h`.
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 use std::os::raw::c_uchar;
 use std::os::raw::{c_char, c_int, c_void};
+#[cfg(feature = "lua54")]
+use std::os::raw::{c_uint, c_ushort};
 use std::ptr;
 
 use super::luaconf;
 
-pub use super::glue::{LUA_RELEASE, LUA_VERSION, LUA_VERSION_NUM};
-
-pub use super::glue::LUA_REGISTRYINDEX;
 #[cfg(any(feature = "lua51", feature = "luajit"))]
 pub use super::glue::{LUA_ENVIRONINDEX, LUA_GLOBALSINDEX};
+pub use super::glue::{LUA_REGISTRYINDEX, LUA_VERSION_NUM};
 
-pub const LUA_SIGNATURE: &'static [u8] = b"\x1bLua";
+#[cfg(not(feature = "luajit"))]
+pub const LUA_SIGNATURE: &[u8] = b"\x1bLua";
+#[cfg(feature = "luajit")]
+pub const LUA_SIGNATURE: &[u8] = b"\x1bLJ";
 
 // option for multiple returns in 'lua_pcall' and 'lua_call'
 pub const LUA_MULTRET: c_int = -1;
@@ -51,13 +54,14 @@ pub use super::compat53::{
 #[cfg(any(feature = "lua51", feature = "luajit"))]
 pub use super::compat53::{
     lua_absindex, lua_arith, lua_compare, lua_copy, lua_len, lua_pushglobaltable, lua_pushstring,
-    lua_rawlen, lua_rawsetp, lua_resume, lua_setuservalue, lua_tonumberx, lua_upvalueindex,
+    lua_rawlen, lua_rawsetp, lua_resume as lua_resume_53, lua_setuservalue, lua_tonumberx,
+    lua_upvalueindex,
 };
 
 #[cfg(feature = "lua52")]
 pub use super::compat53::lua_getglobal;
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub fn lua_upvalueindex(i: c_int) -> c_int {
     LUA_REGISTRYINDEX - i
@@ -71,7 +75,7 @@ pub const LUA_ERRSYNTAX: c_int = 3;
 pub const LUA_ERRMEM: c_int = 4;
 #[cfg(any(feature = "lua53", feature = "lua52"))]
 pub const LUA_ERRGCMM: c_int = 5;
-#[cfg(any(feature = "lua51", feature = "luajit"))]
+#[cfg(any(feature = "lua54", feature = "lua51", feature = "luajit"))]
 pub const LUA_ERRERR: c_int = 5;
 #[cfg(any(feature = "lua53", feature = "lua52"))]
 pub const LUA_ERRERR: c_int = 6;
@@ -91,6 +95,8 @@ pub const LUA_TFUNCTION: c_int = 6;
 pub const LUA_TUSERDATA: c_int = 7;
 pub const LUA_TTHREAD: c_int = 8;
 
+#[cfg(feature = "lua54")]
+pub const LUA_NUMTYPES: c_int = 9;
 #[cfg(any(feature = "lua53", feature = "lua52"))]
 pub const LUA_NUMTAGS: c_int = 9;
 
@@ -98,11 +104,11 @@ pub const LUA_NUMTAGS: c_int = 9;
 pub const LUA_MINSTACK: c_int = 20;
 
 // predefined values in the registry
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub const LUA_RIDX_MAINTHREAD: lua_Integer = 1;
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub const LUA_RIDX_GLOBALS: lua_Integer = 2;
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub const LUA_RIDX_LAST: lua_Integer = LUA_RIDX_GLOBALS;
 
 /// A Lua number, usually equivalent to `f64`.
@@ -115,14 +121,14 @@ pub type lua_Integer = luaconf::LUA_INTEGER;
 pub type lua_Unsigned = luaconf::LUA_UNSIGNED;
 
 // type for continuation-function contexts
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub type lua_KContext = luaconf::LUA_KCONTEXT;
 
 /// Type for native functions that can be passed to Lua.
 pub type lua_CFunction = unsafe extern "C" fn(L: *mut lua_State) -> c_int;
 
 // Type for continuation functions
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub type lua_KFunction =
     unsafe extern "C" fn(L: *mut lua_State, status: c_int, ctx: lua_KContext) -> c_int;
 
@@ -132,7 +138,7 @@ pub type lua_Reader =
 pub type lua_Writer =
     unsafe extern "C" fn(L: *mut lua_State, p: *const c_void, sz: usize, ud: *mut c_void) -> c_int;
 
-/// Type for memory-allocation functions.
+// Type for memory-allocation functions.
 pub type lua_Alloc = unsafe extern "C" fn(
     ud: *mut c_void,
     ptr: *mut c_void,
@@ -140,19 +146,28 @@ pub type lua_Alloc = unsafe extern "C" fn(
     nsize: usize,
 ) -> *mut c_void;
 
+// Type for warning functions
+#[cfg(feature = "lua54")]
+pub type lua_WarnFunction =
+    unsafe extern "C" fn(ud: *mut c_void, msg: *const c_char, tocont: c_int);
+
 extern "C" {
     // state manipulation
     pub fn lua_newstate(f: lua_Alloc, ud: *mut c_void) -> *mut lua_State;
     pub fn lua_close(L: *mut lua_State);
     pub fn lua_newthread(L: *mut lua_State) -> *mut lua_State;
+    #[cfg(feature = "lua54")]
+    pub fn lua_resetthread(L: *mut lua_State) -> c_int;
 
     pub fn lua_atpanic(L: *mut lua_State, panicf: lua_CFunction) -> lua_CFunction;
 
+    #[cfg(feature = "lua54")]
+    pub fn lua_version(L: *mut lua_State) -> lua_Number;
     #[cfg(feature = "lua53")]
     pub fn lua_version(L: *mut lua_State) -> *const lua_Number;
 
     // basic stack manipulation
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_absindex(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_gettop(L: *mut lua_State) -> c_int;
     pub fn lua_settop(L: *mut lua_State, idx: c_int);
@@ -163,9 +178,9 @@ extern "C" {
     pub fn lua_insert(L: *mut lua_State, idx: c_int);
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     pub fn lua_replace(L: *mut lua_State, idx: c_int);
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_rotate(L: *mut lua_State, idx: c_int, n: c_int);
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_copy(L: *mut lua_State, fromidx: c_int, toidx: c_int);
     pub fn lua_checkstack(L: *mut lua_State, sz: c_int) -> c_int;
 
@@ -175,7 +190,7 @@ extern "C" {
     pub fn lua_isnumber(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_isstring(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_iscfunction(L: *mut lua_State, idx: c_int) -> c_int;
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_isinteger(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_isuserdata(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_type(L: *mut lua_State, idx: c_int) -> c_int;
@@ -183,17 +198,17 @@ extern "C" {
 
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn lua_tonumber(L: *mut lua_State, idx: c_int) -> lua_Number;
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_tonumberx(L: *mut lua_State, idx: c_int, isnum: *mut c_int) -> lua_Number;
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn lua_tointeger(L: *mut lua_State, idx: c_int) -> lua_Integer;
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_tointegerx(L: *mut lua_State, idx: c_int, isnum: *mut c_int) -> lua_Integer;
     pub fn lua_toboolean(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_tolstring(L: *mut lua_State, idx: c_int, len: *mut usize) -> *const c_char;
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn lua_objlen(L: *mut lua_State, idx: c_int) -> usize;
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_rawlen(L: *mut lua_State, idx: c_int) -> usize;
     pub fn lua_tocfunction(L: *mut lua_State, idx: c_int) -> lua_CFunction;
     pub fn lua_touserdata(L: *mut lua_State, idx: c_int) -> *mut c_void;
@@ -215,31 +230,31 @@ pub const LUA_OPPOW: c_int = 5;
 #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
 pub const LUA_OPUNM: c_int = 6;
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPMOD: c_int = 3;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPPOW: c_int = 4;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPDIV: c_int = 5;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPIDIV: c_int = 6;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPBAND: c_int = 7;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPBOR: c_int = 8;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPBXOR: c_int = 9;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPSHL: c_int = 10;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPSHR: c_int = 11;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPUNM: c_int = 12;
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub const LUA_OPBNOT: c_int = 13;
 
 extern "C" {
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_arith(L: *mut lua_State, op: c_int);
 }
 
@@ -253,7 +268,7 @@ extern "C" {
     pub fn lua_rawequal(L: *mut lua_State, idx1: c_int, idx2: c_int) -> c_int;
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn lua_lessthan(L: *mut lua_State, idx1: c_int, idx2: c_int) -> c_int;
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_compare(L: *mut lua_State, idx1: c_int, idx2: c_int, op: c_int) -> c_int;
 }
 
@@ -263,13 +278,13 @@ extern "C" {
     pub fn lua_pushnumber(L: *mut lua_State, n: lua_Number);
     pub fn lua_pushinteger(L: *mut lua_State, n: lua_Integer);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_pushlstring(L: *mut lua_State, s: *const c_char, l: usize) -> *const c_char;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_pushlstring"]
     pub fn lua_pushlstring_old(L: *mut lua_State, s: *const c_char, l: usize) -> *const c_char;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_pushstring(L: *mut lua_State, s: *const c_char) -> *const c_char;
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_pushstring"]
@@ -286,49 +301,59 @@ extern "C" {
 
 // get functions (Lua -> stack)
 extern "C" {
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_getglobal(L: *mut lua_State, var: *const c_char) -> c_int;
     #[cfg(feature = "lua52")]
     #[link_name = "lua_getglobal"]
     pub fn lua_getglobal_old(L: *mut lua_State, var: *const c_char);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_gettable(L: *mut lua_State, idx: c_int) -> c_int;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_gettable"]
     pub fn lua_gettable_old(L: *mut lua_State, idx: c_int);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_getfield(L: *mut lua_State, idx: c_int, k: *const c_char) -> c_int;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_getfield"]
     pub fn lua_getfield_old(L: *mut lua_State, idx: c_int, k: *const c_char);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_geti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_int;
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_rawget(L: *mut lua_State, idx: c_int) -> c_int;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_rawget"]
     pub fn lua_rawget_old(L: *mut lua_State, idx: c_int);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_rawgeti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_int;
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_rawgeti"]
     pub fn lua_rawgeti_old(L: *mut lua_State, idx: c_int, n: lua_Integer);
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_rawgetp(L: *mut lua_State, idx: c_int, p: *const c_void) -> c_int;
     #[cfg(feature = "lua52")]
     #[link_name = "lua_rawgetp"]
     pub fn lua_rawgetp_old(L: *mut lua_State, idx: c_int, p: *const c_void);
 
     pub fn lua_createtable(L: *mut lua_State, narr: c_int, nrec: c_int);
+    #[cfg(feature = "lua54")]
+    pub fn lua_newuserdatauv(L: *mut lua_State, sz: usize, nuvalue: c_int) -> *mut c_void;
+    #[cfg(any(
+        feature = "lua53",
+        feature = "lua52",
+        feature = "lua51",
+        feature = "luajit"
+    ))]
     pub fn lua_newuserdata(L: *mut lua_State, sz: usize) -> *mut c_void;
     pub fn lua_getmetatable(L: *mut lua_State, objindex: c_int) -> c_int;
 
+    #[cfg(feature = "lua54")]
+    pub fn lua_getiuservalue(L: *mut lua_State, idx: c_int, n: c_int) -> c_int;
     #[cfg(feature = "lua53")]
     pub fn lua_getuservalue(L: *mut lua_State, idx: c_int) -> c_int;
     #[cfg(feature = "lua52")]
@@ -338,28 +363,48 @@ extern "C" {
     pub fn lua_getfenv(L: *mut lua_State, idx: c_int);
 }
 
+#[cfg(feature = "lua54")]
+#[inline(always)]
+pub unsafe fn lua_newuserdata(L: *mut lua_State, sz: usize) -> *mut c_void {
+    lua_newuserdatauv(L, sz, 1)
+}
+
+#[cfg(feature = "lua54")]
+#[inline(always)]
+pub unsafe fn lua_getuservalue(L: *mut lua_State, idx: c_int) -> c_int {
+    lua_getiuservalue(L, idx, 1)
+}
+
 // set functions (stack -> Lua)
 extern "C" {
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_setglobal(L: *mut lua_State, var: *const c_char);
     pub fn lua_settable(L: *mut lua_State, idx: c_int);
     pub fn lua_setfield(L: *mut lua_State, idx: c_int, k: *const c_char);
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_seti(L: *mut lua_State, idx: c_int, n: lua_Integer);
     pub fn lua_rawset(L: *mut lua_State, idx: c_int);
     pub fn lua_rawseti(L: *mut lua_State, idx: c_int, n: lua_Integer);
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_rawsetp(L: *mut lua_State, idx: c_int, p: *const c_void);
     pub fn lua_setmetatable(L: *mut lua_State, objindex: c_int) -> c_int;
+    #[cfg(feature = "lua54")]
+    pub fn lua_setiuservalue(L: *mut lua_State, idx: c_int, n: c_int) -> c_int;
     #[cfg(any(feature = "lua53", feature = "lua52"))]
     pub fn lua_setuservalue(L: *mut lua_State, idx: c_int);
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn lua_setfenv(L: *mut lua_State, idx: c_int) -> c_int;
 }
 
+#[cfg(feature = "lua54")]
+#[inline(always)]
+pub unsafe fn lua_setuservalue(L: *mut lua_State, idx: c_int) {
+    lua_setiuservalue(L, idx, 1);
+}
+
 // 'load' and 'call' functions (load and run Lua code)
 extern "C" {
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_callk(
         L: *mut lua_State,
         nargs: c_int,
@@ -376,7 +421,7 @@ extern "C" {
         k: Option<lua_CFunction>,
     );
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_pcallk(
         L: *mut lua_State,
         nargs: c_int,
@@ -412,7 +457,7 @@ extern "C" {
         mode: *const c_char,
     ) -> c_int;
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_dump(
         L: *mut lua_State,
         writer: lua_Writer,
@@ -424,13 +469,13 @@ extern "C" {
     pub fn lua_dump_old(L: *mut lua_State, writer: lua_Writer, data: *mut c_void) -> c_int;
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn lua_call(L: *mut lua_State, n: c_int, r: c_int) {
     lua_callk(L, n, r, 0, None)
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn lua_pcall(L: *mut lua_State, n: c_int, r: c_int, f: c_int) -> c_int {
     lua_pcallk(L, n, r, f, 0, None)
@@ -438,7 +483,7 @@ pub unsafe fn lua_pcall(L: *mut lua_State, n: c_int, r: c_int, f: c_int) -> c_in
 
 // coroutine functions
 extern "C" {
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_yieldk(
         L: *mut lua_State,
         nresults: c_int,
@@ -455,23 +500,58 @@ extern "C" {
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     pub fn lua_yield(L: *mut lua_State, nresults: c_int) -> c_int;
 
+    #[cfg(feature = "lua54")]
+    pub fn lua_resume(
+        L: *mut lua_State,
+        from: *mut lua_State,
+        narg: c_int,
+        nres: *mut c_int,
+    ) -> c_int;
     #[cfg(any(feature = "lua53", feature = "lua52"))]
-    pub fn lua_resume(L: *mut lua_State, from: *mut lua_State, narg: c_int) -> c_int;
+    #[link_name = "lua_resume"]
+    pub fn lua_resume_53(L: *mut lua_State, from: *mut lua_State, narg: c_int) -> c_int;
     #[cfg(any(feature = "lua51", feature = "luajit"))]
     #[link_name = "lua_resume"]
     pub fn lua_resume_old(L: *mut lua_State, narg: c_int) -> c_int;
 
     pub fn lua_status(L: *mut lua_State) -> c_int;
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_isyieldable(L: *mut lua_State) -> c_int;
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn lua_yield(L: *mut lua_State, n: c_int) -> c_int {
     lua_yieldk(L, n, 0, None)
 }
 
+#[cfg(any(
+    feature = "lua53",
+    feature = "lua52",
+    feature = "lua51",
+    feature = "luajit"
+))]
+#[inline(always)]
+pub unsafe fn lua_resume(
+    L: *mut lua_State,
+    from: *mut lua_State,
+    narg: c_int,
+    nres: *mut c_int,
+) -> c_int {
+    let ret = lua_resume_53(L, from, narg);
+    if ret == LUA_OK || ret == LUA_YIELD {
+        *nres = lua_gettop(L);
+    }
+    ret
+}
+
+// warning-related functions
+#[cfg(feature = "lua54")]
+extern "C" {
+    pub fn lua_setwarnf(L: *mut lua_State, f: lua_WarnFunction, ud: *mut c_void);
+    pub fn lua_warning(L: *mut lua_State, msg: *const c_char, tocont: c_int);
+}
+
 // garbage-collection function and options
 pub const LUA_GCSTOP: c_int = 0;
 pub const LUA_GCRESTART: c_int = 1;
@@ -481,10 +561,22 @@ pub const LUA_GCCOUNTB: c_int = 4;
 pub const LUA_GCSTEP: c_int = 5;
 pub const LUA_GCSETPAUSE: c_int = 6;
 pub const LUA_GCSETSTEPMUL: c_int = 7;
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub const LUA_GCISRUNNING: c_int = 9;
+#[cfg(feature = "lua54")]
+pub const LUA_GCGEN: c_int = 10;
+#[cfg(feature = "lua54")]
+pub const LUA_GCINC: c_int = 11;
 
 extern "C" {
+    #[cfg(feature = "lua54")]
+    pub fn lua_gc(L: *mut lua_State, what: c_int, ...) -> c_int;
+    #[cfg(any(
+        feature = "lua53",
+        feature = "lua52",
+        feature = "lua51",
+        feature = "luajit"
+    ))]
     pub fn lua_gc(L: *mut lua_State, what: c_int, data: c_int) -> c_int;
 }
 
@@ -493,29 +585,31 @@ extern "C" {
     pub fn lua_error(L: *mut lua_State) -> !;
     pub fn lua_next(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_concat(L: *mut lua_State, n: c_int);
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_len(L: *mut lua_State, idx: c_int);
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn lua_stringtonumber(L: *mut lua_State, s: *const c_char) -> usize;
     pub fn lua_getallocf(L: *mut lua_State, ud: *mut *mut c_void) -> lua_Alloc;
     pub fn lua_setallocf(L: *mut lua_State, f: lua_Alloc, ud: *mut c_void);
+    #[cfg(feature = "lua54")]
+    pub fn lua_toclose(L: *mut lua_State, idx: c_int);
 }
 
 // some useful macros
 // here, implemented as Rust functions
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 #[inline(always)]
 pub unsafe fn lua_getextraspace(L: *mut lua_State) -> *mut c_void {
     L.offset(-super::glue::LUA_EXTRASPACE as isize) as *mut c_void
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn lua_tonumber(L: *mut lua_State, i: c_int) -> lua_Number {
     lua_tonumberx(L, i, ptr::null_mut())
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn lua_tointeger(L: *mut lua_State, i: c_int) -> lua_Integer {
     lua_tointegerx(L, i, ptr::null_mut())
@@ -601,7 +695,7 @@ pub unsafe fn lua_getglobal(L: *mut lua_State, var: *const c_char) -> c_int {
     lua_getfield(L, LUA_GLOBALSINDEX, var)
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[inline(always)]
 pub unsafe fn lua_pushglobaltable(L: *mut lua_State) -> c_int {
     lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_GLOBALS)
@@ -612,20 +706,20 @@ pub unsafe fn lua_tostring(L: *mut lua_State, i: c_int) -> *const c_char {
     lua_tolstring(L, i, ptr::null_mut())
 }
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 #[inline(always)]
 pub unsafe fn lua_insert(L: *mut lua_State, idx: c_int) {
     lua_rotate(L, idx, 1)
 }
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 #[inline(always)]
 pub unsafe fn lua_remove(L: *mut lua_State, idx: c_int) {
     lua_rotate(L, idx, -1);
     lua_pop(L, 1)
 }
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 #[inline(always)]
 pub unsafe fn lua_replace(L: *mut lua_State, idx: c_int) {
     lua_copy(L, -1, idx);
@@ -647,7 +741,7 @@ pub const LUA_MASKLINE: c_int = 1 << (LUA_HOOKLINE as usize);
 pub const LUA_MASKCOUNT: c_int = 1 << (LUA_HOOKCOUNT as usize);
 
 /// Type for functions to be called on debug events.
-pub type lua_Hook = extern "C" fn(L: *mut lua_State, ar: *mut lua_Debug);
+pub type lua_Hook = unsafe extern "C" fn(L: *mut lua_State, ar: *mut lua_Debug);
 
 extern "C" {
     pub fn lua_getstack(L: *mut lua_State, level: c_int, ar: *mut lua_Debug) -> c_int;
@@ -657,18 +751,21 @@ extern "C" {
     pub fn lua_getupvalue(L: *mut lua_State, funcindex: c_int, n: c_int) -> *const c_char;
     pub fn lua_setupvalue(L: *mut lua_State, funcindex: c_int, n: c_int) -> *const c_char;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_upvalueid(L: *mut lua_State, fidx: c_int, n: c_int) -> *mut c_void;
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn lua_upvaluejoin(L: *mut lua_State, fidx1: c_int, n1: c_int, fidx2: c_int, n2: c_int);
 
-    pub fn lua_sethook(L: *mut lua_State, func: lua_Hook, mask: c_int, count: c_int);
+    pub fn lua_sethook(L: *mut lua_State, func: Option<lua_Hook>, mask: c_int, count: c_int);
     pub fn lua_gethook(L: *mut lua_State) -> Option<lua_Hook>;
     pub fn lua_gethookmask(L: *mut lua_State) -> c_int;
     pub fn lua_gethookcount(L: *mut lua_State) -> c_int;
+
+    #[cfg(feature = "lua54")]
+    pub fn lua_setcstacklimit(L: *mut lua_State, limit: c_uint) -> c_int;
 }
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[repr(C)]
 pub struct lua_Debug {
     pub event: c_int,
@@ -676,6 +773,8 @@ pub struct lua_Debug {
     pub namewhat: *const c_char,
     pub what: *const c_char,
     pub source: *const c_char,
+    #[cfg(feature = "lua54")]
+    pub srclen: usize,
     pub currentline: c_int,
     pub linedefined: c_int,
     pub lastlinedefined: c_int,
@@ -683,6 +782,10 @@ pub struct lua_Debug {
     pub nparams: c_uchar,
     pub isvararg: c_char,
     pub istailcall: c_char,
+    #[cfg(feature = "lua54")]
+    pub ftransfer: c_ushort,
+    #[cfg(feature = "lua54")]
+    pub ntransfer: c_ushort,
     pub short_src: [c_char; luaconf::LUA_IDSIZE as usize],
     // lua.h mentions this is for private use
     i_ci: *mut c_void,

src/ffi/luaconf.rs

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 // Copyright (c) 2014 J.C. Moyer
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -23,15 +23,14 @@
 
 //! Contains definitions from `luaconf.h`.
 
-pub use super::glue::LUAL_BUFFERSIZE;
 pub use super::glue::LUA_INTEGER;
 pub use super::glue::LUA_NUMBER;
 pub use super::glue::LUA_UNSIGNED;
 
 pub use super::glue::LUA_IDSIZE;
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use super::glue::LUAL_NUMSIZES;
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub type LUA_KCONTEXT = isize; // intptr_t

src/ffi/lualib.rs

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 // Copyright (c) 2014 J.C. Moyer
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -32,7 +32,7 @@ pub use super::glue::{
     LUA_STRLIBNAME, LUA_TABLIBNAME,
 };
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use super::glue::LUA_UTF8LIBNAME;
 
 #[cfg(any(feature = "lua52", feature = "luajit"))]
@@ -43,13 +43,13 @@ pub use super::glue::{LUA_FFILIBNAME, LUA_JITLIBNAME};
 
 extern "C" {
     pub fn luaopen_base(L: *mut lua_State) -> c_int;
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     pub fn luaopen_coroutine(L: *mut lua_State) -> c_int;
     pub fn luaopen_table(L: *mut lua_State) -> c_int;
     pub fn luaopen_io(L: *mut lua_State) -> c_int;
     pub fn luaopen_os(L: *mut lua_State) -> c_int;
     pub fn luaopen_string(L: *mut lua_State) -> c_int;
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     pub fn luaopen_utf8(L: *mut lua_State) -> c_int;
     #[cfg(feature = "lua52")]
     pub fn luaopen_bit32(L: *mut lua_State) -> c_int;

src/ffi/mod.rs

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2019 A. Orlenko
+// Copyright (c) 2019-2021 A. Orlenko
 // Copyright (c) 2014 J.C. Moyer
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -36,11 +36,14 @@ pub use self::lua::{
     lua_Unsigned, lua_Writer,
 };
 
-#[cfg(feature = "lua53")]
+#[cfg(feature = "lua54")]
+pub use self::lua::lua_WarnFunction;
+
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use self::lua::{lua_KContext, lua_KFunction};
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
-pub use self::lua::lua_setfenv;
+pub use self::lua::{lua_getfenv, lua_setfenv};
 
 // C API functions
 pub use self::lua::{
@@ -155,10 +158,16 @@ pub use self::lua::{
     lua_yield,
 };
 
-#[cfg(feature = "lua53")]
+#[cfg(feature = "lua54")]
+pub use self::lua::{
+    lua_getiuservalue, lua_newuserdatauv, lua_resetthread, lua_setcstacklimit, lua_setiuservalue,
+    lua_setwarnf, lua_toclose, lua_warning,
+};
+
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use self::lua::{lua_isyieldable, lua_version};
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub use self::lua::{lua_callk, lua_pcallk, lua_upvalueid, lua_upvaluejoin, lua_yieldk};
 
 // auxiliary library types
@@ -177,7 +186,7 @@ pub use self::lauxlib::{
     luaL_where,
 };
 
-#[cfg(any(feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub use self::lauxlib::{luaL_execresult, luaL_fileresult, luaL_loadfilex};
 
 // lualib.h functions
@@ -186,7 +195,7 @@ pub use self::lualib::{
     luaopen_package, luaopen_string, luaopen_table,
 };
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use self::lualib::{luaopen_coroutine, luaopen_utf8};
 
 #[cfg(feature = "lua52")]
@@ -202,17 +211,23 @@ pub use self::lua::{
     LUA_HOOKCOUNT, LUA_HOOKLINE, LUA_HOOKRET, LUA_HOOKTAILCALL, LUA_MASKCALL, LUA_MASKCOUNT,
     LUA_MASKLINE, LUA_MASKRET, LUA_MINSTACK, LUA_MULTRET, LUA_OK, LUA_OPADD, LUA_OPDIV, LUA_OPEQ,
     LUA_OPLE, LUA_OPLT, LUA_OPMOD, LUA_OPMUL, LUA_OPPOW, LUA_OPSUB, LUA_OPUNM, LUA_REGISTRYINDEX,
-    LUA_TBOOLEAN, LUA_TFUNCTION, LUA_TLIGHTUSERDATA, LUA_TNIL, LUA_TNONE, LUA_TNUMBER, LUA_TSTRING,
-    LUA_TTABLE, LUA_TTHREAD, LUA_TUSERDATA, LUA_YIELD,
+    LUA_SIGNATURE, LUA_TBOOLEAN, LUA_TFUNCTION, LUA_TLIGHTUSERDATA, LUA_TNIL, LUA_TNONE,
+    LUA_TNUMBER, LUA_TSTRING, LUA_TTABLE, LUA_TTHREAD, LUA_TUSERDATA, LUA_YIELD,
 };
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use self::lua::{
     LUA_OPBAND, LUA_OPBNOT, LUA_OPBOR, LUA_OPBXOR, LUA_OPIDIV, LUA_OPSHL, LUA_OPSHR,
 };
 
+#[cfg(feature = "lua54")]
+pub use self::lua::{LUA_GCGEN, LUA_GCINC};
+
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+pub use self::lua::{LUA_GCISRUNNING, LUA_RIDX_GLOBALS, LUA_RIDX_MAINTHREAD};
+
 #[cfg(any(feature = "lua53", feature = "lua52"))]
-pub use self::lua::{LUA_ERRGCMM, LUA_GCISRUNNING, LUA_RIDX_GLOBALS, LUA_RIDX_MAINTHREAD};
+pub use self::lua::LUA_ERRGCMM;
 
 #[cfg(any(feature = "lua51", feature = "luajit"))]
 pub use self::lua::{LUA_ENVIRONINDEX, LUA_GLOBALSINDEX};
@@ -226,7 +241,7 @@ pub use self::lualib::{
     LUA_STRLIBNAME, LUA_TABLIBNAME,
 };
 
-#[cfg(feature = "lua53")]
+#[cfg(any(feature = "lua54", feature = "lua53"))]
 pub use self::lualib::LUA_UTF8LIBNAME;
 
 #[cfg(any(feature = "lua52", feature = "luajit"))]
@@ -238,7 +253,30 @@ pub use self::lualib::{LUA_FFILIBNAME, LUA_JITLIBNAME};
 // Not actually defined in lua.h / luaconf.h
 pub const LUA_MAX_UPVALUES: c_int = 255;
 
+// Copied from https://github.com/rust-lang/rust/blob/master/src/libstd/sys_common/alloc.rs
+#[cfg(all(any(
+    target_arch = "x86",
+    target_arch = "arm",
+    target_arch = "mips",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "asmjs",
+    target_arch = "wasm32",
+    target_arch = "hexagon"
+)))]
+pub const SYS_MIN_ALIGN: usize = 8;
+#[cfg(all(any(
+    target_arch = "x86_64",
+    target_arch = "aarch64",
+    target_arch = "mips64",
+    target_arch = "s390x",
+    target_arch = "sparc64",
+    target_arch = "riscv64"
+)))]
+pub const SYS_MIN_ALIGN: usize = 16;
+
 #[allow(unused_imports, dead_code, non_camel_case_types)]
+#[allow(clippy::unreadable_literal)]
 mod glue {
     include!(concat!(env!("OUT_DIR"), "/glue.rs"));
 }
@@ -250,3 +288,5 @@ mod lauxlib;
 mod lua;
 mod luaconf;
 mod lualib;
+
+pub mod safe;

src/ffi/safe.rs

@@ -0,0 +1,278 @@
+use std::ffi::CString;
+use std::os::raw::{c_char, c_int, c_void};
+
+use crate::error::Result;
+use crate::util::protect_lua;
+
+use super::lua::{lua_CFunction, lua_Debug, lua_Integer, lua_State};
+
+extern "C" {
+    #[link_name = "MLUA_WRAPPED_ERROR_SIZE"]
+    pub static mut WRAPPED_ERROR_SIZE: usize;
+    #[link_name = "MLUA_WRAPPED_PANIC_SIZE"]
+    pub static mut WRAPPED_PANIC_SIZE: usize;
+    #[link_name = "MLUA_WRAPPED_ERROR_KEY"]
+    pub static mut WRAPPED_ERROR_KEY: *const c_void;
+    #[link_name = "MLUA_WRAPPED_PANIC_KEY"]
+    pub static mut WRAPPED_PANIC_KEY: *const c_void;
+
+    pub fn lua_call_mlua_hook_proc(L: *mut lua_State, ar: *mut lua_Debug);
+
+    pub fn meta_index_impl(state: *mut lua_State) -> c_int;
+    pub fn meta_newindex_impl(state: *mut lua_State) -> c_int;
+    pub fn bind_call_impl(state: *mut lua_State) -> c_int;
+    pub fn error_traceback(state: *mut lua_State) -> c_int;
+    pub fn lua_nopanic_pcall(state: *mut lua_State) -> c_int;
+    pub fn lua_nopanic_xpcall(state: *mut lua_State) -> c_int;
+
+    fn lua_gc_s(L: *mut lua_State) -> c_int;
+    fn luaL_ref_s(L: *mut lua_State) -> c_int;
+    fn lua_pushlstring_s(L: *mut lua_State) -> c_int;
+    fn lua_tolstring_s(L: *mut lua_State) -> c_int;
+    fn lua_newthread_s(L: *mut lua_State) -> c_int;
+    fn lua_newuserdata_s(L: *mut lua_State) -> c_int;
+    fn lua_newwrappederror_s(L: *mut lua_State) -> c_int;
+    fn lua_pushcclosure_s(L: *mut lua_State) -> c_int;
+    fn lua_pushrclosure_s(L: *mut lua_State) -> c_int;
+    fn luaL_requiref_s(L: *mut lua_State) -> c_int;
+    fn error_traceback_s(L: *mut lua_State) -> c_int;
+
+    fn lua_newtable_s(L: *mut lua_State) -> c_int;
+    fn lua_createtable_s(L: *mut lua_State) -> c_int;
+    fn lua_gettable_s(L: *mut lua_State) -> c_int;
+    fn lua_settable_s(L: *mut lua_State) -> c_int;
+    fn lua_geti_s(L: *mut lua_State) -> c_int;
+    fn lua_rawset_s(L: *mut lua_State) -> c_int;
+    fn lua_rawseti_s(L: *mut lua_State) -> c_int;
+    fn lua_rawsetp_s(L: *mut lua_State) -> c_int;
+    fn lua_rawsetfield_s(L: *mut lua_State) -> c_int;
+    fn lua_rawinsert_s(L: *mut lua_State) -> c_int;
+    fn lua_rawremove_s(L: *mut lua_State) -> c_int;
+    fn luaL_len_s(L: *mut lua_State) -> c_int;
+    fn lua_next_s(L: *mut lua_State) -> c_int;
+}
+
+#[repr(C)]
+struct StringArg {
+    data: *const c_char,
+    len: usize,
+}
+
+//
+// Common functions
+//
+
+// Uses 4 stack spaces
+pub unsafe fn lua_gc(state: *mut lua_State, what: c_int, data: c_int) -> Result<c_int> {
+    super::lua_pushinteger(state, what as lua_Integer);
+    super::lua_pushinteger(state, data as lua_Integer);
+    protect_lua(state, 2, lua_gc_s)?;
+    let ret = super::lua_tointeger(state, -1) as c_int;
+    super::lua_pop(state, 1);
+    Ok(ret)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn luaL_ref(state: *mut lua_State, table: c_int) -> Result<c_int> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -2, 1);
+    protect_lua(state, 2, luaL_ref_s)?;
+    let ret = super::lua_tointeger(state, -1) as c_int;
+    super::lua_pop(state, 1);
+    Ok(ret)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_pushstring<S: AsRef<[u8]> + ?Sized>(state: *mut lua_State, s: &S) -> Result<()> {
+    let s = s.as_ref();
+    let s = StringArg {
+        data: s.as_ptr() as *const c_char,
+        len: s.len(),
+    };
+    super::lua_pushlightuserdata(state, &s as *const StringArg as *mut c_void);
+    protect_lua(state, 1, lua_pushlstring_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_tolstring(
+    state: *mut lua_State,
+    index: c_int,
+    len: *mut usize,
+) -> Result<*const c_char> {
+    let index = super::lua_absindex(state, index);
+    super::lua_pushvalue(state, index);
+    super::lua_pushlightuserdata(state, len as *mut c_void);
+    protect_lua(state, 2, lua_tolstring_s)?;
+    let s = super::lua_touserdata(state, -1);
+    super::lua_pop(state, 1);
+    super::lua_replace(state, index);
+    Ok(s as *const c_char)
+}
+
+// Uses 2 stack spaces
+pub unsafe fn lua_newthread(state: *mut lua_State) -> Result<*mut lua_State> {
+    protect_lua(state, 0, lua_newthread_s)?;
+    Ok(super::lua_tothread(state, -1))
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_newuserdata(state: *mut lua_State, size: usize) -> Result<*mut c_void> {
+    super::lua_pushinteger(state, size as lua_Integer);
+    protect_lua(state, 1, lua_newuserdata_s)?;
+    Ok(super::lua_touserdata(state, -1))
+}
+
+// Uses 2 stack spaces
+pub unsafe fn lua_newwrappederror(state: *mut lua_State) -> Result<*mut c_void> {
+    protect_lua(state, 0, lua_newwrappederror_s)?;
+    Ok(super::lua_touserdata(state, -1))
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_pushcclosure(state: *mut lua_State, f: lua_CFunction, n: c_int) -> Result<()> {
+    super::lua_pushlightuserdata(state, f as *mut c_void);
+    protect_lua(state, n + 1, lua_pushcclosure_s)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_pushrclosure(state: *mut lua_State, f: lua_CFunction, n: c_int) -> Result<()> {
+    super::lua_pushlightuserdata(state, f as *mut c_void);
+    if n > 0 {
+        super::lua_rotate(state, -n - 1, 1);
+    }
+    protect_lua(state, n + 1, lua_pushrclosure_s)
+}
+
+// Uses 5 stack spaces
+pub unsafe fn luaL_requiref<S: AsRef<[u8]> + ?Sized>(
+    state: *mut lua_State,
+    modname: &S,
+    openf: lua_CFunction,
+    glb: c_int,
+) -> Result<()> {
+    let modname = mlua_expect!(CString::new(modname.as_ref()), "modname contains nil bytes");
+    super::lua_pushlightuserdata(state, modname.as_ptr() as *mut c_void);
+    super::lua_pushlightuserdata(state, openf as *mut c_void);
+    super::lua_pushinteger(state, glb as lua_Integer);
+    protect_lua(state, 3, luaL_requiref_s)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn error_traceback2(state: *mut lua_State, state2: *mut lua_State) -> Result<()> {
+    mlua_assert!(
+        state != state2,
+        "error_traceback2 must be used with two different states"
+    );
+    super::lua_pushlightuserdata(state, state2);
+    protect_lua(state, 1, error_traceback_s)
+}
+
+//
+// Table functions
+//
+
+// Uses 2 stack spaces
+pub unsafe fn lua_newtable(state: *mut lua_State) -> Result<()> {
+    protect_lua(state, 0, lua_newtable_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_createtable(state: *mut lua_State, narr: c_int, nrec: c_int) -> Result<()> {
+    super::lua_pushinteger(state, narr as lua_Integer);
+    super::lua_pushinteger(state, nrec as lua_Integer);
+    protect_lua(state, 2, lua_createtable_s)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_gettable(state: *mut lua_State, table: c_int) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -2, 1);
+    protect_lua(state, 2, lua_gettable_s)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_settable(state: *mut lua_State, table: c_int) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -3, 1);
+    protect_lua(state, 3, lua_settable_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_geti(state: *mut lua_State, table: c_int, i: lua_Integer) -> Result<c_int> {
+    super::lua_pushvalue(state, table);
+    super::lua_pushinteger(state, i);
+    protect_lua(state, 2, lua_geti_s).map(|_| super::lua_type(state, -1))
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_rawset(state: *mut lua_State, table: c_int) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -3, 1);
+    protect_lua(state, 3, lua_rawset_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_rawseti(state: *mut lua_State, table: c_int, i: lua_Integer) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -2, 1);
+    super::lua_pushinteger(state, i);
+    protect_lua(state, 3, lua_rawseti_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_rawsetp(state: *mut lua_State, table: c_int, ptr: *const c_void) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -2, 1);
+    super::lua_pushlightuserdata(state, ptr as *mut c_void);
+    protect_lua(state, 3, lua_rawsetp_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_rawsetfield<S>(state: *mut lua_State, table: c_int, field: &S) -> Result<()>
+where
+    S: AsRef<[u8]> + ?Sized,
+{
+    let field = field.as_ref();
+    let s = StringArg {
+        data: field.as_ptr() as *const c_char,
+        len: field.len(),
+    };
+    super::lua_pushvalue(state, table);
+    super::lua_pushlightuserdata(state, &s as *const StringArg as *mut c_void);
+    super::lua_rotate(state, -3, 2);
+    protect_lua(state, 3, lua_rawsetfield_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_rawinsert(state: *mut lua_State, table: c_int, i: lua_Integer) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -2, 1);
+    super::lua_pushinteger(state, i);
+    protect_lua(state, 3, lua_rawinsert_s)
+}
+
+// Uses 4 stack spaces
+pub unsafe fn lua_rawremove(state: *mut lua_State, table: c_int, i: lua_Integer) -> Result<()> {
+    super::lua_pushvalue(state, table);
+    super::lua_pushinteger(state, i);
+    protect_lua(state, 2, lua_rawremove_s)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn luaL_len(state: *mut lua_State, table: c_int) -> Result<lua_Integer> {
+    super::lua_pushvalue(state, table);
+    protect_lua(state, 1, luaL_len_s)?;
+    let ret = super::lua_tointeger(state, -1);
+    super::lua_pop(state, 1);
+    Ok(ret)
+}
+
+// Uses 3 stack spaces
+pub unsafe fn lua_next(state: *mut lua_State, table: c_int) -> Result<lua_Integer> {
+    super::lua_pushvalue(state, table);
+    super::lua_rotate(state, -2, 1);
+    protect_lua(state, 2, lua_next_s)?;
+    let ret = super::lua_tointeger(state, -1);
+    super::lua_pop(state, 1);
+    Ok(ret)
+}

src/ffi/shim/compat-5.3.c

@@ -0,0 +1,953 @@
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>
+#include "compat-5.3.h"
+
+/* don't compile it again if it already is included via compat53.h */
+#ifndef COMPAT53_C_
+#define COMPAT53_C_
+
+
+
+/* definitions for Lua 5.1 only */
+#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 501
+
+#ifndef COMPAT53_FOPEN_NO_LOCK
+#  if defined(_MSC_VER)
+#    define COMPAT53_FOPEN_NO_LOCK 1
+#  else /* otherwise */
+#    define COMPAT53_FOPEN_NO_LOCK 0
+#  endif /* VC++ only so far */
+#endif /* No-lock fopen_s usage if possible */
+
+#if defined(_MSC_VER) && COMPAT53_FOPEN_NO_LOCK
+#  include <share.h>
+#endif /* VC++ _fsopen for share-allowed file read */
+
+#ifndef COMPAT53_HAVE_STRERROR_R
+#  if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || \
+      (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600) || \
+      defined(__APPLE__)
+#    define COMPAT53_HAVE_STRERROR_R 1
+#  else /* none of the defines matched: define to 0 */
+#    define COMPAT53_HAVE_STRERROR_R 0
+#  endif /* have strerror_r of some form */
+#endif /* strerror_r */
+
+#ifndef COMPAT53_HAVE_STRERROR_S
+#  if defined(_MSC_VER) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L && \
+      defined(__STDC_LIB_EXT1__) && __STDC_LIB_EXT1__)
+#    define COMPAT53_HAVE_STRERROR_S 1
+#  else /* not VC++ or C11 */
+#    define COMPAT53_HAVE_STRERROR_S 0
+#  endif /* strerror_s from VC++ or C11 */
+#endif /* strerror_s */
+
+#ifndef COMPAT53_LUA_FILE_BUFFER_SIZE
+#  define COMPAT53_LUA_FILE_BUFFER_SIZE 4096
+#endif /* Lua File Buffer Size */
+
+
+static char* compat53_strerror (int en, char* buff, size_t sz) {
+#if COMPAT53_HAVE_STRERROR_R
+  /* use strerror_r here, because it's available on these specific platforms */
+  if (sz > 0) {
+    buff[0] = '\0';
+    /* we don't care whether the GNU version or the XSI version is used: */
+    if (strerror_r(en, buff, sz)) {
+      /* Yes, we really DO want to ignore the return value!
+       * GCC makes that extra hard, not even a (void) cast will do. */
+    }
+    if (buff[0] == '\0') {
+      /* Buffer is unchanged, so we probably have called GNU strerror_r which
+       * returned a static constant string. Chances are that strerror will
+       * return the same static constant string and therefore be thread-safe. */
+      return strerror(en);
+    }
+  }
+  return buff; /* sz is 0 *or* strerror_r wrote into the buffer */
+#elif COMPAT53_HAVE_STRERROR_S
+  /* for MSVC and other C11 implementations, use strerror_s since it's
+   * provided by default by the libraries */
+  strerror_s(buff, sz, en);
+  return buff;
+#else
+  /* fallback, but strerror is not guaranteed to be threadsafe due to modifying
+   * errno itself and some impls not locking a static buffer for it ... but most
+   * known systems have threadsafe errno: this might only change if the locale
+   * is changed out from under someone while this function is being called */
+  (void)buff;
+  (void)sz;
+  return strerror(en);
+#endif
+}
+
+
+COMPAT53_API int lua_absindex (lua_State *L, int i) {
+  if (i < 0 && i > LUA_REGISTRYINDEX)
+    i += lua_gettop(L) + 1;
+  return i;
+}
+
+
+static void compat53_call_lua (lua_State *L, char const code[], size_t len,
+                               int nargs, int nret) {
+  lua_rawgetp(L, LUA_REGISTRYINDEX, (void*)code);
+  if (lua_type(L, -1) != LUA_TFUNCTION) {
+    lua_pop(L, 1);
+    if (luaL_loadbuffer(L, code, len, "=none"))
+      lua_error(L);
+    lua_pushvalue(L, -1);
+    lua_rawsetp(L, LUA_REGISTRYINDEX, (void*)code);
+  }
+  lua_insert(L, -nargs-1);
+  lua_call(L, nargs, nret);
+}
+
+
+static const char compat53_arith_code[] =
+  "local op,a,b=...\n"
+  "if op==0 then return a+b\n"
+  "elseif op==1 then return a-b\n"
+  "elseif op==2 then return a*b\n"
+  "elseif op==3 then return a/b\n"
+  "elseif op==4 then return a%b\n"
+  "elseif op==5 then return a^b\n"
+  "elseif op==6 then return -a\n"
+  "end\n";
+
+COMPAT53_API void lua_arith (lua_State *L, int op) {
+  if (op < LUA_OPADD || op > LUA_OPUNM)
+    luaL_error(L, "invalid 'op' argument for lua_arith");
+  luaL_checkstack(L, 5, "not enough stack slots");
+  if (op == LUA_OPUNM)
+    lua_pushvalue(L, -1);
+  lua_pushnumber(L, op);
+  lua_insert(L, -3);
+  compat53_call_lua(L, compat53_arith_code,
+                    sizeof(compat53_arith_code)-1, 3, 1);
+}
+
+
+static const char compat53_compare_code[] =
+  "local a,b=...\n"
+  "return a<=b\n";
+
+COMPAT53_API int lua_compare (lua_State *L, int idx1, int idx2, int op) {
+  int result = 0;
+  switch (op) {
+    case LUA_OPEQ:
+      return lua_equal(L, idx1, idx2);
+    case LUA_OPLT:
+      return lua_lessthan(L, idx1, idx2);
+    case LUA_OPLE:
+      luaL_checkstack(L, 5, "not enough stack slots");
+      idx1 = lua_absindex(L, idx1);
+      idx2 = lua_absindex(L, idx2);
+      lua_pushvalue(L, idx1);
+      lua_pushvalue(L, idx2);
+      compat53_call_lua(L, compat53_compare_code,
+                        sizeof(compat53_compare_code)-1, 2, 1);
+      result = lua_toboolean(L, -1);
+      lua_pop(L, 1);
+      return result;
+    default:
+      luaL_error(L, "invalid 'op' argument for lua_compare");
+  }
+  return 0;
+}
+
+
+COMPAT53_API void lua_copy (lua_State *L, int from, int to) {
+  int abs_to = lua_absindex(L, to);
+  luaL_checkstack(L, 1, "not enough stack slots");
+  lua_pushvalue(L, from);
+  lua_replace(L, abs_to);
+}
+
+
+COMPAT53_API void lua_len (lua_State *L, int i) {
+  switch (lua_type(L, i)) {
+    case LUA_TSTRING:
+      lua_pushnumber(L, (lua_Number)lua_objlen(L, i));
+      break;
+    case LUA_TTABLE:
+      if (!luaL_callmeta(L, i, "__len"))
+        lua_pushnumber(L, (lua_Number)lua_objlen(L, i));
+      break;
+    case LUA_TUSERDATA:
+      if (luaL_callmeta(L, i, "__len"))
+        break;
+      /* FALLTHROUGH */
+    default:
+      luaL_error(L, "attempt to get length of a %s value",
+                 lua_typename(L, lua_type(L, i)));
+  }
+}
+
+
+COMPAT53_API int lua_rawgetp (lua_State *L, int i, const void *p) {
+  int abs_i = lua_absindex(L, i);
+  lua_pushlightuserdata(L, (void*)p);
+  lua_rawget(L, abs_i);
+  return lua_type(L, -1);
+}
+
+COMPAT53_API void lua_rawsetp (lua_State *L, int i, const void *p) {
+  int abs_i = lua_absindex(L, i);
+  luaL_checkstack(L, 1, "not enough stack slots");
+  lua_pushlightuserdata(L, (void*)p);
+  lua_insert(L, -2);
+  lua_rawset(L, abs_i);
+}
+
+
+COMPAT53_API lua_Number lua_tonumberx (lua_State *L, int i, int *isnum) {
+  lua_Number n = lua_tonumber(L, i);
+  if (isnum != NULL) {
+    *isnum = (n != 0 || lua_isnumber(L, i));
+  }
+  return n;
+}
+
+
+COMPAT53_API void luaL_checkversion (lua_State *L) {
+  (void)L;
+}
+
+
+COMPAT53_API void luaL_checkstack (lua_State *L, int sp, const char *msg) {
+  if (!lua_checkstack(L, sp+LUA_MINSTACK)) {
+    if (msg != NULL)
+      luaL_error(L, "stack overflow (%s)", msg);
+    else {
+      lua_pushliteral(L, "stack overflow");
+      lua_error(L);
+    }
+  }
+}
+
+
+COMPAT53_API int luaL_getsubtable (lua_State *L, int i, const char *name) {
+  int abs_i = lua_absindex(L, i);
+  luaL_checkstack(L, 3, "not enough stack slots");
+  lua_pushstring(L, name);
+  lua_gettable(L, abs_i);
+  if (lua_istable(L, -1))
+    return 1;
+  lua_pop(L, 1);
+  lua_newtable(L);
+  lua_pushstring(L, name);
+  lua_pushvalue(L, -2);
+  lua_settable(L, abs_i);
+  return 0;
+}
+
+
+COMPAT53_API lua_Integer luaL_len (lua_State *L, int i) {
+  lua_Integer res = 0;
+  int isnum = 0;
+  luaL_checkstack(L, 1, "not enough stack slots");
+  lua_len(L, i);
+  res = lua_tointegerx(L, -1, &isnum);
+  lua_pop(L, 1);
+  if (!isnum)
+    luaL_error(L, "object length is not an integer");
+  return res;
+}
+
+
+COMPAT53_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
+  luaL_checkstack(L, nup+1, "too many upvalues");
+  for (; l->name != NULL; l++) {  /* fill the table with given functions */
+    int i;
+    lua_pushstring(L, l->name);
+    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
+      lua_pushvalue(L, -(nup + 1));
+    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
+    lua_settable(L, -(nup + 3)); /* table must be below the upvalues, the name and the closure */
+  }
+  lua_pop(L, nup);  /* remove upvalues */
+}
+
+
+COMPAT53_API void luaL_setmetatable (lua_State *L, const char *tname) {
+  luaL_checkstack(L, 1, "not enough stack slots");
+  luaL_getmetatable(L, tname);
+  lua_setmetatable(L, -2);
+}
+
+
+COMPAT53_API void *luaL_testudata (lua_State *L, int i, const char *tname) {
+  void *p = lua_touserdata(L, i);
+  luaL_checkstack(L, 2, "not enough stack slots");
+  if (p == NULL || !lua_getmetatable(L, i))
+    return NULL;
+  else {
+    int res = 0;
+    luaL_getmetatable(L, tname);
+    res = lua_rawequal(L, -1, -2);
+    lua_pop(L, 2);
+    if (!res)
+      p = NULL;
+  }
+  return p;
+}
+
+
+static int compat53_countlevels (lua_State *L) {
+  lua_Debug ar;
+  int li = 1, le = 1;
+  /* find an upper bound */
+  while (lua_getstack(L, le, &ar)) { li = le; le *= 2; }
+  /* do a binary search */
+  while (li < le) {
+    int m = (li + le)/2;
+    if (lua_getstack(L, m, &ar)) li = m + 1;
+    else le = m;
+  }
+  return le - 1;
+}
+
+static int compat53_findfield (lua_State *L, int objidx, int level) {
+  if (level == 0 || !lua_istable(L, -1))
+    return 0;  /* not found */
+  lua_pushnil(L);  /* start 'next' loop */
+  while (lua_next(L, -2)) {  /* for each pair in table */
+    if (lua_type(L, -2) == LUA_TSTRING) {  /* ignore non-string keys */
+      if (lua_rawequal(L, objidx, -1)) {  /* found object? */
+        lua_pop(L, 1);  /* remove value (but keep name) */
+        return 1;
+      }
+      else if (compat53_findfield(L, objidx, level - 1)) {  /* try recursively */
+        lua_remove(L, -2);  /* remove table (but keep name) */
+        lua_pushliteral(L, ".");
+        lua_insert(L, -2);  /* place '.' between the two names */
+        lua_concat(L, 3);
+        return 1;
+      }
+    }
+    lua_pop(L, 1);  /* remove value */
+  }
+  return 0;  /* not found */
+}
+
+static int compat53_pushglobalfuncname (lua_State *L, lua_Debug *ar) {
+  int top = lua_gettop(L);
+  lua_getinfo(L, "f", ar);  /* push function */
+  lua_pushvalue(L, LUA_GLOBALSINDEX);
+  if (compat53_findfield(L, top + 1, 2)) {
+    lua_copy(L, -1, top + 1);  /* move name to proper place */
+    lua_pop(L, 2);  /* remove pushed values */
+    return 1;
+  }
+  else {
+    lua_settop(L, top);  /* remove function and global table */
+    return 0;
+  }
+}
+
+static void compat53_pushfuncname (lua_State *L, lua_Debug *ar) {
+  if (*ar->namewhat != '\0')  /* is there a name? */
+    lua_pushfstring(L, "function " LUA_QS, ar->name);
+  else if (*ar->what == 'm')  /* main? */
+      lua_pushliteral(L, "main chunk");
+  else if (*ar->what == 'C') {
+    if (compat53_pushglobalfuncname(L, ar)) {
+      lua_pushfstring(L, "function " LUA_QS, lua_tostring(L, -1));
+      lua_remove(L, -2);  /* remove name */
+    }
+    else
+      lua_pushliteral(L, "?");
+  }
+  else
+    lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
+}
+
+#define COMPAT53_LEVELS1 12  /* size of the first part of the stack */
+#define COMPAT53_LEVELS2 10  /* size of the second part of the stack */
+
+COMPAT53_API void luaL_traceback (lua_State *L, lua_State *L1,
+                                  const char *msg, int level) {
+  lua_Debug ar;
+  int top = lua_gettop(L);
+  int numlevels = compat53_countlevels(L1);
+  int mark = (numlevels > COMPAT53_LEVELS1 + COMPAT53_LEVELS2) ? COMPAT53_LEVELS1 : 0;
+  if (msg) lua_pushfstring(L, "%s\n", msg);
+  lua_pushliteral(L, "stack traceback:");
+  while (lua_getstack(L1, level++, &ar)) {
+    if (level == mark) {  /* too many levels? */
+      lua_pushliteral(L, "\n\t...");  /* add a '...' */
+      level = numlevels - COMPAT53_LEVELS2;  /* and skip to last ones */
+    }
+    else {
+      lua_getinfo(L1, "Slnt", &ar);
+      lua_pushfstring(L, "\n\t%s:", ar.short_src);
+      if (ar.currentline > 0)
+        lua_pushfstring(L, "%d:", ar.currentline);
+      lua_pushliteral(L, " in ");
+      compat53_pushfuncname(L, &ar);
+      lua_concat(L, lua_gettop(L) - top);
+    }
+  }
+  lua_concat(L, lua_gettop(L) - top);
+}
+
+
+COMPAT53_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {
+  const char *serr = NULL;
+  int en = errno;  /* calls to Lua API may change this value */
+  char buf[512] = { 0 };
+  if (stat) {
+    lua_pushboolean(L, 1);
+    return 1;
+  }
+  else {
+    lua_pushnil(L);
+    serr = compat53_strerror(en, buf, sizeof(buf));
+    if (fname)
+      lua_pushfstring(L, "%s: %s", fname, serr);
+    else
+      lua_pushstring(L, serr);
+    lua_pushnumber(L, (lua_Number)en);
+    return 3;
+  }
+}
+
+
+static int compat53_checkmode (lua_State *L, const char *mode, const char *modename, int err) {
+  if (mode && strchr(mode, modename[0]) == NULL) {
+    lua_pushfstring(L, "attempt to load a %s chunk (mode is '%s')", modename, mode);
+    return err;
+  }
+  return LUA_OK;
+}
+
+
+typedef struct {
+  lua_Reader reader;
+  void *ud;
+  int has_peeked_data;
+  const char *peeked_data;
+  size_t peeked_data_size;
+} compat53_reader_data;
+
+
+static const char *compat53_reader (lua_State *L, void *ud, size_t *size) {
+  compat53_reader_data *data = (compat53_reader_data *)ud;
+  if (data->has_peeked_data) {
+    data->has_peeked_data = 0;
+    *size = data->peeked_data_size;
+    return data->peeked_data;
+  } else
+    return data->reader(L, data->ud, size);
+}
+
+
+COMPAT53_API int lua_load (lua_State *L, lua_Reader reader, void *data, const char *source, const char *mode) {
+  int status = LUA_OK;
+  compat53_reader_data compat53_data = { 0, NULL, 1, 0, 0 };
+  compat53_data.reader = reader;
+  compat53_data.ud = data;
+  compat53_data.peeked_data = reader(L, data, &(compat53_data.peeked_data_size));
+  if (compat53_data.peeked_data && compat53_data.peeked_data_size &&
+      compat53_data.peeked_data[0] == LUA_SIGNATURE[0]) /* binary file? */
+      status = compat53_checkmode(L, mode, "binary", LUA_ERRSYNTAX);
+  else
+      status = compat53_checkmode(L, mode, "text", LUA_ERRSYNTAX);
+  if (status != LUA_OK)
+    return status;
+  /* we need to call the original 5.1 version of lua_load! */
+#undef lua_load
+  return lua_load(L, compat53_reader, &compat53_data, source);
+#define lua_load COMPAT53_CONCAT(COMPAT53_PREFIX, _load_53)
+}
+
+
+typedef struct {
+  int n;  /* number of pre-read characters */
+  FILE *f;  /* file being read */
+  char buff[COMPAT53_LUA_FILE_BUFFER_SIZE];  /* area for reading file */
+} compat53_LoadF;
+
+
+static const char *compat53_getF (lua_State *L, void *ud, size_t *size) {
+  compat53_LoadF *lf = (compat53_LoadF *)ud;
+  (void)L;  /* not used */
+  if (lf->n > 0) {  /* are there pre-read characters to be read? */
+    *size = lf->n;  /* return them (chars already in buffer) */
+    lf->n = 0;  /* no more pre-read characters */
+  }
+  else {  /* read a block from file */
+    /* 'fread' can return > 0 *and* set the EOF flag. If next call to
+       'compat53_getF' called 'fread', it might still wait for user input.
+       The next check avoids this problem. */
+    if (feof(lf->f)) return NULL;
+    *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */
+  }
+  return lf->buff;
+}
+
+
+static int compat53_errfile (lua_State *L, const char *what, int fnameindex) {
+  char buf[512] = {0};
+  const char *serr = compat53_strerror(errno, buf, sizeof(buf));
+  const char *filename = lua_tostring(L, fnameindex) + 1;
+  lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
+  lua_remove(L, fnameindex);
+  return LUA_ERRFILE;
+}
+
+
+static int compat53_skipBOM (compat53_LoadF *lf) {
+  const char *p = "\xEF\xBB\xBF";  /* UTF-8 BOM mark */
+  int c;
+  lf->n = 0;
+  do {
+    c = getc(lf->f);
+    if (c == EOF || c != *(const unsigned char *)p++) return c;
+    lf->buff[lf->n++] = (char)c;  /* to be read by the parser */
+  } while (*p != '\0');
+  lf->n = 0;  /* prefix matched; discard it */
+  return getc(lf->f);  /* return next character */
+}
+
+
+/*
+** reads the first character of file 'f' and skips an optional BOM mark
+** in its beginning plus its first line if it starts with '#'. Returns
+** true if it skipped the first line.  In any case, '*cp' has the
+** first "valid" character of the file (after the optional BOM and
+** a first-line comment).
+*/
+static int compat53_skipcomment (compat53_LoadF *lf, int *cp) {
+  int c = *cp = compat53_skipBOM(lf);
+  if (c == '#') {  /* first line is a comment (Unix exec. file)? */
+    do {  /* skip first line */
+      c = getc(lf->f);
+    } while (c != EOF && c != '\n');
+    *cp = getc(lf->f);  /* skip end-of-line, if present */
+    return 1;  /* there was a comment */
+  }
+  else return 0;  /* no comment */
+}
+
+
+COMPAT53_API int luaL_loadfilex (lua_State *L, const char *filename, const char *mode) {
+  compat53_LoadF lf;
+  int status, readstatus;
+  int c;
+  int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
+  if (filename == NULL) {
+    lua_pushliteral(L, "=stdin");
+    lf.f = stdin;
+  }
+  else {
+    lua_pushfstring(L, "@%s", filename);
+#if defined(_MSC_VER)
+    /* This code is here to stop a deprecation error that stops builds
+     * if a certain macro is defined. While normally not caring would
+     * be best, some header-only libraries and builds can't afford to
+     * dictate this to the user. A quick check shows that fopen_s this
+     * goes back to VS 2005, and _fsopen goes back to VS 2003 .NET,
+     * possibly even before that so we don't need to do any version
+     * number checks, since this has been there since forever.  */
+
+    /* TO USER: if you want the behavior of typical fopen_s/fopen,
+     * which does lock the file on VC++, define the macro used below to 0 */
+#if COMPAT53_FOPEN_NO_LOCK
+    lf.f = _fsopen(filename, "r", _SH_DENYNO); /* do not lock the file in any way */
+    if (lf.f == NULL)
+      return compat53_errfile(L, "open", fnameindex);
+#else /* use default locking version */
+    if (fopen_s(&lf.f, filename, "r") != 0)
+      return compat53_errfile(L, "open", fnameindex);
+#endif /* Locking vs. No-locking fopen variants */
+#else
+    lf.f = fopen(filename, "r"); /* default stdlib doesn't forcefully lock files here */
+    if (lf.f == NULL) return compat53_errfile(L, "open", fnameindex);
+#endif
+  }
+  if (compat53_skipcomment(&lf, &c))  /* read initial portion */
+    lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */
+  if (c == LUA_SIGNATURE[0] && filename) {  /* binary file? */
+#if defined(_MSC_VER)
+    if (freopen_s(&lf.f, filename, "rb", lf.f) != 0)
+      return compat53_errfile(L, "reopen", fnameindex);
+#else
+    lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
+    if (lf.f == NULL) return compat53_errfile(L, "reopen", fnameindex);
+#endif
+    compat53_skipcomment(&lf, &c);  /* re-read initial portion */
+  }
+  if (c != EOF)
+    lf.buff[lf.n++] = (char)c;  /* 'c' is the first character of the stream */
+  status = lua_load(L, &compat53_getF, &lf, lua_tostring(L, -1), mode);
+  readstatus = ferror(lf.f);
+  if (filename) fclose(lf.f);  /* close file (even in case of errors) */
+  if (readstatus) {
+    lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
+    return compat53_errfile(L, "read", fnameindex);
+  }
+  lua_remove(L, fnameindex);
+  return status;
+}
+
+
+COMPAT53_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t sz, const char *name, const char *mode) {
+  int status = LUA_OK;
+  if (sz > 0 && buff[0] == LUA_SIGNATURE[0]) {
+    status = compat53_checkmode(L, mode, "binary", LUA_ERRSYNTAX);
+  }
+  else {
+    status = compat53_checkmode(L, mode, "text", LUA_ERRSYNTAX);
+  }
+  if (status != LUA_OK)
+    return status;
+  return luaL_loadbuffer(L, buff, sz, name);
+}
+
+
+#if !defined(l_inspectstat) && \
+    (defined(unix) || defined(__unix) || defined(__unix__) || \
+     defined(__TOS_AIX__) || defined(_SYSTYPE_BSD) || \
+     (defined(__APPLE__) && defined(__MACH__)))
+/* some form of unix; check feature macros in unistd.h for details */
+#  include <unistd.h>
+/* check posix version; the relevant include files and macros probably
+ * were available before 2001, but I'm not sure */
+#  if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
+#    include <sys/wait.h>
+#    define l_inspectstat(stat,what) \
+  if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
+  else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }
+#  endif
+#endif
+
+/* provide default (no-op) version */
+#if !defined(l_inspectstat)
+#  define l_inspectstat(stat,what) ((void)0)
+#endif
+
+
+COMPAT53_API int luaL_execresult (lua_State *L, int stat) {
+  const char *what = "exit";
+  if (stat == -1)
+    return luaL_fileresult(L, 0, NULL);
+  else {
+    l_inspectstat(stat, what);
+    if (*what == 'e' && stat == 0)
+      lua_pushboolean(L, 1);
+    else
+      lua_pushnil(L);
+    lua_pushstring(L, what);
+    lua_pushinteger(L, stat);
+    return 3;
+  }
+}
+
+
+COMPAT53_API void luaL_buffinit (lua_State *L, luaL_Buffer_53 *B) {
+  /* make it crash if used via pointer to a 5.1-style luaL_Buffer */
+  B->b.p = NULL;
+  B->b.L = NULL;
+  B->b.lvl = 0;
+  /* reuse the buffer from the 5.1-style luaL_Buffer though! */
+  B->ptr = B->b.buffer;
+  B->capacity = LUAL_BUFFERSIZE;
+  B->nelems = 0;
+  B->L2 = L;
+}
+
+
+COMPAT53_API char *luaL_prepbuffsize (luaL_Buffer_53 *B, size_t s) {
+  if (B->capacity - B->nelems < s) { /* needs to grow */
+    char* newptr = NULL;
+    size_t newcap = B->capacity * 2;
+    if (newcap - B->nelems < s)
+      newcap = B->nelems + s;
+    if (newcap < B->capacity) /* overflow */
+      luaL_error(B->L2, "buffer too large");
+    newptr = (char*)lua_newuserdata(B->L2, newcap);
+    memcpy(newptr, B->ptr, B->nelems);
+    if (B->ptr != B->b.buffer)
+      lua_replace(B->L2, -2); /* remove old buffer */
+    B->ptr = newptr;
+    B->capacity = newcap;
+  }
+  return B->ptr+B->nelems;
+}
+
+
+COMPAT53_API void luaL_addlstring (luaL_Buffer_53 *B, const char *s, size_t l) {
+  memcpy(luaL_prepbuffsize(B, l), s, l);
+  luaL_addsize(B, l);
+}
+
+
+COMPAT53_API void luaL_addvalue (luaL_Buffer_53 *B) {
+  size_t len = 0;
+  const char *s = lua_tolstring(B->L2, -1, &len);
+  if (!s)
+    luaL_error(B->L2, "cannot convert value to string");
+  if (B->ptr != B->b.buffer)
+    lua_insert(B->L2, -2); /* userdata buffer must be at stack top */
+  luaL_addlstring(B, s, len);
+  lua_remove(B->L2, B->ptr != B->b.buffer ? -2 : -1);
+}
+
+
+void luaL_pushresult (luaL_Buffer_53 *B) {
+  lua_pushlstring(B->L2, B->ptr, B->nelems);
+  if (B->ptr != B->b.buffer)
+    lua_replace(B->L2, -2); /* remove userdata buffer */
+}
+
+
+#endif /* Lua 5.1 */
+
+
+
+/* definitions for Lua 5.1 and Lua 5.2 */
+#if defined( LUA_VERSION_NUM ) && LUA_VERSION_NUM <= 502
+
+
+COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i) {
+  index = lua_absindex(L, index);
+  lua_pushinteger(L, i);
+  lua_gettable(L, index);
+  return lua_type(L, -1);
+}
+
+
+#ifndef LUA_EXTRASPACE
+#define LUA_EXTRASPACE (sizeof(void*))
+#endif
+
+COMPAT53_API void *lua_getextraspace (lua_State *L) {
+  int is_main = 0;
+  void *ptr = NULL;
+  luaL_checkstack(L, 4, "not enough stack slots available");
+  lua_pushliteral(L, "__compat53_extraspace");
+  lua_pushvalue(L, -1);
+  lua_rawget(L, LUA_REGISTRYINDEX);
+  if (!lua_istable(L, -1)) {
+    lua_pop(L, 1);
+    lua_createtable(L, 0, 2);
+    lua_createtable(L, 0, 1);
+    lua_pushliteral(L, "k");
+    lua_setfield(L, -2, "__mode");
+    lua_setmetatable(L, -2);
+    lua_pushvalue(L, -2);
+    lua_pushvalue(L, -2);
+    lua_rawset(L, LUA_REGISTRYINDEX);
+  }
+  lua_replace(L, -2);
+  is_main = lua_pushthread(L);
+  lua_rawget(L, -2);
+  ptr = lua_touserdata(L, -1);
+  if (!ptr) {
+    lua_pop(L, 1);
+    ptr = lua_newuserdata(L, LUA_EXTRASPACE);
+    if (is_main) {
+      memset(ptr, '\0', LUA_EXTRASPACE);
+      lua_pushthread(L);
+      lua_pushvalue(L, -2);
+      lua_rawset(L, -4);
+      lua_pushboolean(L, 1);
+      lua_pushvalue(L, -2);
+      lua_rawset(L, -4);
+    } else {
+      void* mptr = NULL;
+      lua_pushboolean(L, 1);
+      lua_rawget(L, -3);
+      mptr = lua_touserdata(L, -1);
+      if (mptr)
+        memcpy(ptr, mptr, LUA_EXTRASPACE);
+      else
+        memset(ptr, '\0', LUA_EXTRASPACE);
+      lua_pop(L, 1);
+      lua_pushthread(L);
+      lua_pushvalue(L, -2);
+      lua_rawset(L, -4);
+    }
+  }
+  lua_pop(L, 2);
+  return ptr;
+}
+
+
+COMPAT53_API int lua_isinteger (lua_State *L, int index) {
+  if (lua_type(L, index) == LUA_TNUMBER) {
+    lua_Number n = lua_tonumber(L, index);
+    lua_Integer i = lua_tointeger(L, index);
+    if (i == n)
+      return 1;
+  }
+  return 0;
+}
+
+
+COMPAT53_API lua_Integer lua_tointegerx (lua_State *L, int i, int *isnum) {
+  int ok = 0;
+  lua_Number n = lua_tonumberx(L, i, &ok);
+  if (ok) {
+    if (n == (lua_Integer)n) {
+      if (isnum)
+        *isnum = 1;
+      return (lua_Integer)n;
+    }
+  }
+  if (isnum)
+    *isnum = 0;
+  return 0;
+}
+
+
+static void compat53_reverse (lua_State *L, int a, int b) {
+  for (; a < b; ++a, --b) {
+    lua_pushvalue(L, a);
+    lua_pushvalue(L, b);
+    lua_replace(L, a);
+    lua_replace(L, b);
+  }
+}
+
+
+COMPAT53_API void lua_rotate (lua_State *L, int idx, int n) {
+  int n_elems = 0;
+  idx = lua_absindex(L, idx);
+  n_elems = lua_gettop(L)-idx+1;
+  if (n < 0)
+    n += n_elems;
+  if ( n > 0 && n < n_elems) {
+    luaL_checkstack(L, 2, "not enough stack slots available");
+    n = n_elems - n;
+    compat53_reverse(L, idx, idx+n-1);
+    compat53_reverse(L, idx+n, idx+n_elems-1);
+    compat53_reverse(L, idx, idx+n_elems-1);
+  }
+}
+
+
+COMPAT53_API void lua_seti (lua_State *L, int index, lua_Integer i) {
+  luaL_checkstack(L, 1, "not enough stack slots available");
+  index = lua_absindex(L, index);
+  lua_pushinteger(L, i);
+  lua_insert(L, -2);
+  lua_settable(L, index);
+}
+
+
+#if !defined(lua_str2number)
+#  define lua_str2number(s, p)  strtod((s), (p))
+#endif
+
+COMPAT53_API size_t lua_stringtonumber (lua_State *L, const char *s) {
+  char* endptr;
+  lua_Number n = lua_str2number(s, &endptr);
+  if (endptr != s) {
+    while (*endptr != '\0' && isspace((unsigned char)*endptr))
+      ++endptr;
+    if (*endptr == '\0') {
+      lua_pushnumber(L, n);
+      return endptr - s + 1;
+    }
+  }
+  return 0;
+}
+
+
+COMPAT53_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
+  if (!luaL_callmeta(L, idx, "__tostring")) {
+    int t = lua_type(L, idx), tt = 0;
+    char const* name = NULL;
+    switch (t) {
+      case LUA_TNIL:
+        lua_pushliteral(L, "nil");
+        break;
+      case LUA_TSTRING:
+      case LUA_TNUMBER:
+        lua_pushvalue(L, idx);
+        break;
+      case LUA_TBOOLEAN:
+        if (lua_toboolean(L, idx))
+          lua_pushliteral(L, "true");
+        else
+          lua_pushliteral(L, "false");
+        break;
+      default:
+        tt = luaL_getmetafield(L, idx, "__name");
+        name = (tt == LUA_TSTRING) ? lua_tostring(L, -1) : lua_typename(L, t);
+        lua_pushfstring(L, "%s: %p", name, lua_topointer(L, idx));
+        if (tt != LUA_TNIL)
+          lua_replace(L, -2);
+        break;
+    }
+  } else {
+    if (!lua_isstring(L, -1))
+      luaL_error(L, "'__tostring' must return a string");
+  }
+  return lua_tolstring(L, -1, len);
+}
+
+
+COMPAT53_API void luaL_requiref (lua_State *L, const char *modname,
+                                 lua_CFunction openf, int glb) {
+  luaL_checkstack(L, 3, "not enough stack slots available");
+  luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");
+  if (lua_getfield(L, -1, modname) == LUA_TNIL) {
+    lua_pop(L, 1);
+    lua_pushcfunction(L, openf);
+    lua_pushstring(L, modname);
+#ifndef COMPAT53_LUAJIT
+    lua_call(L, 1, 1);
+    lua_pushvalue(L, -1);
+    lua_setfield(L, -3, modname);
+#else
+    lua_call(L, 1, 0);
+    lua_getfield(L, -1, modname);
+#endif /* COMPAT53_LUAJIT */
+  }
+  if (glb) {
+    lua_pushvalue(L, -1);
+    lua_setglobal(L, modname);
+  }
+  lua_replace(L, -2);
+}
+
+
+#endif /* Lua 5.1 and 5.2 */
+
+
+#endif /* COMPAT53_C_ */
+
+
+/*********************************************************************
+* This file contains parts of Lua 5.2's and Lua 5.3's source code:
+*
+* Copyright (C) 1994-2014 Lua.org, PUC-Rio.
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be
+* included in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*********************************************************************/
+

src/ffi/shim/compat-5.3.h

@@ -0,0 +1,424 @@
+#ifndef COMPAT53_H_
+#define COMPAT53_H_
+
+#include <stddef.h>
+#include <limits.h>
+#include <string.h>
+#if defined(__cplusplus) && !defined(COMPAT53_LUA_CPP)
+extern "C" {
+#endif
+#include <lua.h>
+#include <lauxlib.h>
+#include <lualib.h>
+#if defined(__cplusplus) && !defined(COMPAT53_LUA_CPP)
+}
+#endif
+
+
+#undef COMPAT53_INCLUDE_SOURCE
+#if defined(COMPAT53_PREFIX)
+/* - change the symbol names of functions to avoid linker conflicts
+ * - compat-5.3.c needs to be compiled (and linked) separately
+ */
+#  if !defined(COMPAT53_API)
+#    define COMPAT53_API extern
+#  endif
+#else /* COMPAT53_PREFIX */
+/* - make all functions static and include the source.
+ * - compat-5.3.c doesn't need to be compiled (and linked) separately
+ */
+#  define COMPAT53_PREFIX compat53
+#  undef COMPAT53_API
+#  if defined(__GNUC__) || defined(__clang__)
+#    define COMPAT53_API __attribute__((__unused__)) static
+#  else
+#    define COMPAT53_API static
+#  endif
+#  define COMPAT53_INCLUDE_SOURCE
+#endif /* COMPAT53_PREFIX */
+
+#define COMPAT53_CONCAT_HELPER(a, b) a##b
+#define COMPAT53_CONCAT(a, b) COMPAT53_CONCAT_HELPER(a, b)
+
+
+
+/* declarations for Lua 5.1 */
+#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 501
+
+/* XXX not implemented:
+ * lua_arith (new operators)
+ * lua_upvalueid
+ * lua_upvaluejoin
+ * lua_version
+ * lua_yieldk
+ */
+
+#ifndef LUA_OK
+#  define LUA_OK 0
+#endif
+#ifndef LUA_OPADD
+#  define LUA_OPADD 0
+#endif
+#ifndef LUA_OPSUB
+#  define LUA_OPSUB 1
+#endif
+#ifndef LUA_OPMUL
+#  define LUA_OPMUL 2
+#endif
+#ifndef LUA_OPDIV
+#  define LUA_OPDIV 3
+#endif
+#ifndef LUA_OPMOD
+#  define LUA_OPMOD 4
+#endif
+#ifndef LUA_OPPOW
+#  define LUA_OPPOW 5
+#endif
+#ifndef LUA_OPUNM
+#  define LUA_OPUNM 6
+#endif
+#ifndef LUA_OPEQ
+#  define LUA_OPEQ 0
+#endif
+#ifndef LUA_OPLT
+#  define LUA_OPLT 1
+#endif
+#ifndef LUA_OPLE
+#  define LUA_OPLE 2
+#endif
+
+/* LuaJIT/Lua 5.1 does not have the updated
+ * error codes for thread status/function returns (but some patched versions do)
+ * define it only if it's not found
+ */
+#if !defined(LUA_ERRGCMM)
+/* Use + 2 because in some versions of Lua (Lua 5.1)
+ * LUA_ERRFILE is defined as (LUA_ERRERR+1)
+ * so we need to avoid it (LuaJIT might have something at this
+ * integer value too)
+ */
+#  define LUA_ERRGCMM (LUA_ERRERR + 2)
+#endif /* LUA_ERRGCMM define */
+
+typedef size_t lua_Unsigned;
+
+typedef struct luaL_Buffer_53 {
+  luaL_Buffer b; /* make incorrect code crash! */
+  char *ptr;
+  size_t nelems;
+  size_t capacity;
+  lua_State *L2;
+} luaL_Buffer_53;
+#define luaL_Buffer luaL_Buffer_53
+
+/* In PUC-Rio 5.1, userdata is a simple FILE*
+ * In LuaJIT, it's a struct where the first member is a FILE*
+ * We can't support the `closef` member
+ */
+typedef struct luaL_Stream {
+  FILE *f;
+} luaL_Stream;
+
+#define lua_absindex COMPAT53_CONCAT(COMPAT53_PREFIX, _absindex)
+COMPAT53_API int lua_absindex (lua_State *L, int i);
+
+#define lua_arith COMPAT53_CONCAT(COMPAT53_PREFIX, _arith)
+COMPAT53_API void lua_arith (lua_State *L, int op);
+
+#define lua_compare COMPAT53_CONCAT(COMPAT53_PREFIX, _compare)
+COMPAT53_API int lua_compare (lua_State *L, int idx1, int idx2, int op);
+
+#define lua_copy COMPAT53_CONCAT(COMPAT53_PREFIX, _copy)
+COMPAT53_API void lua_copy (lua_State *L, int from, int to);
+
+#define lua_getuservalue(L, i) \
+  (lua_getfenv((L), (i)), lua_type((L), -1))
+#define lua_setuservalue(L, i) \
+  (luaL_checktype((L), -1, LUA_TTABLE), lua_setfenv((L), (i)))
+
+#define lua_len COMPAT53_CONCAT(COMPAT53_PREFIX, _len)
+COMPAT53_API void lua_len (lua_State *L, int i);
+
+#define lua_pushstring(L, s) \
+  (lua_pushstring((L), (s)), lua_tostring((L), -1))
+
+#define lua_pushlstring(L, s, len) \
+  ((((len) == 0) ? lua_pushlstring((L), "", 0) : lua_pushlstring((L), (s), (len))), lua_tostring((L), -1))
+
+#ifndef luaL_newlibtable
+#  define luaL_newlibtable(L, l) \
+  (lua_createtable((L), 0, sizeof((l))/sizeof(*(l))-1))
+#endif
+#ifndef luaL_newlib
+#  define luaL_newlib(L, l) \
+  (luaL_newlibtable((L), (l)), luaL_register((L), NULL, (l)))
+#endif
+
+#define lua_pushglobaltable(L) \
+  lua_pushvalue((L), LUA_GLOBALSINDEX)
+
+#define lua_rawgetp COMPAT53_CONCAT(COMPAT53_PREFIX, _rawgetp)
+COMPAT53_API int lua_rawgetp (lua_State *L, int i, const void *p);
+
+#define lua_rawsetp COMPAT53_CONCAT(COMPAT53_PREFIX, _rawsetp)
+COMPAT53_API void lua_rawsetp(lua_State *L, int i, const void *p);
+
+#define lua_rawlen(L, i) lua_objlen((L), (i))
+
+#define lua_tointeger(L, i) lua_tointegerx((L), (i), NULL)
+
+#define lua_tonumberx COMPAT53_CONCAT(COMPAT53_PREFIX, _tonumberx)
+COMPAT53_API lua_Number lua_tonumberx (lua_State *L, int i, int *isnum);
+
+#define luaL_checkversion COMPAT53_CONCAT(COMPAT53_PREFIX, L_checkversion)
+COMPAT53_API void luaL_checkversion (lua_State *L);
+
+#define lua_load COMPAT53_CONCAT(COMPAT53_PREFIX, _load_53)
+COMPAT53_API int lua_load (lua_State *L, lua_Reader reader, void *data, const char* source, const char* mode);
+
+#define luaL_loadfilex COMPAT53_CONCAT(COMPAT53_PREFIX, L_loadfilex)
+COMPAT53_API int luaL_loadfilex (lua_State *L, const char *filename, const char *mode);
+
+#define luaL_loadbufferx COMPAT53_CONCAT(COMPAT53_PREFIX, L_loadbufferx)
+COMPAT53_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t sz, const char *name, const char *mode);
+
+#define luaL_checkstack COMPAT53_CONCAT(COMPAT53_PREFIX, L_checkstack_53)
+COMPAT53_API void luaL_checkstack (lua_State *L, int sp, const char *msg);
+
+#define luaL_getsubtable COMPAT53_CONCAT(COMPAT53_PREFIX, L_getsubtable)
+COMPAT53_API int luaL_getsubtable (lua_State* L, int i, const char *name);
+
+#define luaL_len COMPAT53_CONCAT(COMPAT53_PREFIX, L_len)
+COMPAT53_API lua_Integer luaL_len (lua_State *L, int i);
+
+#define luaL_setfuncs COMPAT53_CONCAT(COMPAT53_PREFIX, L_setfuncs)
+COMPAT53_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);
+
+#define luaL_setmetatable COMPAT53_CONCAT(COMPAT53_PREFIX, L_setmetatable)
+COMPAT53_API void luaL_setmetatable (lua_State *L, const char *tname);
+
+#define luaL_testudata COMPAT53_CONCAT(COMPAT53_PREFIX, L_testudata)
+COMPAT53_API void *luaL_testudata (lua_State *L, int i, const char *tname);
+
+#define luaL_traceback COMPAT53_CONCAT(COMPAT53_PREFIX, L_traceback)
+COMPAT53_API void luaL_traceback (lua_State *L, lua_State *L1, const char *msg, int level);
+
+#define luaL_fileresult COMPAT53_CONCAT(COMPAT53_PREFIX, L_fileresult)
+COMPAT53_API int luaL_fileresult (lua_State *L, int stat, const char *fname);
+
+#define luaL_execresult COMPAT53_CONCAT(COMPAT53_PREFIX, L_execresult)
+COMPAT53_API int luaL_execresult (lua_State *L, int stat);
+
+#define lua_callk(L, na, nr, ctx, cont) \
+  ((void)(ctx), (void)(cont), lua_call((L), (na), (nr)))
+#define lua_pcallk(L, na, nr, err, ctx, cont) \
+  ((void)(ctx), (void)(cont), lua_pcall((L), (na), (nr), (err)))
+
+#define lua_resume(L, from, nargs) \
+  ((void)(from), lua_resume((L), (nargs)))
+
+#define luaL_buffinit COMPAT53_CONCAT(COMPAT53_PREFIX, _buffinit_53)
+COMPAT53_API void luaL_buffinit (lua_State *L, luaL_Buffer_53 *B);
+
+#define luaL_prepbuffsize COMPAT53_CONCAT(COMPAT53_PREFIX, _prepbufsize_53)
+COMPAT53_API char *luaL_prepbuffsize (luaL_Buffer_53 *B, size_t s);
+
+#define luaL_addlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _addlstring_53)
+COMPAT53_API void luaL_addlstring (luaL_Buffer_53 *B, const char *s, size_t l);
+
+#define luaL_addvalue COMPAT53_CONCAT(COMPAT53_PREFIX, _addvalue_53)
+COMPAT53_API void luaL_addvalue (luaL_Buffer_53 *B);
+
+#define luaL_pushresult COMPAT53_CONCAT(COMPAT53_PREFIX, _pushresult_53)
+COMPAT53_API void luaL_pushresult (luaL_Buffer_53 *B);
+
+#undef luaL_buffinitsize
+#define luaL_buffinitsize(L, B, s) \
+  (luaL_buffinit((L), (B)), luaL_prepbuffsize((B), (s)))
+
+#undef luaL_prepbuffer
+#define luaL_prepbuffer(B) \
+  luaL_prepbuffsize((B), LUAL_BUFFERSIZE)
+
+#undef luaL_addchar
+#define luaL_addchar(B, c) \
+  ((void)((B)->nelems < (B)->capacity || luaL_prepbuffsize((B), 1)), \
+   ((B)->ptr[(B)->nelems++] = (c)))
+
+#undef luaL_addsize
+#define luaL_addsize(B, s) \
+  ((B)->nelems += (s))
+
+#undef luaL_addstring
+#define luaL_addstring(B, s) \
+  luaL_addlstring((B), (s), strlen((s)))
+
+#undef luaL_pushresultsize
+#define luaL_pushresultsize(B, s) \
+  (luaL_addsize((B), (s)), luaL_pushresult((B)))
+
+#if defined(LUA_COMPAT_APIINTCASTS)
+#define lua_pushunsigned(L, n) \
+  lua_pushinteger((L), (lua_Integer)(n))
+#define lua_tounsignedx(L, i, is) \
+  ((lua_Unsigned)lua_tointegerx((L), (i), (is)))
+#define lua_tounsigned(L, i) \
+  lua_tounsignedx((L), (i), NULL)
+#define luaL_checkunsigned(L, a) \
+  ((lua_Unsigned)luaL_checkinteger((L), (a)))
+#define luaL_optunsigned(L, a, d) \
+  ((lua_Unsigned)luaL_optinteger((L), (a), (lua_Integer)(d)))
+#endif
+
+#endif /* Lua 5.1 only */
+
+
+
+/* declarations for Lua 5.1 and 5.2 */
+#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM <= 502
+
+typedef int lua_KContext;
+
+typedef int (*lua_KFunction)(lua_State *L, int status, lua_KContext ctx);
+
+#define lua_dump(L, w, d, s) \
+  ((void)(s), lua_dump((L), (w), (d)))
+
+#define lua_getfield(L, i, k) \
+  (lua_getfield((L), (i), (k)), lua_type((L), -1))
+
+#define lua_gettable(L, i) \
+  (lua_gettable((L), (i)), lua_type((L), -1))
+
+#define lua_geti COMPAT53_CONCAT(COMPAT53_PREFIX, _geti)
+COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i);
+
+#define lua_getextraspace COMPAT53_CONCAT(COMPAT53_PREFIX, _getextraspace)
+COMPAT53_API void *lua_getextraspace (lua_State *L);
+
+#define lua_isinteger COMPAT53_CONCAT(COMPAT53_PREFIX, _isinteger)
+COMPAT53_API int lua_isinteger (lua_State *L, int index);
+
+#define lua_tointegerx COMPAT53_CONCAT(COMPAT53_PREFIX, _tointegerx_53)
+COMPAT53_API lua_Integer lua_tointegerx (lua_State *L, int i, int *isnum);
+
+#define lua_numbertointeger(n, p) \
+  ((*(p) = (lua_Integer)(n)), 1)
+
+#define lua_rawget(L, i) \
+  (lua_rawget((L), (i)), lua_type((L), -1))
+
+#define lua_rawgeti(L, i, n) \
+  (lua_rawgeti((L), (i), (n)), lua_type((L), -1))
+
+#define lua_rotate COMPAT53_CONCAT(COMPAT53_PREFIX, _rotate)
+COMPAT53_API void lua_rotate (lua_State *L, int idx, int n);
+
+#define lua_seti COMPAT53_CONCAT(COMPAT53_PREFIX, _seti)
+COMPAT53_API void lua_seti (lua_State *L, int index, lua_Integer i);
+
+#define lua_stringtonumber COMPAT53_CONCAT(COMPAT53_PREFIX, _stringtonumber)
+COMPAT53_API size_t lua_stringtonumber (lua_State *L, const char *s);
+
+#define luaL_tolstring COMPAT53_CONCAT(COMPAT53_PREFIX, L_tolstring)
+COMPAT53_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len);
+
+#define luaL_getmetafield(L, o, e) \
+  (luaL_getmetafield((L), (o), (e)) ? lua_type((L), -1) : LUA_TNIL)
+
+#define luaL_newmetatable(L, tn) \
+  (luaL_newmetatable((L), (tn)) ? (lua_pushstring((L), (tn)), lua_setfield((L), -2, "__name"), 1) : 0)
+
+#define luaL_requiref COMPAT53_CONCAT(COMPAT53_PREFIX, L_requiref_53)
+COMPAT53_API void luaL_requiref (lua_State *L, const char *modname,
+                                 lua_CFunction openf, int glb );
+
+#endif /* Lua 5.1 and Lua 5.2 */
+
+
+
+/* declarations for Lua 5.2 */
+#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 502
+
+/* XXX not implemented:
+ * lua_isyieldable
+ * lua_arith (new operators)
+ * lua_pushfstring (new formats)
+ */
+
+#define lua_getglobal(L, n) \
+  (lua_getglobal((L), (n)), lua_type((L), -1))
+
+#define lua_getuservalue(L, i) \
+  (lua_getuservalue((L), (i)), lua_type((L), -1))
+
+#define lua_pushlstring(L, s, len) \
+  (((len) == 0) ? lua_pushlstring((L), "", 0) : lua_pushlstring((L), (s), (len)))
+
+#define lua_rawgetp(L, i, p) \
+  (lua_rawgetp((L), (i), (p)), lua_type((L), -1))
+
+#define LUA_KFUNCTION(_name) \
+  static int (_name)(lua_State *L, int status, lua_KContext ctx); \
+  static int (_name ## _52)(lua_State *L) { \
+    lua_KContext ctx; \
+    int status = lua_getctx(L, &ctx); \
+    return (_name)(L, status, ctx); \
+  } \
+  static int (_name)(lua_State *L, int status, lua_KContext ctx)
+
+#define lua_pcallk(L, na, nr, err, ctx, cont) \
+  lua_pcallk((L), (na), (nr), (err), (ctx), cont ## _52)
+
+#define lua_callk(L, na, nr, ctx, cont) \
+  lua_callk((L), (na), (nr), (ctx), cont ## _52)
+
+#define lua_yieldk(L, nr, ctx, cont) \
+  lua_yieldk((L), (nr), (ctx), cont ## _52)
+
+#ifdef lua_call
+#  undef lua_call
+#  define lua_call(L, na, nr) \
+  (lua_callk)((L), (na), (nr), 0, NULL)
+#endif
+
+#ifdef lua_pcall
+#  undef lua_pcall
+#  define lua_pcall(L, na, nr, err) \
+  (lua_pcallk)((L), (na), (nr), (err), 0, NULL)
+#endif
+
+#ifdef lua_yield
+#  undef lua_yield
+#  define lua_yield(L, nr) \
+  (lua_yieldk)((L), (nr), 0, NULL)
+#endif
+
+#endif /* Lua 5.2 only */
+
+
+
+/* other Lua versions */
+#if !defined(LUA_VERSION_NUM) || LUA_VERSION_NUM < 501 || LUA_VERSION_NUM > 504
+
+#  error "unsupported Lua version (i.e. not Lua 5.1, 5.2, 5.3, or 5.4)"
+
+#endif /* other Lua versions except 5.1, 5.2, 5.3, and 5.4 */
+
+
+
+/* helper macro for defining continuation functions (for every version
+ * *except* Lua 5.2) */
+#ifndef LUA_KFUNCTION
+#define LUA_KFUNCTION(_name) \
+  static int (_name)(lua_State *L, int status, lua_KContext ctx)
+#endif
+
+
+#if defined(COMPAT53_INCLUDE_SOURCE)
+#  include "compat-5.3.c"
+#endif
+
+
+#endif /* COMPAT53_H_ */
+

src/ffi/shim/shim.c

@@ -0,0 +1,509 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2019-2021 A. Orlenko
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#include <lauxlib.h>
+#include <lua.h>
+
+#include "compat-5.3.h"
+
+size_t MLUA_WRAPPED_ERROR_SIZE = 0;
+size_t MLUA_WRAPPED_PANIC_SIZE = 0;
+
+const void *MLUA_WRAPPED_ERROR_KEY = NULL;
+const void *MLUA_WRAPPED_PANIC_KEY = NULL;
+
+extern void wrapped_error_traceback(lua_State *L, int error_idx, void *error_ud,
+                                    int has_traceback);
+
+extern int mlua_hook_proc(lua_State *L, lua_Debug *ar);
+
+#define max(a, b) (a > b ? a : b)
+
+typedef struct {
+  const char *data;
+  size_t len;
+} StringArg;
+
+// A wrapper around Rust function to protect from triggering longjmp in Rust.
+// Rust callback expected to return -1 in case of errors or number of output
+// values.
+static int lua_call_rust(lua_State *L) {
+  int nargs = lua_gettop(L);
+
+  // We need one extra stack space to store preallocated memory, and at least 2
+  // stack spaces overall for handling error metatables in rust fn
+  int extra_stack = 1;
+  if (nargs < 2) {
+    extra_stack = 2 - nargs;
+  }
+
+  luaL_checkstack(L, extra_stack,
+                  "not enough stack space for callback error handling");
+
+  // We cannot shadow rust errors with Lua ones, we pre-allocate enough memory
+  // to store a wrapped error or panic *before* we proceed.
+  lua_newuserdata(L, max(MLUA_WRAPPED_ERROR_SIZE, MLUA_WRAPPED_PANIC_SIZE));
+  lua_rotate(L, 1, 1);
+
+  lua_CFunction rust_callback = lua_touserdata(L, lua_upvalueindex(1));
+
+  int ret = rust_callback(L);
+  if (ret == -1) {
+    lua_error(L);
+  }
+
+  return ret;
+}
+
+void lua_call_mlua_hook_proc(lua_State *L, lua_Debug *ar) {
+  luaL_checkstack(L, 2, "not enough stack space for callback error handling");
+  lua_newuserdata(L, max(MLUA_WRAPPED_ERROR_SIZE, MLUA_WRAPPED_PANIC_SIZE));
+  lua_rotate(L, 1, 1);
+  int ret = mlua_hook_proc(L, ar);
+  if (ret == -1) {
+    lua_error(L);
+  }
+}
+
+static inline lua_Integer lua_popinteger(lua_State *L) {
+  lua_Integer index = lua_tointeger(L, -1);
+  lua_pop(L, 1);
+  return index;
+}
+
+//
+// Common functions
+//
+
+int lua_gc_s(lua_State *L) {
+  int data = lua_popinteger(L);
+  int what = lua_popinteger(L);
+  int ret = lua_gc(L, what, data);
+  lua_pushinteger(L, ret);
+  return 1;
+}
+
+int luaL_ref_s(lua_State *L) {
+  int ret = luaL_ref(L, -2);
+  lua_pushinteger(L, ret);
+  return 1;
+}
+
+int lua_pushlstring_s(lua_State *L) {
+  StringArg *s = lua_touserdata(L, -1);
+  lua_pop(L, 1);
+  lua_pushlstring(L, s->data, s->len);
+  return 1;
+}
+
+int lua_tolstring_s(lua_State *L) {
+  void *len = lua_touserdata(L, -1);
+  lua_pop(L, 1);
+  const char *s = lua_tolstring(L, -1, len);
+  lua_pushlightuserdata(L, (void *)s);
+  return 2;
+}
+
+int lua_newthread_s(lua_State *L) {
+  lua_newthread(L);
+  return 1;
+}
+
+int lua_newuserdata_s(lua_State *L) {
+  size_t size = lua_tointeger(L, -1);
+  lua_pop(L, 1);
+  lua_newuserdata(L, size);
+  return 1;
+}
+
+int lua_newwrappederror_s(lua_State *L) {
+  lua_newuserdata(L, MLUA_WRAPPED_ERROR_SIZE);
+  return 1;
+}
+
+int lua_pushcclosure_s(lua_State *L) {
+  int n = lua_gettop(L) - 1;
+  lua_CFunction fn = lua_touserdata(L, -1);
+  lua_pop(L, 1);
+  lua_pushcclosure(L, fn, n);
+  return 1;
+}
+
+int lua_pushrclosure_s(lua_State *L) {
+  int n = lua_gettop(L);
+  lua_pushcclosure(L, lua_call_rust, n);
+  return 1;
+}
+
+int luaL_requiref_s(lua_State *L) {
+  const char *modname = lua_touserdata(L, -3);
+  lua_CFunction openf = lua_touserdata(L, -2);
+  int glb = lua_tointeger(L, -1);
+  lua_pop(L, 3);
+  luaL_requiref(L, modname, openf, glb);
+  return 1;
+}
+
+//
+// Table functions
+//
+
+int lua_newtable_s(lua_State *L) {
+  lua_createtable(L, 0, 0);
+  return 1;
+}
+
+int lua_createtable_s(lua_State *L) {
+  int nrec = lua_popinteger(L);
+  int narr = lua_popinteger(L);
+  lua_createtable(L, narr, nrec);
+  return 1;
+}
+
+int lua_gettable_s(lua_State *L) {
+  lua_gettable(L, -2);
+  return 1;
+}
+
+int lua_settable_s(lua_State *L) {
+  lua_settable(L, -3);
+  return 0;
+}
+
+int lua_geti_s(lua_State *L) {
+  lua_Integer index = lua_popinteger(L);
+  lua_geti(L, -1, index);
+  return 1;
+}
+
+int lua_rawset_s(lua_State *L) {
+  lua_rawset(L, -3);
+  return 0;
+}
+
+int lua_rawseti_s(lua_State *L) {
+  lua_Integer index = lua_popinteger(L);
+  lua_rawseti(L, -2, index);
+  return 0;
+}
+
+int lua_rawsetp_s(lua_State *L) {
+  void *p = lua_touserdata(L, -1);
+  lua_pop(L, 1);
+  lua_rawsetp(L, -2, p);
+  return 0;
+}
+
+int lua_rawsetfield_s(lua_State *L) {
+  StringArg *s = lua_touserdata(L, -2);
+  lua_pushlstring(L, s->data, s->len);
+  lua_replace(L, -3);
+  lua_rawset(L, -3);
+  return 0;
+}
+
+int lua_rawinsert_s(lua_State *L) {
+  lua_Integer index = lua_popinteger(L);
+  lua_Integer size = lua_rawlen(L, -2);
+
+  for (lua_Integer i = size; i >= index; i--) {
+    // table[i+1] = table[i]
+    lua_rawgeti(L, -2, i);
+    lua_rawseti(L, -3, i + 1);
+  }
+  lua_rawseti(L, -2, index);
+
+  return 0;
+}
+
+int lua_rawremove_s(lua_State *L) {
+  lua_Integer index = lua_popinteger(L);
+  lua_Integer size = lua_rawlen(L, -1);
+
+  for (lua_Integer i = index; i < size; i++) {
+    lua_rawgeti(L, -1, i + 1);
+    lua_rawseti(L, -2, i);
+  }
+  lua_pushnil(L);
+  lua_rawseti(L, -2, size);
+
+  return 0;
+}
+
+int luaL_len_s(lua_State *L) {
+  lua_pushinteger(L, luaL_len(L, -1));
+  return 1;
+}
+
+int lua_next_s(lua_State *L) {
+  int ret = lua_next(L, -2);
+  lua_pushinteger(L, ret);
+  return ret == 0 ? 1 : 3;
+}
+
+//
+// Moved from Rust to C
+//
+
+// Wrapper to lookup in `field_getters` first, then `methods`, ending
+// original `__index`. Used only if `field_getters` or `methods` set.
+int meta_index_impl(lua_State *state) {
+  // stack: self, key
+  luaL_checkstack(state, 2, NULL);
+
+  // lookup in `field_getters` table
+  if (lua_isnil(state, lua_upvalueindex(2)) == 0) {
+    lua_pushvalue(state, -1); // `key` arg
+    if (lua_rawget(state, lua_upvalueindex(2)) != LUA_TNIL) {
+      lua_insert(state, -3); // move function
+      lua_pop(state, 1);     // remove `key`
+      lua_call(state, 1, 1);
+      return 1;
+    }
+    lua_pop(state, 1); // pop the nil value
+  }
+  // lookup in `methods` table
+  if (lua_isnil(state, lua_upvalueindex(3)) == 0) {
+    lua_pushvalue(state, -1); // `key` arg
+    if (lua_rawget(state, lua_upvalueindex(3)) != LUA_TNIL) {
+      lua_insert(state, -3);
+      lua_pop(state, 2);
+      return 1;
+    }
+    lua_pop(state, 1); // pop the nil value
+  }
+
+  // lookup in `__index`
+  lua_pushvalue(state, lua_upvalueindex(1));
+  switch (lua_type(state, -1)) {
+  case LUA_TNIL:
+    lua_pop(state, 1); // pop the nil value
+    const char *field = lua_tostring(state, -1);
+    luaL_error(state, "attempt to get an unknown field '%s'", field);
+    break;
+
+  case LUA_TTABLE:
+    lua_insert(state, -2);
+    lua_gettable(state, -2);
+    break;
+
+  case LUA_TFUNCTION:
+    lua_insert(state, -3);
+    lua_call(state, 2, 1);
+    break;
+  }
+
+  return 1;
+}
+
+// Similar to `meta_index_impl`, checks `field_setters` table first, then
+// `__newindex` metamethod. Used only if `field_setters` set.
+int meta_newindex_impl(lua_State *state) {
+  // stack: self, key, value
+  luaL_checkstack(state, 2, NULL);
+
+  // lookup in `field_setters` table
+  lua_pushvalue(state, -2); // `key` arg
+  if (lua_rawget(state, lua_upvalueindex(2)) != LUA_TNIL) {
+    lua_remove(state, -3); // remove `key`
+    lua_insert(state, -3); // move function
+    lua_call(state, 2, 0);
+    return 0;
+  }
+  lua_pop(state, 1); // pop the nil value
+
+  // lookup in `__newindex`
+  lua_pushvalue(state, lua_upvalueindex(1));
+  switch (lua_type(state, -1)) {
+  case LUA_TNIL:
+    lua_pop(state, 1); // pop the nil value
+    const char *field = lua_tostring(state, -2);
+    luaL_error(state, "attempt to set an unknown field '%s'", field);
+    break;
+
+  case LUA_TTABLE:
+    lua_insert(state, -3);
+    lua_settable(state, -3);
+    break;
+
+  case LUA_TFUNCTION:
+    lua_insert(state, -4);
+    lua_call(state, 3, 0);
+    break;
+  }
+
+  return 0;
+}
+
+// See Function::bind
+int bind_call_impl(lua_State *state) {
+  int nargs = lua_gettop(state);
+  int nbinds = lua_tointeger(state, lua_upvalueindex(2));
+  luaL_checkstack(state, nbinds + 2, NULL);
+
+  lua_settop(state, nargs + nbinds + 1);
+  lua_rotate(state, -(nargs + nbinds + 1), nbinds + 1);
+
+  lua_pushvalue(state, lua_upvalueindex(1));
+  lua_replace(state, 1);
+
+  for (int i = 0; i < nbinds; i++) {
+    lua_pushvalue(state, lua_upvalueindex(i + 3));
+    lua_replace(state, i + 2);
+  }
+
+  lua_call(state, nargs + nbinds, LUA_MULTRET);
+  return lua_gettop(state);
+}
+
+// Returns 1 if a value at index `index` is a special wrapped struct identified
+// by `key`
+int is_wrapped_struct(lua_State *state, int index, const void *key) {
+  if (key == NULL) {
+    // Not yet initialized?
+    return 0;
+  }
+
+  void *ud = lua_touserdata(state, index);
+  if (ud == NULL || lua_getmetatable(state, index) == 0) {
+    return 0;
+  }
+  lua_rawgetp(state, LUA_REGISTRYINDEX, key);
+  int res = lua_rawequal(state, -1, -2);
+  lua_pop(state, 2);
+  return res;
+}
+
+// Takes an error at the top of the stack, and if it is a WrappedError, converts
+// it to an Error::CallbackError with a traceback, if it is some lua type,
+// prints the error along with a traceback, and if it is a WrappedPanic, does
+// not modify it. This function does its best to avoid triggering another error
+// and shadowing previous rust errors, but it may trigger Lua errors that shadow
+// rust errors under certain memory conditions. This function ensures that such
+// behavior will *never* occur with a rust panic, however.
+int error_traceback(lua_State *state) {
+  // I believe luaL_traceback < 5.4 requires this much free stack to not error.
+  // 5.4 uses luaL_Buffer
+  const int LUA_TRACEBACK_STACK = 11;
+
+  if (lua_checkstack(state, 2) == 0) {
+    // If we don't have enough stack space to even check the error type, do
+    // nothing so we don't risk shadowing a rust panic.
+    return 1;
+  }
+
+  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_ERROR_KEY) != 0) {
+    int error_idx = lua_absindex(state, -1);
+    // lua_newuserdata and luaL_traceback may error
+    void *error_ud = lua_newuserdata(state, MLUA_WRAPPED_ERROR_SIZE);
+    int has_traceback = 0;
+    if (lua_checkstack(state, LUA_TRACEBACK_STACK) != 0) {
+      luaL_traceback(state, state, NULL, 0);
+      has_traceback = 1;
+    }
+    wrapped_error_traceback(state, error_idx, error_ud, has_traceback);
+    return 1;
+  }
+
+  if (MLUA_WRAPPED_PANIC_KEY != NULL &&
+      !is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY) &&
+      lua_checkstack(state, LUA_TRACEBACK_STACK) != 0) {
+    const char *s = luaL_tolstring(state, -1, NULL);
+    luaL_traceback(state, state, s, 0);
+    lua_remove(state, -2);
+  }
+
+  return 1;
+}
+
+int error_traceback_s(lua_State *L) {
+  lua_State *L1 = lua_touserdata(L, -1);
+  lua_pop(L, 1);
+  return error_traceback(L1);
+}
+
+// A `pcall` implementation that does not allow Lua to catch Rust panics.
+// Instead, panics automatically resumed.
+int lua_nopanic_pcall(lua_State *state) {
+  luaL_checkstack(state, 2, NULL);
+
+  int top = lua_gettop(state);
+  if (top == 0) {
+    lua_pushstring(state, "not enough arguments to pcall");
+    lua_error(state);
+  }
+
+  if (lua_pcall(state, top - 1, LUA_MULTRET, 0) == LUA_OK) {
+    lua_pushboolean(state, 1);
+    lua_insert(state, 1);
+    return lua_gettop(state);
+  }
+
+  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY)) {
+    lua_error(state);
+  }
+  lua_pushboolean(state, 0);
+  lua_insert(state, -2);
+  return 2;
+}
+
+// A `xpcall` implementation that does not allow Lua to catch Rust panics.
+// Instead, panics automatically resumed.
+
+static int xpcall_msgh(lua_State *state) {
+  luaL_checkstack(state, 2, NULL);
+  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY)) {
+    return 1;
+  }
+  lua_pushvalue(state, lua_upvalueindex(1));
+  lua_insert(state, 1);
+  lua_call(state, lua_gettop(state) - 1, LUA_MULTRET);
+  return lua_gettop(state);
+}
+
+int lua_nopanic_xpcall(lua_State *state) {
+  luaL_checkstack(state, 2, NULL);
+
+  int top = lua_gettop(state);
+  if (top < 2) {
+    lua_pushstring(state, "not enough arguments to xpcall");
+    lua_error(state);
+  }
+
+  lua_pushvalue(state, 2);
+  lua_pushcclosure(state, xpcall_msgh, 1);
+  lua_copy(state, 1, 2);
+  lua_replace(state, 1);
+
+  if (lua_pcall(state, lua_gettop(state) - 2, LUA_MULTRET, 1) == LUA_OK) {
+    lua_pushboolean(state, 1);
+    lua_insert(state, 2);
+    return lua_gettop(state) - 1;
+  }
+
+  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY)) {
+    lua_error(state);
+  }
+  lua_pushboolean(state, 0);
+  lua_insert(state, -2);
+  return 2;
+}

src/function.rs

@@ -1,14 +1,15 @@
-use std::os::raw::c_int;
-use std::ptr;
+use std::os::raw::{c_int, c_void};
+use std::slice;
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::types::LuaRef;
-use crate::util::{
-    assert_stack, check_stack, error_traceback, pop_error, protect_lua_closure, StackGuard,
-};
+use crate::util::{assert_stack, check_stack, pop_error, StackGuard};
 use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
 
+#[cfg(feature = "async")]
+use {futures_core::future::LocalBoxFuture, futures_util::future};
+
 /// Handle to an internal Lua function.
 #[derive(Clone, Debug)]
 pub struct Function<'lua>(pub(crate) LuaRef<'lua>);
@@ -64,7 +65,7 @@ impl<'lua> Function<'lua> {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, nargs + 3)?;
 
-            ffi::lua_pushcfunction(lua.state, error_traceback);
+            ffi::lua_pushcfunction(lua.state, ffi::safe::error_traceback);
             let stack_start = ffi::lua_gettop(lua.state);
             lua.push_ref(&self.0);
             for arg in args {
@@ -86,6 +87,50 @@ impl<'lua> Function<'lua> {
         R::from_lua_multi(results, lua)
     }
 
+    /// Returns a Feature that, when polled, calls `self`, passing `args` as function arguments,
+    /// and drives the execution.
+    ///
+    /// Internaly it wraps the function to an [`AsyncThread`].
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::time::Duration;
+    /// use futures_timer::Delay;
+    /// # use mlua::{Lua, Result};
+    /// # #[tokio::main]
+    /// # async fn main() -> Result<()> {
+    /// # let lua = Lua::new();
+    ///
+    /// let sleep = lua.create_async_function(move |_lua, n: u64| async move {
+    ///     Delay::new(Duration::from_millis(n)).await;
+    ///     Ok(())
+    /// })?;
+    ///
+    /// sleep.call_async(10).await?;
+    ///
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`AsyncThread`]: struct.AsyncThread.html
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    pub fn call_async<'fut, A, R>(&self, args: A) -> LocalBoxFuture<'fut, Result<R>>
+    where
+        'lua: 'fut,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua> + 'fut,
+    {
+        let lua = self.0.lua;
+        match lua.create_thread(self.clone()) {
+            Ok(t) => Box::pin(t.into_async(args)),
+            Err(e) => Box::pin(future::err(e)),
+        }
+    }
+
     /// Returns a function that, when called, calls `self`, passing `args` as the first set of
     /// arguments.
     ///
@@ -114,26 +159,6 @@ impl<'lua> Function<'lua> {
     /// # }
     /// ```
     pub fn bind<A: ToLuaMulti<'lua>>(&self, args: A) -> Result<Function<'lua>> {
-        unsafe extern "C" fn bind_call_impl(state: *mut ffi::lua_State) -> c_int {
-            let nargs = ffi::lua_gettop(state);
-            let nbinds = ffi::lua_tointeger(state, ffi::lua_upvalueindex(2)) as c_int;
-            ffi::luaL_checkstack(state, nbinds + 2, ptr::null());
-
-            ffi::lua_settop(state, nargs + nbinds + 1);
-            ffi::lua_rotate(state, -(nargs + nbinds + 1), nbinds + 1);
-
-            ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
-            ffi::lua_replace(state, 1);
-
-            for i in 0..nbinds {
-                ffi::lua_pushvalue(state, ffi::lua_upvalueindex(i + 3));
-                ffi::lua_replace(state, i + 2);
-            }
-
-            ffi::lua_call(state, nargs + nbinds, ffi::LUA_MULTRET);
-            ffi::lua_gettop(state)
-        }
-
         let lua = self.0.lua;
 
         let args = args.to_lua_multi(lua)?;
@@ -146,19 +171,50 @@ impl<'lua> Function<'lua> {
         unsafe {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, nargs + 5)?;
+
             lua.push_ref(&self.0);
             ffi::lua_pushinteger(lua.state, nargs as ffi::lua_Integer);
             for arg in args {
                 lua.push_value(arg)?;
             }
-
-            protect_lua_closure(lua.state, nargs + 2, 1, |state| {
-                ffi::lua_pushcclosure(state, bind_call_impl, nargs + 2);
-            })?;
+            ffi::safe::lua_pushcclosure(lua.state, ffi::safe::bind_call_impl, nargs + 2)?;
 
             Ok(Function(lua.pop_ref()))
         }
     }
+
+    /// Dumps the function as a binary chunk.
+    ///
+    /// If `strip` is true, the binary representation may not include all debug information
+    /// about the function, to save space.
+    pub fn dump(&self, strip: bool) -> Vec<u8> {
+        unsafe extern "C" fn writer(
+            _state: *mut ffi::lua_State,
+            buf: *const c_void,
+            buf_len: usize,
+            data: *mut c_void,
+        ) -> c_int {
+            let data = &mut *(data as *mut Vec<u8>);
+            let buf = slice::from_raw_parts(buf as *const u8, buf_len);
+            data.extend_from_slice(buf);
+            0
+        }
+
+        let lua = self.0.lua;
+        let mut data: Vec<u8> = Vec::new();
+        unsafe {
+            let _sg = StackGuard::new(lua.state);
+            assert_stack(lua.state, 1);
+
+            lua.push_ref(&self.0);
+            let data_ptr = &mut data as *mut Vec<u8> as *mut c_void;
+            let strip = if strip { 1 } else { 0 };
+            ffi::lua_dump(lua.state, writer, data_ptr, strip);
+            ffi::lua_pop(lua.state, 1);
+        }
+
+        data
+    }
 }
 
 impl<'lua> PartialEq for Function<'lua> {

src/hook.rs

@@ -0,0 +1,196 @@
+use std::ffi::CStr;
+use std::marker::PhantomData;
+use std::os::raw::{c_char, c_int};
+
+use crate::ffi::{self, lua_Debug, lua_State};
+use crate::lua::Lua;
+use crate::util::callback_error;
+
+/// Contains information about currently executing Lua code.
+///
+/// The `Debug` structure is provided as a parameter to the hook function set with
+/// [`Lua::set_hook`]. You may call the methods on this structure to retrieve information about the
+/// Lua code executing at the time that the hook function was called. Further information can be
+/// found in the [Lua 5.3 documentaton][lua_doc].
+///
+/// [lua_doc]: https://www.lua.org/manual/5.3/manual.html#lua_Debug
+/// [`Lua::set_hook`]: struct.Lua.html#method.set_hook
+#[derive(Clone)]
+pub struct Debug<'a> {
+    ar: *mut lua_Debug,
+    state: *mut lua_State,
+    _phantom: PhantomData<&'a ()>,
+}
+
+impl<'a> Debug<'a> {
+    /// Corresponds to the `n` what mask.
+    pub fn names(&self) -> DebugNames<'a> {
+        unsafe {
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, cstr!("n"), self.ar) != 0,
+                "lua_getinfo failed with `n`"
+            );
+            DebugNames {
+                name: ptr_to_str((*self.ar).name),
+                name_what: ptr_to_str((*self.ar).namewhat),
+            }
+        }
+    }
+
+    /// Corresponds to the `S` what mask.
+    pub fn source(&self) -> DebugSource<'a> {
+        unsafe {
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, cstr!("S"), self.ar) != 0,
+                "lua_getinfo failed with `S`"
+            );
+            DebugSource {
+                source: ptr_to_str((*self.ar).source),
+                short_src: ptr_to_str((*self.ar).short_src.as_ptr()),
+                line_defined: (*self.ar).linedefined as i32,
+                last_line_defined: (*self.ar).lastlinedefined as i32,
+                what: ptr_to_str((*self.ar).what),
+            }
+        }
+    }
+
+    /// Corresponds to the `l` what mask. Returns the current line.
+    pub fn curr_line(&self) -> i32 {
+        unsafe {
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, cstr!("l"), self.ar) != 0,
+                "lua_getinfo failed with `l`"
+            );
+            (*self.ar).currentline as i32
+        }
+    }
+
+    /// Corresponds to the `t` what mask. Returns true if the hook is in a function tail call, false
+    /// otherwise.
+    pub fn is_tail_call(&self) -> bool {
+        unsafe {
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, cstr!("t"), self.ar) != 0,
+                "lua_getinfo failed with `t`"
+            );
+            (*self.ar).currentline != 0
+        }
+    }
+
+    /// Corresponds to the `u` what mask.
+    pub fn stack(&self) -> DebugStack {
+        unsafe {
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, cstr!("u"), self.ar) != 0,
+                "lua_getinfo failed with `u`"
+            );
+            DebugStack {
+                num_ups: (*self.ar).nups as i32,
+                #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+                num_params: (*self.ar).nparams as i32,
+                #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+                is_vararg: (*self.ar).isvararg != 0,
+            }
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct DebugNames<'a> {
+    pub name: Option<&'a [u8]>,
+    pub name_what: Option<&'a [u8]>,
+}
+
+#[derive(Clone, Debug)]
+pub struct DebugSource<'a> {
+    pub source: Option<&'a [u8]>,
+    pub short_src: Option<&'a [u8]>,
+    pub line_defined: i32,
+    pub last_line_defined: i32,
+    pub what: Option<&'a [u8]>,
+}
+
+#[derive(Copy, Clone, Debug)]
+pub struct DebugStack {
+    pub num_ups: i32,
+    /// Requires `feature = "lua54/lua53/lua52"`
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", doc))]
+    pub num_params: i32,
+    /// Requires `feature = "lua54/lua53/lua52"`
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", doc))]
+    pub is_vararg: bool,
+}
+
+/// Determines when a hook function will be called by Lua.
+#[derive(Clone, Copy, Debug, Default)]
+pub struct HookTriggers {
+    /// Before a function call.
+    pub on_calls: bool,
+    /// When Lua returns from a function.
+    pub on_returns: bool,
+    /// Before executing a new line, or returning from a function call.
+    pub every_line: bool,
+    /// After a certain number of VM instructions have been executed. When set to `Some(count)`,
+    /// `count` is the number of VM instructions to execute before calling the hook.
+    ///
+    /// # Performance
+    ///
+    /// Setting this option to a low value can incur a very high overhead.
+    pub every_nth_instruction: Option<u32>,
+}
+
+impl HookTriggers {
+    // Compute the mask to pass to `lua_sethook`.
+    pub(crate) fn mask(&self) -> c_int {
+        let mut mask: c_int = 0;
+        if self.on_calls {
+            mask |= ffi::LUA_MASKCALL
+        }
+        if self.on_returns {
+            mask |= ffi::LUA_MASKRET
+        }
+        if self.every_line {
+            mask |= ffi::LUA_MASKLINE
+        }
+        if self.every_nth_instruction.is_some() {
+            mask |= ffi::LUA_MASKCOUNT
+        }
+        mask
+    }
+
+    // Returns the `count` parameter to pass to `lua_sethook`, if applicable. Otherwise, zero is
+    // returned.
+    pub(crate) fn count(&self) -> c_int {
+        self.every_nth_instruction.unwrap_or(0) as c_int
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn mlua_hook_proc(state: *mut lua_State, ar: *mut lua_Debug) -> c_int {
+    callback_error(state, |_| {
+        let debug = Debug {
+            ar,
+            state,
+            _phantom: PhantomData,
+        };
+
+        let lua = Lua::make_from_ptr(state);
+        let hook_cb = mlua_expect!(lua.hook_callback(), "no hook callback set in hook_proc");
+
+        #[allow(clippy::match_wild_err_arm)]
+        match hook_cb.try_borrow_mut() {
+            Ok(mut b) => (&mut *b)(&lua, debug),
+            Err(_) => mlua_panic!("Lua should not allow hooks to be called within another hook"),
+        }?;
+
+        Ok(0)
+    })
+}
+
+unsafe fn ptr_to_str<'a>(input: *const c_char) -> Option<&'a [u8]> {
+    if input.is_null() {
+        None
+    } else {
+        Some(CStr::from_ptr(input).to_bytes())
+    }
+}

src/lib.rs

@@ -23,22 +23,60 @@
 //!
 //! The [`UserData`] trait can be implemented by user-defined types to make them available to Lua.
 //! Methods and operators to be used from Lua can be added using the [`UserDataMethods`] API.
+//! Fields are supported using the [`UserDataFields`] API.
+//!
+//! # Serde support
+//!
+//! The [`LuaSerdeExt`] trait implemented for [`Lua`] allows conversion from Rust types to Lua values
+//! and vice versa using serde. Any user defined data type that implements [`serde::Serialize`] or
+//! [`serde::Deserialize`] can be converted.
+//! For convenience, additional functionality to handle `NULL` values and arrays is provided.
+//!
+//! The [`Value`] enum implements [`serde::Serialize`] trait to support serializing Lua values
+//! (including [`UserData`]) into Rust values.
+//!
+//! Requires `feature = "serialize"`.
+//!
+//! # Async/await support
+//!
+//! The [`create_async_function`] allows creating non-blocking functions that returns [`Future`].
+//! Lua code with async capabilities can be executed by [`call_async`] family of functions or polling
+//! [`AsyncThread`] using any runtime (eg. Tokio).
+//!
+//! Requires `feature = "async"`.
+//!
+//! # `Send` requirement
+//! By default `mlua` is `!Send`. This can be changed by enabling `feature = "send"` that adds `Send` requirement
+//! to [`Function`]s and [`UserData`].
 //!
 //! [Lua programming language]: https://www.lua.org/
 //! [`Lua`]: struct.Lua.html
-//! [executing]: struct.Lua.html#method.exec
-//! [evaluating]: struct.Lua.html#method.eval
+//! [executing]: struct.Chunk.html#method.exec
+//! [evaluating]: struct.Chunk.html#method.eval
 //! [globals]: struct.Lua.html#method.globals
 //! [`ToLua`]: trait.ToLua.html
 //! [`FromLua`]: trait.FromLua.html
 //! [`ToLuaMulti`]: trait.ToLuaMulti.html
 //! [`FromLuaMulti`]: trait.FromLuaMulti.html
+//! [`Function`]: struct.Function.html
 //! [`UserData`]: trait.UserData.html
+//! [`UserDataFields`]: trait.UserDataFields.html
 //! [`UserDataMethods`]: trait.UserDataMethods.html
+//! [`LuaSerdeExt`]: serde/trait.LuaSerdeExt.html
+//! [`Value`]: enum.Value.html
+//! [`create_async_function`]: struct.Lua.html#method.create_async_function
+//! [`call_async`]: struct.Function.html#method.call_async
+//! [`AsyncThread`]: struct.AsyncThread.html
+//! [`Future`]: ../futures_core/future/trait.Future.html
+//! [`serde::Serialize`]: https://docs.serde.rs/serde/ser/trait.Serialize.html
+//! [`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
 
+// mlua types in rustdoc of other crates get linked to here.
+#![doc(html_root_url = "https://docs.rs/mlua/0.6.0-beta.1")]
 // Deny warnings inside doc tests / examples. When this isn't present, rustdoc doesn't show *any*
 // warnings at all.
 #![doc(test(attr(deny(warnings))))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 
 #[macro_use]
 mod macros;
@@ -47,6 +85,7 @@ mod conversion;
 mod error;
 mod ffi;
 mod function;
+mod hook;
 mod lua;
 mod multi;
 mod scope;
@@ -63,15 +102,35 @@ pub use crate::ffi::lua_State;
 
 pub use crate::error::{Error, ExternalError, ExternalResult, Result};
 pub use crate::function::Function;
-pub use crate::lua::{Chunk, Lua};
+pub use crate::hook::{Debug, DebugNames, DebugSource, DebugStack, HookTriggers};
+pub use crate::lua::{Chunk, ChunkMode, GCMode, Lua, LuaOptions};
 pub use crate::multi::Variadic;
 pub use crate::scope::Scope;
 pub use crate::stdlib::StdLib;
 pub use crate::string::String;
-pub use crate::table::{Table, TablePairs, TableSequence};
+pub use crate::table::{Table, TableExt, TablePairs, TableSequence};
 pub use crate::thread::{Thread, ThreadStatus};
 pub use crate::types::{Integer, LightUserData, Number, RegistryKey};
-pub use crate::userdata::{AnyUserData, MetaMethod, UserData, UserDataMethods};
+pub use crate::userdata::{AnyUserData, MetaMethod, UserData, UserDataFields, UserDataMethods};
 pub use crate::value::{FromLua, FromLuaMulti, MultiValue, Nil, ToLua, ToLuaMulti, Value};
 
+#[cfg(feature = "async")]
+pub use crate::thread::AsyncThread;
+
+#[cfg(feature = "serialize")]
+#[doc(inline)]
+pub use crate::serde::{ser::Options as SerializeOptions, LuaSerdeExt};
+
 pub mod prelude;
+#[cfg(feature = "serialize")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serialize")))]
+pub mod serde;
+
+// Re-export #[mlua_derive::lua_module].
+#[cfg(feature = "mlua_derive")]
+#[allow(unused_imports)]
+#[macro_use]
+extern crate mlua_derive;
+#[cfg(feature = "mlua_derive")]
+#[doc(hidden)]
+pub use mlua_derive::*;

src/macros.rs

@@ -78,3 +78,19 @@ macro_rules! mlua_expect {
         mlua_expect!($res, $msg)
     };
 }
+
+#[cfg(feature = "module")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! require_module_feature {
+    () => {};
+}
+
+#[cfg(not(feature = "module"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! require_module_feature {
+    () => {
+        compile_error!("Feature `module` must be enabled in the `mlua` crate");
+    };
+}

src/multi.rs

@@ -34,7 +34,7 @@ impl<'lua, T: ToLua<'lua>> ToLuaMulti<'lua> for T {
 
 impl<'lua, T: FromLua<'lua>> FromLuaMulti<'lua> for T {
     fn from_lua_multi(mut values: MultiValue<'lua>, lua: &'lua Lua) -> Result<Self> {
-        Ok(T::from_lua(values.pop_front().unwrap_or(Nil), lua)?)
+        T::from_lua(values.pop_front().unwrap_or(Nil), lua)
     }
 }
 
@@ -146,7 +146,7 @@ macro_rules! impl_tuple {
         }
 
         impl<'lua> FromLuaMulti<'lua> for () {
-            fn from_lua_multi(_: MultiValue, _: &'lua Lua) -> Result<Self> {
+            fn from_lua_multi(_: MultiValue<'lua>, _: &'lua Lua) -> Result<Self> {
                 Ok(())
             }
         }

src/prelude.rs

@@ -3,10 +3,18 @@
 pub use crate::{
     AnyUserData as LuaAnyUserData, Chunk as LuaChunk, Error as LuaError,
     ExternalError as LuaExternalError, ExternalResult as LuaExternalResult, FromLua, FromLuaMulti,
-    Function as LuaFunction, Integer as LuaInteger, LightUserData as LuaLightUserData, Lua,
-    MetaMethod as LuaMetaMethod, MultiValue as LuaMultiValue, Nil as LuaNil, Number as LuaNumber,
-    RegistryKey as LuaRegistryKey, Result as LuaResult, Scope as LuaScope, String as LuaString,
-    Table as LuaTable, TablePairs as LuaTablePairs, TableSequence as LuaTableSequence,
-    Thread as LuaThread, ThreadStatus as LuaThreadStatus, ToLua, ToLuaMulti,
-    UserData as LuaUserData, UserDataMethods as LuaUserDataMethods, Value as LuaValue,
+    Function as LuaFunction, GCMode as LuaGCMode, Integer as LuaInteger,
+    LightUserData as LuaLightUserData, Lua, LuaOptions, MetaMethod as LuaMetaMethod,
+    MultiValue as LuaMultiValue, Nil as LuaNil, Number as LuaNumber, RegistryKey as LuaRegistryKey,
+    Result as LuaResult, String as LuaString, Table as LuaTable, TableExt as LuaTableExt,
+    TablePairs as LuaTablePairs, TableSequence as LuaTableSequence, Thread as LuaThread,
+    ThreadStatus as LuaThreadStatus, ToLua, ToLuaMulti, UserData as LuaUserData,
+    UserDataMethods as LuaUserDataMethods, Value as LuaValue,
 };
+
+#[cfg(feature = "async")]
+pub use crate::AsyncThread as LuaAsyncThread;
+
+#[cfg(feature = "serialize")]
+#[doc(inline)]
+pub use crate::{LuaSerdeExt, SerializeOptions as LuaSerializeOptions};

src/scope.rs

@@ -1,22 +1,32 @@
 use std::any::Any;
-use std::cell::Cell;
-use std::cell::RefCell;
+use std::cell::{Cell, Ref, RefCell, RefMut};
 use std::marker::PhantomData;
 use std::mem;
-use std::os::raw::c_void;
-use std::rc::Rc;
+use std::os::raw::{c_int, c_void};
+
+#[cfg(feature = "serialize")]
+use serde::Serialize;
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::function::Function;
 use crate::lua::Lua;
-use crate::types::{Callback, LuaRef};
-use crate::userdata::{AnyUserData, MetaMethod, UserData, UserDataMethods};
-use crate::util::{
-    assert_stack, init_userdata_metatable, protect_lua_closure, push_string, push_userdata,
-    take_userdata, StackGuard,
+use crate::types::{Callback, LuaRef, MaybeSend};
+use crate::userdata::{
+    AnyUserData, MetaMethod, UserData, UserDataCell, UserDataFields, UserDataMethods,
+};
+use crate::util::{
+    assert_stack, check_stack, get_userdata, init_userdata_metatable, push_userdata, take_userdata,
+    StackGuard,
+};
+use crate::value::{FromLua, FromLuaMulti, MultiValue, ToLua, ToLuaMulti, Value};
+
+#[cfg(feature = "async")]
+use {
+    crate::types::AsyncCallback,
+    futures_core::future::{Future, LocalBoxFuture},
+    futures_util::future::{self, TryFutureExt},
 };
-use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti, Value};
 
 /// Constructed by the [`Lua::scope`] method, allows temporarily creating Lua userdata and
 /// callbacks that are not required to be Send or 'static.
@@ -26,10 +36,12 @@ use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti, Value};
 /// [`Lua::scope`]: struct.Lua.html#method.scope
 pub struct Scope<'lua, 'scope> {
     lua: &'lua Lua,
-    destructors: RefCell<Vec<(LuaRef<'lua>, fn(LuaRef<'lua>) -> Box<dyn Any>)>>,
+    destructors: RefCell<Vec<(LuaRef<'lua>, DestructorCallback<'lua>)>>,
     _scope_invariant: PhantomData<Cell<&'scope ()>>,
 }
 
+type DestructorCallback<'lua> = Box<dyn Fn(LuaRef<'lua>) -> Vec<Box<dyn Any>> + 'lua>;
+
 impl<'lua, 'scope> Scope<'lua, 'scope> {
     pub(crate) fn new(lua: &'lua Lua) -> Scope<'lua, 'scope> {
         Scope {
@@ -42,7 +54,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
     /// Wraps a Rust function or closure, creating a callable Lua function handle to it.
     ///
     /// This is a version of [`Lua::create_function`] that creates a callback which expires on
-    /// scope drop.  See [`Lua::scope`] for more details.
+    /// scope drop. See [`Lua::scope`] for more details.
     ///
     /// [`Lua::create_function`]: struct.Lua.html#method.create_function
     /// [`Lua::scope`]: struct.Lua.html#method.scope
@@ -54,7 +66,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
     {
         // Safe, because 'scope must outlive 'callback (due to Self containing 'scope), however the
         // callback itself must be 'scope lifetime, so the function should not be able to capture
-        // anything of 'callback lifetime.  'scope can't be shortened due to being invariant, and
+        // anything of 'callback lifetime. 'scope can't be shortened due to being invariant, and
         // the 'callback lifetime here can't be enlarged due to coming from a universal
         // quantification in Lua::scope.
         //
@@ -71,7 +83,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
     /// Wraps a Rust mutable closure, creating a callable Lua function handle to it.
     ///
     /// This is a version of [`Lua::create_function_mut`] that creates a callback which expires
-    /// on scope drop.  See [`Lua::scope`] and [`Scope::create_function`] for more details.
+    /// on scope drop. See [`Lua::scope`] and [`Scope::create_function`] for more details.
     ///
     /// [`Lua::create_function_mut`]: struct.Lua.html#method.create_function_mut
     /// [`Lua::scope`]: struct.Lua.html#method.scope
@@ -93,31 +105,109 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
         })
     }
 
+    /// Wraps a Rust async function or closure, creating a callable Lua function handle to it.
+    ///
+    /// This is a version of [`Lua::create_async_function`] that creates a callback which expires on
+    /// scope drop. See [`Lua::scope`] and [`Lua::async_scope`] for more details.
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// [`Lua::create_async_function`]: struct.Lua.html#method.create_async_function
+    /// [`Lua::scope`]: struct.Lua.html#method.scope
+    /// [`Lua::async_scope`]: struct.Lua.html#method.async_scope
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    pub fn create_async_function<'callback, A, R, F, FR>(
+        &'callback self,
+        func: F,
+    ) -> Result<Function<'lua>>
+    where
+        A: FromLuaMulti<'callback>,
+        R: ToLuaMulti<'callback>,
+        F: 'scope + Fn(&'callback Lua, A) -> FR,
+        FR: 'callback + Future<Output = Result<R>>,
+    {
+        unsafe {
+            self.create_async_callback(Box::new(move |lua, args| {
+                let args = match A::from_lua_multi(args, lua) {
+                    Ok(args) => args,
+                    Err(e) => return Box::pin(future::err(e)),
+                };
+                Box::pin(func(lua, args).and_then(move |ret| future::ready(ret.to_lua_multi(lua))))
+            }))
+        }
+    }
+
     /// Create a Lua userdata object from a custom userdata type.
     ///
     /// This is a version of [`Lua::create_userdata`] that creates a userdata which expires on
     /// scope drop, and does not require that the userdata type be Send (but still requires that the
-    /// UserData be 'static).  See [`Lua::scope`] for more details.
+    /// UserData be 'static).
+    /// See [`Lua::scope`] for more details.
     ///
     /// [`Lua::create_userdata`]: struct.Lua.html#method.create_userdata
     /// [`Lua::scope`]: struct.Lua.html#method.scope
-    pub fn create_static_userdata<T>(&self, data: T) -> Result<AnyUserData<'lua>>
+    pub fn create_userdata<T>(&self, data: T) -> Result<AnyUserData<'lua>>
+    where
+        T: 'static + UserData,
+    {
+        self.create_userdata_inner(UserDataCell::new(data))
+    }
+
+    /// Create a Lua userdata object from a custom serializable userdata type.
+    ///
+    /// This is a version of [`Lua::create_ser_userdata`] that creates a userdata which expires on
+    /// scope drop, and does not require that the userdata type be Send (but still requires that the
+    /// UserData be 'static).
+    /// See [`Lua::scope`] for more details.
+    ///
+    /// Requires `feature = "serialize"`
+    ///
+    /// [`Lua::create_ser_userdata`]: struct.Lua.html#method.create_ser_userdata
+    /// [`Lua::scope`]: struct.Lua.html#method.scope
+    #[cfg(feature = "serialize")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "serialize")))]
+    pub fn create_ser_userdata<T>(&self, data: T) -> Result<AnyUserData<'lua>>
+    where
+        T: 'static + UserData + Serialize,
+    {
+        self.create_userdata_inner(UserDataCell::new_ser(data))
+    }
+
+    fn create_userdata_inner<T>(&self, data: UserDataCell<T>) -> Result<AnyUserData<'lua>>
     where
         T: 'static + UserData,
     {
         // Safe even though T may not be Send, because the parent Lua cannot be sent to another
         // thread while the Scope is alive (or the returned AnyUserData handle even).
         unsafe {
-            let u = self.lua.make_userdata(data)?;
-            self.destructors.borrow_mut().push((u.0.clone(), |u| {
-                let state = u.lua.state;
+            let ud = self.lua.make_userdata(data)?;
+
+            #[cfg(any(feature = "lua51", feature = "luajit"))]
+            let newtable = self.lua.create_table()?;
+            let destructor: DestructorCallback = Box::new(move |ud| {
+                let state = ud.lua.state;
+                let _sg = StackGuard::new(state);
                 assert_stack(state, 2);
-                u.lua.push_ref(&u);
-                // We know the destructor has not run yet because we hold a reference to the
-                // userdata.
-                Box::new(take_userdata::<RefCell<T>>(state))
-            }));
-            Ok(u)
+
+                ud.lua.push_ref(&ud);
+
+                // We know the destructor has not run yet because we hold a reference to the userdata.
+
+                // Clear uservalue
+                #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+                ffi::lua_pushnil(state);
+                #[cfg(any(feature = "lua51", feature = "luajit"))]
+                ud.lua.push_ref(&newtable.0);
+                ffi::lua_setuservalue(state, -2);
+
+                vec![Box::new(take_userdata::<UserDataCell<T>>(state))]
+            });
+            self.destructors
+                .borrow_mut()
+                .push((ud.0.clone(), destructor));
+
+            Ok(ud)
         }
     }
 
@@ -129,18 +219,18 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
     ///
     /// Lifting the requirement that the UserData type be 'static comes with some important
     /// limitations, so if you only need to eliminate the Send requirement, it is probably better to
-    /// use [`Scope::create_static_userdata`] instead.
+    /// use [`Scope::create_userdata`] instead.
     ///
     /// The main limitation that comes from using non-'static userdata is that the produced userdata
     /// will no longer have a `TypeId` associated with it, becuase `TypeId` can only work for
-    /// 'static types.  This means that it is impossible, once the userdata is created, to get a
-    /// reference to it back *out* of an `AnyUserData` handle.  This also implies that the
+    /// 'static types. This means that it is impossible, once the userdata is created, to get a
+    /// reference to it back *out* of an `AnyUserData` handle. This also implies that the
     /// "function" type methods that can be added via [`UserDataMethods`] (the ones that accept
-    /// `AnyUserData` as a first parameter) are vastly less useful.  Also, there is no way to re-use
+    /// `AnyUserData` as a first parameter) are vastly less useful. Also, there is no way to re-use
     /// a single metatable for multiple non-'static types, so there is a higher cost associated with
     /// creating the userdata metatable each time a new userdata is created.
     ///
-    /// [`create_static_userdata`]: #method.create_static_userdata
+    /// [`Scope::create_userdata`]: #method.create_userdata
     /// [`Lua::create_userdata`]: struct.Lua.html#method.create_userdata
     /// [`Lua::scope`]: struct.Lua.html#method.scope
     /// [`UserDataMethods`]: trait.UserDataMethods.html
@@ -148,57 +238,47 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
     where
         T: 'scope + UserData,
     {
-        let data = Rc::new(RefCell::new(data));
+        let data = UserDataCell::new_arc(data);
 
         // 'callback outliving 'scope is a lie to make the types work out, required due to the
         // inability to work with the more correct callback type that is universally quantified over
-        // 'lua.  This is safe though, because `UserData::add_methods` does not get to pick the 'lua
+        // 'lua. This is safe though, because `UserData::add_methods` does not get to pick the 'lua
         // lifetime, so none of the static methods UserData types can add can possibly capture
         // parameters.
         fn wrap_method<'scope, 'lua, 'callback: 'scope, T: 'scope>(
             scope: &Scope<'lua, 'scope>,
-            data: Rc<RefCell<T>>,
+            data: UserDataCell<T>,
+            data_ptr: *mut c_void,
             method: NonStaticMethod<'callback, T>,
         ) -> Result<Function<'lua>> {
             // On methods that actually receive the userdata, we fake a type check on the passed in
             // userdata, where we pretend there is a unique type per call to
-            // `Scope::create_nonstatic_userdata`.  You can grab a method from a userdata and call
+            // `Scope::create_nonstatic_userdata`. You can grab a method from a userdata and call
             // it on a mismatched userdata type, which when using normal 'static userdata will fail
             // with a type mismatch, but here without this check would proceed as though you had
             // called the method on the original value (since we otherwise completely ignore the
             // first argument).
-            let check_data = data.clone();
             let check_ud_type = move |lua: &'callback Lua, value| {
-                if let Some(value) = value {
-                    if let Value::UserData(u) = value {
-                        unsafe {
-                            assert_stack(lua.state, 1);
-                            lua.push_ref(&u.0);
-                            ffi::lua_getuservalue(lua.state, -1);
-                            #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
-                            {
-                                ffi::lua_pushinteger(lua.state, 1);
-                                ffi::lua_gettable(lua.state, -2);
-                                ffi::lua_remove(lua.state, -2);
-                            }
-                            return ffi::lua_touserdata(lua.state, -1)
-                                == check_data.as_ptr() as *mut c_void;
+                if let Some(Value::UserData(ud)) = value {
+                    unsafe {
+                        let _sg = StackGuard::new(lua.state);
+                        check_stack(lua.state, 3)?;
+                        lua.push_userdata_ref(&ud.0)?;
+                        if get_userdata(lua.state, -1) == data_ptr {
+                            return Ok(());
                         }
                     }
-                }
-
-                false
+                };
+                Err(Error::UserDataTypeMismatch)
             };
 
             match method {
                 NonStaticMethod::Method(method) => {
-                    let method_data = data.clone();
                     let f = Box::new(move |lua, mut args: MultiValue<'callback>| {
-                        if !check_ud_type(lua, args.pop_front()) {
-                            return Err(Error::UserDataTypeMismatch);
-                        }
-                        let data = method_data
+                        check_ud_type(lua, args.pop_front())?;
+                        let data = data
                             .try_borrow()
+                            .map(|cell| Ref::map(cell, AsRef::as_ref))
                             .map_err(|_| Error::UserDataBorrowError)?;
                         method(lua, &*data, args)
                     });
@@ -206,16 +286,14 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
                 }
                 NonStaticMethod::MethodMut(method) => {
                     let method = RefCell::new(method);
-                    let method_data = data.clone();
                     let f = Box::new(move |lua, mut args: MultiValue<'callback>| {
-                        if !check_ud_type(lua, args.pop_front()) {
-                            return Err(Error::UserDataTypeMismatch);
-                        }
+                        check_ud_type(lua, args.pop_front())?;
                         let mut method = method
                             .try_borrow_mut()
                             .map_err(|_| Error::RecursiveMutCallback)?;
-                        let mut data = method_data
+                        let mut data = data
                             .try_borrow_mut()
+                            .map(|cell| RefMut::map(cell, AsMut::as_mut))
                             .map_err(|_| Error::UserDataBorrowMutError)?;
                         (&mut *method)(lua, &mut *data, args)
                     });
@@ -236,68 +314,133 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             }
         }
 
+        let mut ud_fields = NonStaticUserDataFields::default();
         let mut ud_methods = NonStaticUserDataMethods::default();
+        T::add_fields(&mut ud_fields);
         T::add_methods(&mut ud_methods);
 
         unsafe {
             let lua = self.lua;
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 6);
+            check_stack(lua.state, 13)?;
 
-            push_userdata(lua.state, ())?;
-            #[cfg(feature = "lua53")]
-            ffi::lua_pushlightuserdata(lua.state, data.as_ptr() as *mut c_void);
-            #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
-            protect_lua_closure(lua.state, 0, 1, |state| {
-                // Lua 5.2/5.1 allows to store only table. Then we will wrap the value.
-                ffi::lua_createtable(state, 1, 0);
-                ffi::lua_pushinteger(state, 1);
-                ffi::lua_pushlightuserdata(state, data.as_ptr() as *mut c_void);
-                ffi::lua_settable(state, -3);
-            })?;
-            ffi::lua_setuservalue(lua.state, -2);
+            push_userdata(lua.state, data.clone())?;
+            let data_ptr = ffi::lua_touserdata(lua.state, -1);
 
-            protect_lua_closure(lua.state, 0, 1, move |state| {
-                ffi::lua_newtable(state);
-            })?;
+            // Prepare metatable, add meta methods first and then meta fields
+            let meta_methods_nrec = ud_methods.meta_methods.len() + ud_fields.meta_fields.len() + 1;
+            ffi::safe::lua_createtable(lua.state, 0, meta_methods_nrec as c_int)?;
 
             for (k, m) in ud_methods.meta_methods {
-                push_string(lua.state, k.name())?;
-                lua.push_value(Value::Function(wrap_method(self, data.clone(), m)?))?;
+                let data = data.clone();
+                lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
+                ffi::safe::lua_rawsetfield(lua.state, -2, k.validate()?.name())?;
+            }
+            for (k, f) in ud_fields.meta_fields {
+                lua.push_value(f(mem::transmute(lua))?)?;
+                ffi::safe::lua_rawsetfield(lua.state, -2, k.validate()?.name())?;
+            }
+            let metatable_index = ffi::lua_absindex(lua.state, -1);
 
-                protect_lua_closure(lua.state, 3, 1, |state| {
-                    ffi::lua_rawset(state, -3);
-                })?;
+            let mut field_getters_index = None;
+            let field_getters_nrec = ud_fields.field_getters.len();
+            if field_getters_nrec > 0 {
+                ffi::safe::lua_createtable(lua.state, 0, field_getters_nrec as c_int)?;
+                for (k, m) in ud_fields.field_getters {
+                    let data = data.clone();
+                    lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
+                    ffi::safe::lua_rawsetfield(lua.state, -2, &k)?;
+                }
+                field_getters_index = Some(ffi::lua_absindex(lua.state, -1));
             }
 
-            if ud_methods.methods.is_empty() {
-                init_userdata_metatable::<()>(lua.state, -1, None)?;
-            } else {
-                protect_lua_closure(lua.state, 0, 1, |state| {
-                    ffi::lua_newtable(state);
-                })?;
+            let mut field_setters_index = None;
+            let field_setters_nrec = ud_fields.field_setters.len();
+            if field_setters_nrec > 0 {
+                ffi::safe::lua_createtable(lua.state, 0, field_setters_nrec as c_int)?;
+                for (k, m) in ud_fields.field_setters {
+                    let data = data.clone();
+                    lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
+                    ffi::safe::lua_rawsetfield(lua.state, -2, &k)?;
+                }
+                field_setters_index = Some(ffi::lua_absindex(lua.state, -1));
+            }
+
+            let mut methods_index = None;
+            let methods_nrec = ud_methods.methods.len();
+            if methods_nrec > 0 {
+                // Create table used for methods lookup
+                ffi::safe::lua_createtable(lua.state, 0, methods_nrec as c_int)?;
                 for (k, m) in ud_methods.methods {
-                    push_string(lua.state, &k)?;
-                    lua.push_value(Value::Function(wrap_method(self, data.clone(), m)?))?;
-                    protect_lua_closure(lua.state, 3, 1, |state| {
-                        ffi::lua_rawset(state, -3);
-                    })?;
+                    let data = data.clone();
+                    lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
+                    ffi::safe::lua_rawsetfield(lua.state, -2, &k)?;
+                }
+                methods_index = Some(ffi::lua_absindex(lua.state, -1));
+            }
+
+            init_userdata_metatable::<()>(
+                lua.state,
+                metatable_index,
+                field_getters_index,
+                field_setters_index,
+                methods_index,
+            )?;
+
+            let count = field_getters_index.map(|_| 1).unwrap_or(0)
+                + field_setters_index.map(|_| 1).unwrap_or(0)
+                + methods_index.map(|_| 1).unwrap_or(0);
+            ffi::lua_pop(lua.state, count);
+
+            let mt_id = ffi::lua_topointer(lua.state, -1);
+            ffi::lua_setmetatable(lua.state, -2);
+            let ud = AnyUserData(lua.pop_ref());
+            lua.register_userdata_metatable(mt_id as isize);
+
+            #[cfg(any(feature = "lua51", feature = "luajit"))]
+            let newtable = lua.create_table()?;
+            let destructor: DestructorCallback = Box::new(move |ud| {
+                let state = ud.lua.state;
+                let _sg = StackGuard::new(state);
+                assert_stack(state, 2);
+
+                ud.lua.push_ref(&ud);
+
+                // We know the destructor has not run yet because we hold a reference to the userdata.
+
+                // Deregister metatable
+                ffi::lua_getmetatable(state, -1);
+                let mt_id = ffi::lua_topointer(state, -1);
+                ffi::lua_pop(state, 1);
+                ud.lua.deregister_userdata_metatable(mt_id as isize);
+
+                // Clear uservalue
+                #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+                ffi::lua_pushnil(state);
+                #[cfg(any(feature = "lua51", feature = "luajit"))]
+                ud.lua.push_ref(&newtable.0);
+                ffi::lua_setuservalue(state, -2);
+
+                // A hack to drop non-static `T`
+                unsafe fn seal<T>(t: T) -> Box<dyn FnOnce() + 'static> {
+                    let f: Box<dyn FnOnce()> = Box::new(move || drop(t));
+                    mem::transmute(f)
                 }
 
-                init_userdata_metatable::<()>(lua.state, -2, Some(-1))?;
-                ffi::lua_pop(lua.state, 1);
-            }
+                vec![Box::new(seal(take_userdata::<UserDataCell<T>>(state)))]
+            });
+            self.destructors
+                .borrow_mut()
+                .push((ud.0.clone(), destructor));
 
-            ffi::lua_setmetatable(lua.state, -2);
-
-            Ok(AnyUserData(lua.pop_ref()))
+            Ok(ud)
         }
     }
 
     // Unsafe, because the callback can improperly capture any value with 'callback scope, such as
     // improperly capturing an argument. Since the 'callback lifetime is chosen by the user and the
     // lifetime of the callback itself is 'scope (non-'static), the borrow checker will happily pick
-    // a 'callback that outlives 'scope to allow this.  In order for this to be safe, the callback
+    // a 'callback that outlives 'scope to allow this. In order for this to be safe, the callback
     // must NOT capture any parameters.
     unsafe fn create_callback<'callback>(
         &self,
@@ -306,22 +449,100 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
         let f = mem::transmute::<Callback<'callback, 'scope>, Callback<'lua, 'static>>(f);
         let f = self.lua.create_callback(f)?;
 
-        let mut destructors = self.destructors.borrow_mut();
-        destructors.push((f.0.clone(), |f| {
+        let destructor: DestructorCallback = Box::new(|f| {
             let state = f.lua.state;
+            let _sg = StackGuard::new(state);
             assert_stack(state, 3);
+
             f.lua.push_ref(&f);
 
-            ffi::lua_getupvalue(state, -1, 1);
             // We know the destructor has not run yet because we hold a reference to the callback.
-            let ud = take_userdata::<Callback>(state);
 
+            ffi::lua_getupvalue(state, -1, 2);
+            let ud1 = take_userdata::<Callback>(state);
             ffi::lua_pushnil(state);
-            ffi::lua_setupvalue(state, -2, 1);
+            ffi::lua_setupvalue(state, -2, 2);
+
+            ffi::lua_getupvalue(state, -1, 3);
+            let ud2 = take_userdata::<Lua>(state);
+            ffi::lua_pushnil(state);
+            ffi::lua_setupvalue(state, -2, 3);
+
+            vec![Box::new(ud1), Box::new(ud2)]
+        });
+        self.destructors
+            .borrow_mut()
+            .push((f.0.clone(), destructor));
+
+        Ok(f)
+    }
+
+    #[cfg(feature = "async")]
+    unsafe fn create_async_callback<'callback>(
+        &self,
+        f: AsyncCallback<'callback, 'scope>,
+    ) -> Result<Function<'lua>> {
+        let f = mem::transmute::<AsyncCallback<'callback, 'scope>, AsyncCallback<'lua, 'static>>(f);
+        let f = self.lua.create_async_callback(f)?;
+
+        // We need to pre-allocate strings to avoid failures in destructor.
+        let get_poll_str = self.lua.create_string("get_poll")?;
+        let poll_str = self.lua.create_string("poll")?;
+        let destructor: DestructorCallback = Box::new(move |f| {
+            let state = f.lua.state;
+            let _sg = StackGuard::new(state);
+            assert_stack(state, 5);
+
+            f.lua.push_ref(&f);
+
+            // We know the destructor has not run yet because we hold a reference to the callback.
+
+            // First, get the environment table
+            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+            ffi::lua_getupvalue(state, -1, 1);
+            #[cfg(any(feature = "lua51", feature = "luajit"))]
+            ffi::lua_getfenv(state, -1);
+
+            // Second, get the `get_poll()` closure using the corresponding key
+            f.lua.push_ref(&get_poll_str.0);
+            ffi::lua_rawget(state, -2);
+
+            // Destroy all upvalues
+            ffi::lua_getupvalue(state, -1, 2);
+            let ud1 = take_userdata::<AsyncCallback>(state);
+            ffi::lua_pushnil(state);
+            ffi::lua_setupvalue(state, -2, 2);
+
+            ffi::lua_getupvalue(state, -1, 3);
+            let ud2 = take_userdata::<Lua>(state);
+            ffi::lua_pushnil(state);
+            ffi::lua_setupvalue(state, -2, 3);
 
             ffi::lua_pop(state, 1);
-            Box::new(ud)
-        }));
+            let mut data: Vec<Box<dyn Any>> = vec![Box::new(ud1), Box::new(ud2)];
+
+            // Finally, get polled future and destroy it
+            f.lua.push_ref(&poll_str.0);
+            if ffi::lua_rawget(state, -2) == ffi::LUA_TFUNCTION {
+                ffi::lua_getupvalue(state, -1, 2);
+                let ud3 = take_userdata::<LocalBoxFuture<Result<MultiValue>>>(state);
+                ffi::lua_pushnil(state);
+                ffi::lua_setupvalue(state, -2, 2);
+                data.push(Box::new(ud3));
+
+                ffi::lua_getupvalue(state, -1, 3);
+                let ud4 = take_userdata::<Lua>(state);
+                ffi::lua_pushnil(state);
+                ffi::lua_setupvalue(state, -2, 3);
+                data.push(Box::new(ud4));
+            }
+
+            data
+        });
+        self.destructors
+            .borrow_mut()
+            .push((f.0.clone(), destructor));
+
         Ok(f)
     }
 }
@@ -329,7 +550,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
 impl<'lua, 'scope> Drop for Scope<'lua, 'scope> {
     fn drop(&mut self) {
         // We separate the action of invalidating the userdata in Lua and actually dropping the
-        // userdata type into two phases.  This is so that, in the event a userdata drop panics, we
+        // userdata type into two phases. This is so that, in the event a userdata drop panics, we
         // can be sure that all of the userdata in Lua is actually invalidated.
 
         // All destructors are non-panicking, so this is fine
@@ -337,7 +558,7 @@ impl<'lua, 'scope> Drop for Scope<'lua, 'scope> {
             .destructors
             .get_mut()
             .drain(..)
-            .map(|(r, dest)| dest(r))
+            .flat_map(|(r, dest)| dest(r))
             .collect::<Vec<_>>();
 
         drop(to_drop);
@@ -368,10 +589,10 @@ impl<'lua, T: UserData> Default for NonStaticUserDataMethods<'lua, T> {
 impl<'lua, T: UserData> UserDataMethods<'lua, T> for NonStaticUserDataMethods<'lua, T> {
     fn add_method<S, A, R, M>(&mut self, name: &S, method: M)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + Fn(&'lua Lua, &T, A) -> Result<R>,
+        M: 'static + MaybeSend + Fn(&'lua Lua, &T, A) -> Result<R>,
     {
         self.methods.push((
             name.as_ref().to_vec(),
@@ -383,10 +604,10 @@ impl<'lua, T: UserData> UserDataMethods<'lua, T> for NonStaticUserDataMethods<'l
 
     fn add_method_mut<S, A, R, M>(&mut self, name: &S, mut method: M)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + FnMut(&'lua Lua, &mut T, A) -> Result<R>,
+        M: 'static + MaybeSend + FnMut(&'lua Lua, &mut T, A) -> Result<R>,
     {
         self.methods.push((
             name.as_ref().to_vec(),
@@ -396,12 +617,27 @@ impl<'lua, T: UserData> UserDataMethods<'lua, T> for NonStaticUserDataMethods<'l
         ));
     }
 
-    fn add_function<S, A, R, F>(&mut self, name: &S, function: F)
+    #[cfg(feature = "async")]
+    fn add_async_method<S, A, R, M, MR>(&mut self, _name: &S, _method: M)
     where
-        S: ?Sized + AsRef<[u8]>,
+        T: Clone,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>,
+        M: 'static + MaybeSend + Fn(&'lua Lua, T, A) -> MR,
+        MR: 'lua + Future<Output = Result<R>>,
+    {
+        // The panic should never happen as async non-static code wouldn't compile
+        // Non-static lifetime must be bounded to 'lua lifetime
+        mlua_panic!("asynchronous methods are not supported for non-static userdata")
+    }
+
+    fn add_function<S, A, R, F>(&mut self, name: &S, function: F)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLuaMulti<'lua>,
+        R: ToLuaMulti<'lua>,
+        F: 'static + MaybeSend + Fn(&'lua Lua, A) -> Result<R>,
     {
         self.methods.push((
             name.as_ref().to_vec(),
@@ -413,10 +649,10 @@ impl<'lua, T: UserData> UserDataMethods<'lua, T> for NonStaticUserDataMethods<'l
 
     fn add_function_mut<S, A, R, F>(&mut self, name: &S, mut function: F)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>,
+        F: 'static + MaybeSend + FnMut(&'lua Lua, A) -> Result<R>,
     {
         self.methods.push((
             name.as_ref().to_vec(),
@@ -426,59 +662,182 @@ impl<'lua, T: UserData> UserDataMethods<'lua, T> for NonStaticUserDataMethods<'l
         ));
     }
 
-    fn add_meta_method<A, R, M>(&mut self, meta: MetaMethod, method: M)
+    #[cfg(feature = "async")]
+    fn add_async_function<S, A, R, F, FR>(&mut self, _name: &S, _function: F)
     where
+        T: Clone,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + Fn(&'lua Lua, &T, A) -> Result<R>,
+        F: 'static + MaybeSend + Fn(&'lua Lua, A) -> FR,
+        FR: 'lua + Future<Output = Result<R>>,
+    {
+        // The panic should never happen as async non-static code wouldn't compile
+        // Non-static lifetime must be bounded to 'lua lifetime
+        mlua_panic!("asynchronous functions are not supported for non-static userdata")
+    }
+
+    fn add_meta_method<S, A, R, M>(&mut self, meta: S, method: M)
+    where
+        S: Into<MetaMethod>,
+        A: FromLuaMulti<'lua>,
+        R: ToLuaMulti<'lua>,
+        M: 'static + MaybeSend + Fn(&'lua Lua, &T, A) -> Result<R>,
     {
         self.meta_methods.push((
-            meta,
+            meta.into(),
             NonStaticMethod::Method(Box::new(move |lua, ud, args| {
                 method(lua, ud, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
             })),
         ));
     }
 
-    fn add_meta_method_mut<A, R, M>(&mut self, meta: MetaMethod, mut method: M)
+    fn add_meta_method_mut<S, A, R, M>(&mut self, meta: S, mut method: M)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + FnMut(&'lua Lua, &mut T, A) -> Result<R>,
+        M: 'static + MaybeSend + FnMut(&'lua Lua, &mut T, A) -> Result<R>,
     {
         self.meta_methods.push((
-            meta,
+            meta.into(),
             NonStaticMethod::MethodMut(Box::new(move |lua, ud, args| {
                 method(lua, ud, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
             })),
         ));
     }
 
-    fn add_meta_function<A, R, F>(&mut self, meta: MetaMethod, function: F)
+    fn add_meta_function<S, A, R, F>(&mut self, meta: S, function: F)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>,
+        F: 'static + MaybeSend + Fn(&'lua Lua, A) -> Result<R>,
     {
         self.meta_methods.push((
-            meta,
+            meta.into(),
             NonStaticMethod::Function(Box::new(move |lua, args| {
                 function(lua, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
             })),
         ));
     }
 
-    fn add_meta_function_mut<A, R, F>(&mut self, meta: MetaMethod, mut function: F)
+    fn add_meta_function_mut<S, A, R, F>(&mut self, meta: S, mut function: F)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>,
+        F: 'static + MaybeSend + FnMut(&'lua Lua, A) -> Result<R>,
     {
         self.meta_methods.push((
-            meta,
+            meta.into(),
             NonStaticMethod::FunctionMut(Box::new(move |lua, args| {
                 function(lua, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
             })),
         ));
     }
 }
+
+struct NonStaticUserDataFields<'lua, T: UserData> {
+    field_getters: Vec<(Vec<u8>, NonStaticMethod<'lua, T>)>,
+    field_setters: Vec<(Vec<u8>, NonStaticMethod<'lua, T>)>,
+    #[allow(clippy::type_complexity)]
+    meta_fields: Vec<(MetaMethod, Box<dyn Fn(&'lua Lua) -> Result<Value<'lua>>>)>,
+}
+
+impl<'lua, T: UserData> Default for NonStaticUserDataFields<'lua, T> {
+    fn default() -> NonStaticUserDataFields<'lua, T> {
+        NonStaticUserDataFields {
+            field_getters: Vec::new(),
+            field_setters: Vec::new(),
+            meta_fields: Vec::new(),
+        }
+    }
+}
+
+impl<'lua, T: UserData> UserDataFields<'lua, T> for NonStaticUserDataFields<'lua, T> {
+    fn add_field_method_get<S, R, M>(&mut self, name: &S, method: M)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        R: ToLua<'lua>,
+        M: 'static + MaybeSend + Fn(&'lua Lua, &T) -> Result<R>,
+    {
+        self.field_getters.push((
+            name.as_ref().to_vec(),
+            NonStaticMethod::Method(Box::new(move |lua, ud, _| {
+                method(lua, ud)?.to_lua_multi(lua)
+            })),
+        ));
+    }
+
+    fn add_field_method_set<S, A, M>(&mut self, name: &S, mut method: M)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLua<'lua>,
+        M: 'static + MaybeSend + FnMut(&'lua Lua, &mut T, A) -> Result<()>,
+    {
+        self.field_setters.push((
+            name.as_ref().to_vec(),
+            NonStaticMethod::MethodMut(Box::new(move |lua, ud, args| {
+                method(lua, ud, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
+            })),
+        ));
+    }
+
+    fn add_field_function_get<S, R, F>(&mut self, name: &S, function: F)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        R: ToLua<'lua>,
+        F: 'static + MaybeSend + Fn(&'lua Lua, AnyUserData<'lua>) -> Result<R>,
+    {
+        self.field_getters.push((
+            name.as_ref().to_vec(),
+            NonStaticMethod::Function(Box::new(move |lua, args| {
+                function(lua, AnyUserData::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
+            })),
+        ));
+    }
+
+    fn add_field_function_set<S, A, F>(&mut self, name: &S, mut function: F)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLua<'lua>,
+        F: 'static + MaybeSend + FnMut(&'lua Lua, AnyUserData<'lua>, A) -> Result<()>,
+    {
+        self.field_setters.push((
+            name.as_ref().to_vec(),
+            NonStaticMethod::FunctionMut(Box::new(move |lua, args| {
+                let (ud, val) = <_>::from_lua_multi(args, lua)?;
+                function(lua, ud, val)?.to_lua_multi(lua)
+            })),
+        ));
+    }
+
+    fn add_meta_field_with<S, R, F>(&mut self, meta: S, f: F)
+    where
+        S: Into<MetaMethod>,
+        F: 'static + MaybeSend + Fn(&'lua Lua) -> Result<R>,
+        R: ToLua<'lua>,
+    {
+        let meta = meta.into();
+        self.meta_fields.push((
+            meta.clone(),
+            Box::new(move |lua| {
+                let value = f(lua)?.to_lua(lua)?;
+                if meta == MetaMethod::Index || meta == MetaMethod::NewIndex {
+                    match value {
+                        Value::Nil | Value::Table(_) | Value::Function(_) => {}
+                        _ => {
+                            return Err(Error::MetaMethodTypeError {
+                                method: meta.to_string(),
+                                type_name: value.type_name(),
+                                message: Some("expected nil, table or function".to_string()),
+                            })
+                        }
+                    }
+                }
+                Ok(value)
+            }),
+        ));
+    }
+}

src/serde/de.rs

@@ -0,0 +1,337 @@
+use std::string::String as StdString;
+
+use serde::de::{self, IntoDeserializer};
+
+use crate::error::{Error, Result};
+use crate::table::{TablePairs, TableSequence};
+use crate::value::Value;
+
+/// A struct for deserializing Lua values into Rust values.
+#[derive(Debug)]
+pub struct Deserializer<'lua>(Value<'lua>);
+
+impl<'lua> Deserializer<'lua> {
+    /// Creates a new Lua Deserializer for the `Value`.
+    pub fn new(value: Value<'lua>) -> Self {
+        Deserializer(value)
+    }
+}
+
+impl<'lua, 'de> serde::Deserializer<'de> for Deserializer<'lua> {
+    type Error = Error;
+
+    #[inline]
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        match self.0 {
+            Value::Nil => visitor.visit_unit(),
+            Value::Boolean(b) => visitor.visit_bool(b),
+            #[allow(clippy::useless_conversion)]
+            Value::Integer(i) => visitor.visit_i64(i.into()),
+            #[allow(clippy::useless_conversion)]
+            Value::Number(n) => visitor.visit_f64(n.into()),
+            Value::String(s) => match s.to_str() {
+                Ok(s) => visitor.visit_str(s),
+                Err(_) => visitor.visit_bytes(s.as_bytes()),
+            },
+            Value::Table(ref t) if t.raw_len() > 0 || t.is_array() => self.deserialize_seq(visitor),
+            Value::Table(_) => self.deserialize_map(visitor),
+            Value::LightUserData(ud) if ud.0.is_null() => visitor.visit_none(),
+            Value::Function(_)
+            | Value::Thread(_)
+            | Value::UserData(_)
+            | Value::LightUserData(_)
+            | Value::Error(_) => Err(de::Error::custom("invalid value type")),
+        }
+    }
+
+    #[inline]
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        match self.0 {
+            Value::Nil => visitor.visit_none(),
+            Value::LightUserData(ud) if ud.0.is_null() => visitor.visit_none(),
+            _ => visitor.visit_some(self),
+        }
+    }
+
+    #[inline]
+    fn deserialize_enum<V>(
+        self,
+        _name: &str,
+        _variants: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        let (variant, value) = match self.0 {
+            Value::Table(value) => {
+                let mut iter = value.pairs::<StdString, Value>();
+                let (variant, value) = match iter.next() {
+                    Some(v) => v?,
+                    None => {
+                        return Err(de::Error::invalid_value(
+                            de::Unexpected::Map,
+                            &"map with a single key",
+                        ))
+                    }
+                };
+
+                if iter.next().is_some() {
+                    return Err(de::Error::invalid_value(
+                        de::Unexpected::Map,
+                        &"map with a single key",
+                    ));
+                }
+                (variant, Some(value))
+            }
+            Value::String(variant) => (variant.to_str()?.to_owned(), None),
+            _ => return Err(de::Error::custom("bad enum value")),
+        };
+
+        visitor.visit_enum(EnumDeserializer { variant, value })
+    }
+
+    #[inline]
+    fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        match self.0 {
+            Value::Table(t) => {
+                let len = t.raw_len() as usize;
+                let mut deserializer = SeqDeserializer(t.raw_sequence_values());
+                let seq = visitor.visit_seq(&mut deserializer)?;
+                if deserializer.0.count() == 0 {
+                    Ok(seq)
+                } else {
+                    Err(de::Error::invalid_length(
+                        len,
+                        &"fewer elements in the table",
+                    ))
+                }
+            }
+            _ => Err(de::Error::custom("invalid value type")),
+        }
+    }
+
+    #[inline]
+    fn deserialize_tuple<V>(self, _len: usize, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        self.deserialize_seq(visitor)
+    }
+
+    #[inline]
+    fn deserialize_tuple_struct<V>(
+        self,
+        _name: &'static str,
+        _len: usize,
+        visitor: V,
+    ) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        self.deserialize_seq(visitor)
+    }
+
+    #[inline]
+    fn deserialize_map<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        match self.0 {
+            Value::Table(t) => {
+                let mut deserializer = MapDeserializer::new(t.pairs());
+                let map = visitor.visit_map(&mut deserializer)?;
+                let count = deserializer.pairs.count();
+                if count == 0 {
+                    Ok(map)
+                } else {
+                    Err(de::Error::invalid_length(
+                        deserializer.processed + count,
+                        &"fewer elements in the table",
+                    ))
+                }
+            }
+            _ => Err(de::Error::custom("invalid value type")),
+        }
+    }
+
+    #[inline]
+    fn deserialize_struct<V>(
+        self,
+        _name: &'static str,
+        _fields: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        self.deserialize_map(visitor)
+    }
+
+    serde::forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
+        byte_buf unit unit_struct newtype_struct
+        identifier ignored_any
+    }
+}
+
+struct SeqDeserializer<'lua>(TableSequence<'lua, Value<'lua>>);
+
+impl<'lua, 'de> de::SeqAccess<'de> for SeqDeserializer<'lua> {
+    type Error = Error;
+
+    fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>>
+    where
+        T: de::DeserializeSeed<'de>,
+    {
+        match self.0.next() {
+            Some(value) => seed.deserialize(Deserializer(value?)).map(Some),
+            None => Ok(None),
+        }
+    }
+
+    fn size_hint(&self) -> Option<usize> {
+        match self.0.size_hint() {
+            (lower, Some(upper)) if lower == upper => Some(upper),
+            _ => None,
+        }
+    }
+}
+
+struct MapDeserializer<'lua> {
+    pairs: TablePairs<'lua, Value<'lua>, Value<'lua>>,
+    value: Option<Value<'lua>>,
+    processed: usize,
+}
+
+impl<'lua> MapDeserializer<'lua> {
+    fn new(pairs: TablePairs<'lua, Value<'lua>, Value<'lua>>) -> Self {
+        MapDeserializer {
+            pairs,
+            value: None,
+            processed: 0,
+        }
+    }
+}
+
+impl<'lua, 'de> de::MapAccess<'de> for MapDeserializer<'lua> {
+    type Error = Error;
+
+    fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>>
+    where
+        T: de::DeserializeSeed<'de>,
+    {
+        match self.pairs.next() {
+            Some(item) => {
+                let (key, value) = item?;
+                self.processed += 1;
+                self.value = Some(value);
+                let key_de = Deserializer(key);
+                seed.deserialize(key_de).map(Some)
+            }
+            None => Ok(None),
+        }
+    }
+
+    fn next_value_seed<T>(&mut self, seed: T) -> Result<T::Value>
+    where
+        T: de::DeserializeSeed<'de>,
+    {
+        match self.value.take() {
+            Some(value) => seed.deserialize(Deserializer(value)),
+            None => Err(de::Error::custom("value is missing")),
+        }
+    }
+
+    fn size_hint(&self) -> Option<usize> {
+        match self.pairs.size_hint() {
+            (lower, Some(upper)) if lower == upper => Some(upper),
+            _ => None,
+        }
+    }
+}
+
+struct EnumDeserializer<'lua> {
+    variant: StdString,
+    value: Option<Value<'lua>>,
+}
+
+impl<'lua, 'de> de::EnumAccess<'de> for EnumDeserializer<'lua> {
+    type Error = Error;
+    type Variant = VariantDeserializer<'lua>;
+
+    fn variant_seed<T>(self, seed: T) -> Result<(T::Value, Self::Variant)>
+    where
+        T: de::DeserializeSeed<'de>,
+    {
+        let variant = self.variant.into_deserializer();
+        let variant_access = VariantDeserializer { value: self.value };
+        seed.deserialize(variant).map(|v| (v, variant_access))
+    }
+}
+
+struct VariantDeserializer<'lua> {
+    value: Option<Value<'lua>>,
+}
+
+impl<'lua, 'de> de::VariantAccess<'de> for VariantDeserializer<'lua> {
+    type Error = Error;
+
+    fn unit_variant(self) -> Result<()> {
+        match self.value {
+            Some(_) => Err(de::Error::invalid_type(
+                de::Unexpected::NewtypeVariant,
+                &"unit variant",
+            )),
+            None => Ok(()),
+        }
+    }
+
+    fn newtype_variant_seed<T>(self, seed: T) -> Result<T::Value>
+    where
+        T: de::DeserializeSeed<'de>,
+    {
+        match self.value {
+            Some(value) => seed.deserialize(Deserializer(value)),
+            None => Err(de::Error::invalid_type(
+                de::Unexpected::UnitVariant,
+                &"newtype variant",
+            )),
+        }
+    }
+
+    fn tuple_variant<V>(self, _len: usize, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        match self.value {
+            Some(value) => serde::Deserializer::deserialize_seq(Deserializer(value), visitor),
+            None => Err(de::Error::invalid_type(
+                de::Unexpected::UnitVariant,
+                &"tuple variant",
+            )),
+        }
+    }
+
+    fn struct_variant<V>(self, _fields: &'static [&'static str], visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        match self.value {
+            Some(value) => serde::Deserializer::deserialize_map(Deserializer(value), visitor),
+            None => Err(de::Error::invalid_type(
+                de::Unexpected::UnitVariant,
+                &"struct variant",
+            )),
+        }
+    }
+}

src/serde/mod.rs

@@ -0,0 +1,227 @@
+//! (De)Serialization support using serde.
+
+use std::os::raw::c_void;
+use std::ptr;
+
+use serde::{Deserialize, Serialize};
+
+use crate::error::Result;
+use crate::ffi;
+use crate::lua::Lua;
+use crate::table::Table;
+use crate::types::LightUserData;
+use crate::util::{assert_stack, check_stack, StackGuard};
+use crate::value::Value;
+
+/// Trait for serializing/deserializing Lua values using Serde.
+pub trait LuaSerdeExt<'lua> {
+    /// A special value (lightuserdata) to encode/decode optional (none) values.
+    ///
+    /// Requires `feature = "serialize"`
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::collections::HashMap;
+    /// use mlua::{Lua, Result, LuaSerdeExt};
+    ///
+    /// fn main() -> Result<()> {
+    ///     let lua = Lua::new();
+    ///     lua.globals().set("null", lua.null())?;
+    ///
+    ///     let val = lua.load(r#"{a = null}"#).eval()?;
+    ///     let map: HashMap<String, Option<String>> = lua.from_value(val)?;
+    ///     assert_eq!(map["a"], None);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    fn null(&'lua self) -> Value<'lua>;
+
+    /// A metatable attachable to a Lua table to systematically encode it as Array (instead of Map).
+    /// As result, encoded Array will contain only sequence part of the table, with the same length
+    /// as the `#` operator on that table.
+    ///
+    /// Requires `feature = "serialize"`
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use mlua::{Lua, Result, LuaSerdeExt};
+    /// use serde_json::Value as JsonValue;
+    ///
+    /// fn main() -> Result<()> {
+    ///     let lua = Lua::new();
+    ///     lua.globals().set("array_mt", lua.array_metatable())?;
+    ///
+    ///     // Encode as an empty array (no sequence part in the lua table)
+    ///     let val = lua.load("setmetatable({a = 5}, array_mt)").eval()?;
+    ///     let j: JsonValue = lua.from_value(val)?;
+    ///     assert_eq!(j.to_string(), "[]");
+    ///
+    ///     // Encode as object
+    ///     let val = lua.load("{a = 5}").eval()?;
+    ///     let j: JsonValue = lua.from_value(val)?;
+    ///     assert_eq!(j.to_string(), r#"{"a":5}"#);
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    fn array_metatable(&'lua self) -> Table<'lua>;
+
+    /// Converts `T` into a `Value` instance.
+    ///
+    /// Requires `feature = "serialize"`
+    ///
+    /// [`Value`]: enum.Value.html
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use mlua::{Lua, Result, LuaSerdeExt};
+    /// use serde::Serialize;
+    ///
+    /// #[derive(Serialize)]
+    /// struct User {
+    ///     name: String,
+    ///     age: u8,
+    /// }
+    ///
+    /// fn main() -> Result<()> {
+    ///     let lua = Lua::new();
+    ///     let u = User {
+    ///         name: "John Smith".into(),
+    ///         age: 20,
+    ///     };
+    ///     lua.globals().set("user", lua.to_value(&u)?)?;
+    ///     lua.load(r#"
+    ///         assert(user["name"] == "John Smith")
+    ///         assert(user["age"] == 20)
+    ///     "#).exec()
+    /// }
+    /// ```
+    fn to_value<T: Serialize + ?Sized>(&'lua self, t: &T) -> Result<Value<'lua>>;
+
+    /// Converts `T` into a `Value` instance with options.
+    ///
+    /// Requires `feature = "serialize"`
+    ///
+    /// [`Value`]: enum.Value.html
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use mlua::{Lua, Result, LuaSerdeExt, SerializeOptions};
+    ///
+    /// fn main() -> Result<()> {
+    ///     let lua = Lua::new();
+    ///     let v = vec![1, 2, 3];
+    ///     let options = SerializeOptions::new().set_array_metatable(false);
+    ///     lua.globals().set("v", lua.to_value_with(&v, options)?)?;
+    ///
+    ///     lua.load(r#"
+    ///         assert(#v == 3 and v[1] == 1 and v[2] == 2 and v[3] == 3)
+    ///         assert(getmetatable(v) == nil)
+    ///     "#).exec()
+    /// }
+    /// ```
+    fn to_value_with<T>(&'lua self, t: &T, options: ser::Options) -> Result<Value<'lua>>
+    where
+        T: Serialize + ?Sized;
+
+    /// Deserializes a `Value` into any serde deserializable object.
+    ///
+    /// Requires `feature = "serialize"`
+    ///
+    /// [`Value`]: enum.Value.html
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use mlua::{Lua, Result, LuaSerdeExt};
+    /// use serde::Deserialize;
+    ///
+    /// #[derive(Deserialize, Debug, PartialEq)]
+    /// struct User {
+    ///     name: String,
+    ///     age: u8,
+    /// }
+    ///
+    /// fn main() -> Result<()> {
+    ///     let lua = Lua::new();
+    ///     let val = lua.load(r#"{name = "John Smith", age = 20}"#).eval()?;
+    ///     let u: User = lua.from_value(val)?;
+    ///
+    ///     assert_eq!(u, User { name: "John Smith".into(), age: 20 });
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    fn from_value<T: Deserialize<'lua>>(&'lua self, value: Value<'lua>) -> Result<T>;
+}
+
+impl<'lua> LuaSerdeExt<'lua> for Lua {
+    fn null(&'lua self) -> Value<'lua> {
+        Value::LightUserData(LightUserData(ptr::null_mut()))
+    }
+
+    fn array_metatable(&'lua self) -> Table<'lua> {
+        unsafe {
+            let _sg = StackGuard::new(self.state);
+            assert_stack(self.state, 1);
+
+            push_array_metatable(self.state);
+
+            Table(self.pop_ref())
+        }
+    }
+
+    fn to_value<T>(&'lua self, t: &T) -> Result<Value<'lua>>
+    where
+        T: Serialize + ?Sized,
+    {
+        t.serialize(ser::Serializer::new(self))
+    }
+
+    fn to_value_with<T>(&'lua self, t: &T, options: ser::Options) -> Result<Value<'lua>>
+    where
+        T: Serialize + ?Sized,
+    {
+        t.serialize(ser::Serializer::new_with_options(self, options))
+    }
+
+    fn from_value<T>(&'lua self, value: Value<'lua>) -> Result<T>
+    where
+        T: Deserialize<'lua>,
+    {
+        T::deserialize(de::Deserializer::new(value))
+    }
+}
+
+// Uses 6 stack spaces and calls checkstack.
+pub(crate) unsafe fn init_metatables(state: *mut ffi::lua_State) -> Result<()> {
+    check_stack(state, 6)?;
+
+    ffi::safe::lua_createtable(state, 0, 1)?;
+
+    ffi::lua_pushboolean(state, 0);
+    ffi::safe::lua_rawsetfield(state, -2, "__metatable")?;
+
+    let array_metatable_key = &ARRAY_METATABLE_REGISTRY_KEY as *const u8 as *const c_void;
+    ffi::safe::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, array_metatable_key)
+}
+
+pub(crate) unsafe fn push_array_metatable(state: *mut ffi::lua_State) {
+    let array_metatable_key = &ARRAY_METATABLE_REGISTRY_KEY as *const u8 as *mut c_void;
+    ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, array_metatable_key);
+}
+
+static ARRAY_METATABLE_REGISTRY_KEY: u8 = 0;
+
+pub mod de;
+pub mod ser;
+
+#[doc(inline)]
+pub use de::Deserializer;
+#[doc(inline)]
+pub use ser::Serializer;

src/serde/ser.rs

@@ -0,0 +1,478 @@
+use std::os::raw::c_int;
+
+use serde::{ser, Serialize};
+
+use super::LuaSerdeExt;
+use crate::error::{Error, Result};
+use crate::ffi;
+use crate::lua::Lua;
+use crate::string::String;
+use crate::table::Table;
+use crate::types::Integer;
+use crate::util::{check_stack, StackGuard};
+use crate::value::{ToLua, Value};
+
+/// A struct for serializing Rust values into Lua values.
+#[derive(Debug)]
+pub struct Serializer<'lua> {
+    lua: &'lua Lua,
+    options: Options,
+}
+
+/// A struct with options to change default serializer behaviour.
+#[derive(Debug, Clone, Copy)]
+#[non_exhaustive]
+pub struct Options {
+    /// If true, sequence serialization to a Lua table will create table
+    /// with the [`array_metatable`] attached.
+    ///
+    /// Default: **true**
+    ///
+    /// [`array_metatable`]: ../trait.LuaSerdeExt.html#tymethod.array_metatable
+    pub set_array_metatable: bool,
+
+    /// If true, serialize `None` (part of `Option` type) to [`null`].
+    /// Otherwise it will be set to Lua [`Nil`].
+    ///
+    /// Default: **true**
+    ///
+    /// [`null`]: ../trait.LuaSerdeExt.html#tymethod.null
+    /// [`Nil`]: ../../enum.Value.html#variant.Nil
+    pub serialize_none_to_null: bool,
+
+    /// If true, serialize `Unit` (type of `()` in Rust) and Unit structs to [`null`].
+    /// Otherwise it will be set to Lua [`Nil`].
+    ///
+    /// Default: **true**
+    ///
+    /// [`null`]: ../trait.LuaSerdeExt.html#tymethod.null
+    /// [`Nil`]: ../../enum.Value.html#variant.Nil
+    pub serialize_unit_to_null: bool,
+}
+
+impl Default for Options {
+    fn default() -> Self {
+        Options {
+            set_array_metatable: true,
+            serialize_none_to_null: true,
+            serialize_unit_to_null: true,
+        }
+    }
+}
+
+impl Options {
+    /// Retruns a new instance of `Options` with default parameters.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Sets [`set_array_metatable`] option.
+    ///
+    /// [`set_array_metatable`]: #structfield.set_array_metatable
+    pub fn set_array_metatable(mut self, enabled: bool) -> Self {
+        self.set_array_metatable = enabled;
+        self
+    }
+
+    /// Sets [`serialize_none_to_null`] option.
+    ///
+    /// [`serialize_none_to_null`]: #structfield.serialize_none_to_null
+    pub fn serialize_none_to_null(mut self, enabled: bool) -> Self {
+        self.serialize_none_to_null = enabled;
+        self
+    }
+
+    /// Sets [`serialize_unit_to_null`] option.
+    ///
+    /// [`serialize_unit_to_null`]: #structfield.serialize_unit_to_null
+    pub fn serialize_unit_to_null(mut self, enabled: bool) -> Self {
+        self.serialize_unit_to_null = enabled;
+        self
+    }
+}
+
+impl<'lua> Serializer<'lua> {
+    /// Creates a new Lua Serializer with default options.
+    pub fn new(lua: &'lua Lua) -> Self {
+        Self::new_with_options(lua, Options::default())
+    }
+
+    /// Creates a new Lua Serializer with custom options.
+    pub fn new_with_options(lua: &'lua Lua, options: Options) -> Self {
+        Serializer { lua, options }
+    }
+}
+
+macro_rules! lua_serialize_number {
+    ($name:ident, $t:ty) => {
+        #[inline]
+        fn $name(self, value: $t) -> Result<Value<'lua>> {
+            value.to_lua(self.lua)
+        }
+    };
+}
+
+impl<'lua> ser::Serializer for Serializer<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    // Associated types for keeping track of additional state while serializing
+    // compound data structures like sequences and maps.
+    type SerializeSeq = SerializeVec<'lua>;
+    type SerializeTuple = SerializeVec<'lua>;
+    type SerializeTupleStruct = SerializeVec<'lua>;
+    type SerializeTupleVariant = SerializeTupleVariant<'lua>;
+    type SerializeMap = SerializeMap<'lua>;
+    type SerializeStruct = SerializeMap<'lua>;
+    type SerializeStructVariant = SerializeStructVariant<'lua>;
+
+    #[inline]
+    fn serialize_bool(self, value: bool) -> Result<Value<'lua>> {
+        Ok(Value::Boolean(value))
+    }
+
+    lua_serialize_number!(serialize_i8, i8);
+    lua_serialize_number!(serialize_u8, u8);
+    lua_serialize_number!(serialize_i16, i16);
+    lua_serialize_number!(serialize_u16, u16);
+    lua_serialize_number!(serialize_i32, i32);
+    lua_serialize_number!(serialize_u32, u32);
+    lua_serialize_number!(serialize_i64, i64);
+    lua_serialize_number!(serialize_u64, u64);
+
+    lua_serialize_number!(serialize_f32, f32);
+    lua_serialize_number!(serialize_f64, f64);
+
+    #[inline]
+    fn serialize_char(self, value: char) -> Result<Value<'lua>> {
+        self.serialize_str(&value.to_string())
+    }
+
+    #[inline]
+    fn serialize_str(self, value: &str) -> Result<Value<'lua>> {
+        self.lua.create_string(value).map(Value::String)
+    }
+
+    #[inline]
+    fn serialize_bytes(self, value: &[u8]) -> Result<Value<'lua>> {
+        self.lua.create_string(value).map(Value::String)
+    }
+
+    #[inline]
+    fn serialize_none(self) -> Result<Value<'lua>> {
+        if self.options.serialize_none_to_null {
+            Ok(self.lua.null())
+        } else {
+            Ok(Value::Nil)
+        }
+    }
+
+    #[inline]
+    fn serialize_some<T>(self, value: &T) -> Result<Value<'lua>>
+    where
+        T: Serialize + ?Sized,
+    {
+        value.serialize(self)
+    }
+
+    #[inline]
+    fn serialize_unit(self) -> Result<Value<'lua>> {
+        if self.options.serialize_unit_to_null {
+            Ok(self.lua.null())
+        } else {
+            Ok(Value::Nil)
+        }
+    }
+
+    #[inline]
+    fn serialize_unit_struct(self, _name: &'static str) -> Result<Value<'lua>> {
+        if self.options.serialize_unit_to_null {
+            Ok(self.lua.null())
+        } else {
+            Ok(Value::Nil)
+        }
+    }
+
+    #[inline]
+    fn serialize_unit_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+    ) -> Result<Value<'lua>> {
+        self.serialize_str(variant)
+    }
+
+    #[inline]
+    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<Value<'lua>>
+    where
+        T: Serialize + ?Sized,
+    {
+        value.serialize(self)
+    }
+
+    #[inline]
+    fn serialize_newtype_variant<T>(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+        value: &T,
+    ) -> Result<Value<'lua>>
+    where
+        T: Serialize + ?Sized,
+    {
+        let table = self.lua.create_table()?;
+        let variant = self.lua.create_string(variant)?;
+        let value = self.lua.to_value_with(value, self.options)?;
+        table.raw_set(variant, value)?;
+        Ok(Value::Table(table))
+    }
+
+    #[inline]
+    fn serialize_seq(self, len: Option<usize>) -> Result<Self::SerializeSeq> {
+        let len = len.unwrap_or(0) as c_int;
+        let table = self.lua.create_table_with_capacity(len, 0)?;
+        if self.options.set_array_metatable {
+            table.set_metatable(Some(self.lua.array_metatable()));
+        }
+        let options = self.options;
+        Ok(SerializeVec { table, options })
+    }
+
+    #[inline]
+    fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple> {
+        self.serialize_seq(Some(len))
+    }
+
+    #[inline]
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        len: usize,
+    ) -> Result<Self::SerializeTupleStruct> {
+        self.serialize_seq(Some(len))
+    }
+
+    #[inline]
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleVariant> {
+        Ok(SerializeTupleVariant {
+            name: self.lua.create_string(variant)?,
+            table: self.lua.create_table()?,
+            options: self.options,
+        })
+    }
+
+    #[inline]
+    fn serialize_map(self, len: Option<usize>) -> Result<Self::SerializeMap> {
+        let len = len.unwrap_or(0) as c_int;
+        Ok(SerializeMap {
+            key: None,
+            table: self.lua.create_table_with_capacity(0, len)?,
+            options: self.options,
+        })
+    }
+
+    #[inline]
+    fn serialize_struct(self, _name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
+        self.serialize_map(Some(len))
+    }
+
+    #[inline]
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+        len: usize,
+    ) -> Result<Self::SerializeStructVariant> {
+        Ok(SerializeStructVariant {
+            name: self.lua.create_string(variant)?,
+            table: self.lua.create_table_with_capacity(0, len as c_int)?,
+            options: self.options,
+        })
+    }
+}
+
+#[doc(hidden)]
+pub struct SerializeVec<'lua> {
+    table: Table<'lua>,
+    options: Options,
+}
+
+impl<'lua> ser::SerializeSeq for SerializeVec<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        let lua = self.table.0.lua;
+        let value = lua.to_value_with(value, self.options)?;
+        unsafe {
+            let _sg = StackGuard::new(lua.state);
+            check_stack(lua.state, 6)?;
+
+            lua.push_ref(&self.table.0);
+            lua.push_value(value)?;
+            let len = ffi::lua_rawlen(lua.state, -2) as Integer;
+            ffi::safe::lua_rawseti(lua.state, -2, len + 1)
+        }
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        Ok(Value::Table(self.table))
+    }
+}
+
+impl<'lua> ser::SerializeTuple for SerializeVec<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        ser::SerializeSeq::serialize_element(self, value)
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        ser::SerializeSeq::end(self)
+    }
+}
+
+impl<'lua> ser::SerializeTupleStruct for SerializeVec<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        ser::SerializeSeq::serialize_element(self, value)
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        ser::SerializeSeq::end(self)
+    }
+}
+
+#[doc(hidden)]
+pub struct SerializeTupleVariant<'lua> {
+    name: String<'lua>,
+    table: Table<'lua>,
+    options: Options,
+}
+
+impl<'lua> ser::SerializeTupleVariant for SerializeTupleVariant<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        let lua = self.table.0.lua;
+        let idx = self.table.raw_len() + 1;
+        self.table
+            .raw_insert(idx, lua.to_value_with(value, self.options)?)
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        let lua = self.table.0.lua;
+        let table = lua.create_table()?;
+        table.raw_set(self.name, self.table)?;
+        Ok(Value::Table(table))
+    }
+}
+
+#[doc(hidden)]
+pub struct SerializeMap<'lua> {
+    table: Table<'lua>,
+    key: Option<Value<'lua>>,
+    options: Options,
+}
+
+impl<'lua> ser::SerializeMap for SerializeMap<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        let lua = self.table.0.lua;
+        self.key = Some(lua.to_value_with(key, self.options)?);
+        Ok(())
+    }
+
+    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        let lua = self.table.0.lua;
+        let key = mlua_expect!(
+            self.key.take(),
+            "serialize_value called before serialize_key"
+        );
+        let value = lua.to_value_with(value, self.options)?;
+        self.table.raw_set(key, value)
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        Ok(Value::Table(self.table))
+    }
+}
+
+impl<'lua> ser::SerializeStruct for SerializeMap<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        ser::SerializeMap::serialize_key(self, key)?;
+        ser::SerializeMap::serialize_value(self, value)
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        ser::SerializeMap::end(self)
+    }
+}
+
+#[doc(hidden)]
+pub struct SerializeStructVariant<'lua> {
+    name: String<'lua>,
+    table: Table<'lua>,
+    options: Options,
+}
+
+impl<'lua> ser::SerializeStructVariant for SerializeStructVariant<'lua> {
+    type Ok = Value<'lua>;
+    type Error = Error;
+
+    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
+    where
+        T: Serialize + ?Sized,
+    {
+        let lua = self.table.0.lua;
+        self.table
+            .raw_set(key, lua.to_value_with(value, self.options)?)?;
+        Ok(())
+    }
+
+    fn end(self) -> Result<Value<'lua>> {
+        let lua = self.table.0.lua;
+        let table = lua.create_table()?;
+        table.raw_set(self.name, self.table)?;
+        Ok(Value::Table(table))
+    }
+}

src/stdlib.rs

@@ -1,31 +1,58 @@
 use std::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign};
 use std::u32;
 
-/// Flags describing the set of lua modules to load.
+/// Flags describing the set of lua standard libraries to load.
 #[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
 pub struct StdLib(u32);
 
 impl StdLib {
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
-    pub const COROUTINE: StdLib = StdLib(1 << 0);
+    /// [`coroutine`](https://www.lua.org/manual/5.3/manual.html#6.2) library
+    ///
+    /// Requires `feature = "lua54/lua53/lua52"`
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", doc))]
+    pub const COROUTINE: StdLib = StdLib(1);
+    /// [`table`](https://www.lua.org/manual/5.3/manual.html#6.6) library
     pub const TABLE: StdLib = StdLib(1 << 1);
+    /// [`io`](https://www.lua.org/manual/5.3/manual.html#6.8) library
     pub const IO: StdLib = StdLib(1 << 2);
+    /// [`os`](https://www.lua.org/manual/5.3/manual.html#6.9) library
     pub const OS: StdLib = StdLib(1 << 3);
+    /// [`string`](https://www.lua.org/manual/5.3/manual.html#6.4) library
     pub const STRING: StdLib = StdLib(1 << 4);
-    #[cfg(feature = "lua53")]
+    /// [`utf8`](https://www.lua.org/manual/5.3/manual.html#6.5) library
+    ///
+    /// Requires `feature = "lua54/lua53"`
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     pub const UTF8: StdLib = StdLib(1 << 5);
-    #[cfg(any(feature = "lua52", feature = "luajit"))]
+    /// [`bit`](https://www.lua.org/manual/5.2/manual.html#6.7) library
+    ///
+    /// Requires `feature = "lua52/luajit"`
+    #[cfg(any(feature = "lua52", feature = "luajit", doc))]
     pub const BIT: StdLib = StdLib(1 << 6);
+    /// [`math`](https://www.lua.org/manual/5.3/manual.html#6.7) library
     pub const MATH: StdLib = StdLib(1 << 7);
+    /// [`package`](https://www.lua.org/manual/5.3/manual.html#6.3) library
     pub const PACKAGE: StdLib = StdLib(1 << 8);
-    #[cfg(feature = "luajit")]
+    /// [`jit`](http://luajit.org/ext_jit.html) library
+    ///
+    /// Requires `feature = "luajit"`
+    #[cfg(any(feature = "luajit", doc))]
     pub const JIT: StdLib = StdLib(1 << 9);
-    #[cfg(feature = "luajit")]
-    pub const FFI: StdLib = StdLib(1 << 10);
-    pub const DEBUG: StdLib = StdLib(1 << 31); // always highest bit
 
+    /// (**unsafe**) [`ffi`](http://luajit.org/ext_ffi.html) library
+    ///
+    /// Requires `feature = "luajit"`
+    #[cfg(any(feature = "luajit", doc))]
+    pub const FFI: StdLib = StdLib(1 << 30);
+    /// (**unsafe**) [`debug`](https://www.lua.org/manual/5.3/manual.html#6.10) library
+    pub const DEBUG: StdLib = StdLib(1 << 31);
+
+    /// No libraries
+    pub const NONE: StdLib = StdLib(0);
+    /// (**unsafe**) All standard libraries
     pub const ALL: StdLib = StdLib(u32::MAX);
-    pub const ALL_NO_DEBUG: StdLib = StdLib((1 << 31) - 1);
+    /// The safe subset of the standard libraries
+    pub const ALL_SAFE: StdLib = StdLib((1 << 30) - 1);
 
     pub fn contains(self, lib: Self) -> bool {
         (self & lib).0 != 0

src/string.rs

@@ -1,5 +1,11 @@
 use std::{slice, str};
 
+#[cfg(feature = "serialize")]
+use {
+    serde::ser::{Serialize, Serializer},
+    std::result::Result as StdResult,
+};
+
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::types::LuaRef;
@@ -105,3 +111,16 @@ where
         self.as_bytes() == other.as_ref()
     }
 }
+
+#[cfg(feature = "serialize")]
+impl<'lua> Serialize for String<'lua> {
+    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        match self.to_str() {
+            Ok(s) => serializer.serialize_str(s),
+            Err(_) => serializer.serialize_bytes(self.as_bytes()),
+        }
+    }
+}

src/table.rs

@@ -1,17 +1,26 @@
 use std::marker::PhantomData;
-use std::os::raw::c_int;
+
+#[cfg(feature = "serialize")]
+use {
+    serde::ser::{Serialize, SerializeMap, SerializeSeq, Serializer},
+    std::result::Result as StdResult,
+};
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::function::Function;
 use crate::types::{Integer, LuaRef};
-use crate::util::{assert_stack, protect_lua, protect_lua_closure, StackGuard};
+use crate::util::{assert_stack, check_stack, StackGuard};
 use crate::value::{FromLua, FromLuaMulti, Nil, ToLua, ToLuaMulti, Value};
 
+#[cfg(feature = "async")]
+use {futures_core::future::LocalBoxFuture, futures_util::future};
+
 /// Handle to an internal Lua table.
 #[derive(Clone, Debug)]
 pub struct Table<'lua>(pub(crate) LuaRef<'lua>);
 
+#[allow(clippy::len_without_is_empty)]
 impl<'lua> Table<'lua> {
     /// Sets a key-value pair in the table.
     ///
@@ -50,19 +59,15 @@ impl<'lua> Table<'lua> {
         let lua = self.0.lua;
         let key = key.to_lua(lua)?;
         let value = value.to_lua(lua)?;
+
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 6);
+            check_stack(lua.state, 6)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
             lua.push_value(value)?;
-
-            unsafe extern "C" fn set_table(state: *mut ffi::lua_State) -> c_int {
-                ffi::lua_settable(state, -3);
-                1
-            }
-            protect_lua(lua.state, 3, set_table)
+            ffi::safe::lua_settable(lua.state, -3)
         }
     }
 
@@ -93,18 +98,15 @@ impl<'lua> Table<'lua> {
     pub fn get<K: ToLua<'lua>, V: FromLua<'lua>>(&self, key: K) -> Result<V> {
         let lua = self.0.lua;
         let key = key.to_lua(lua)?;
+
         let value = unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 5);
+            check_stack(lua.state, 5)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
+            ffi::safe::lua_gettable(lua.state, -2)?;
 
-            unsafe extern "C" fn get_table(state: *mut ffi::lua_State) -> c_int {
-                ffi::lua_gettable(state, -2);
-                1
-            }
-            protect_lua(lua.state, 2, get_table)?;
             lua.pop_value()
         };
         V::from_lua(value, lua)
@@ -117,55 +119,16 @@ impl<'lua> Table<'lua> {
 
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 5);
+            check_stack(lua.state, 5)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
+            ffi::safe::lua_gettable(lua.state, -2)?;
 
-            unsafe extern "C" fn get_table(state: *mut ffi::lua_State) -> c_int {
-                ffi::lua_gettable(state, -2);
-                1
-            }
-            protect_lua(lua.state, 2, get_table)?;
-
-            let has = ffi::lua_isnil(lua.state, -1) == 0;
-            Ok(has)
+            Ok(ffi::lua_isnil(lua.state, -1) == 0)
         }
     }
 
-    /// Gets the function associated to `key` from the table and executes it,
-    /// passing the table itself as the first argument.
-    ///
-    /// # Examples
-    ///
-    /// Execute the table method with name "concat":
-    ///
-    /// ```
-    /// # use mlua::{Lua, Result, Table};
-    /// # fn main() -> Result<()> {
-    /// # let lua = Lua::new();
-    /// # let object = lua.create_table()?;
-    /// # let concat = lua.create_function(|_, (_, a, b): (Table, String, String)| Ok(a + &b))?;
-    /// # object.set("concat", concat)?;
-    /// // simiar to: object:concat("param1", "param2")
-    /// object.call("concat", ("param1", "param2"))?;
-    /// # Ok(())
-    /// # }
-    /// ```
-    ///
-    /// This might invoke the `__index` metamethod.
-    pub fn call<K, A, R>(&self, key: K, args: A) -> Result<R>
-    where
-        K: ToLua<'lua>,
-        A: ToLuaMulti<'lua>,
-        R: FromLuaMulti<'lua>,
-    {
-        let lua = self.0.lua;
-        let mut args = args.to_lua_multi(lua)?;
-        args.push_front(Value::Table(self.clone()));
-        self.get::<_, Function>(key)?.call(args)
-    }
-
     /// Compares two tables for equality.
     ///
     /// Tables are compared by reference first.
@@ -230,19 +193,12 @@ impl<'lua> Table<'lua> {
 
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 6);
+            check_stack(lua.state, 6)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
             lua.push_value(value)?;
-
-            unsafe extern "C" fn raw_set(state: *mut ffi::lua_State) -> c_int {
-                ffi::lua_rawset(state, -3);
-                0
-            }
-            protect_lua(lua.state, 3, raw_set)?;
-
-            Ok(())
+            ffi::safe::lua_rawset(lua.state, -3)
         }
     }
 
@@ -250,19 +206,21 @@ impl<'lua> Table<'lua> {
     pub fn raw_get<K: ToLua<'lua>, V: FromLua<'lua>>(&self, key: K) -> Result<V> {
         let lua = self.0.lua;
         let key = key.to_lua(lua)?;
+
         let value = unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 3);
+            check_stack(lua.state, 3)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
             ffi::lua_rawget(lua.state, -2);
+
             lua.pop_value()
         };
         V::from_lua(value, lua)
     }
 
-    /// Inserts element value at position idx to the table, shifting up the elements from table[idx].
+    /// Inserts element value at position `idx` to the table, shifting up the elements from `table[idx]`.
     /// The worst case complexity is O(n), where n is the table length.
     pub fn raw_insert<V: ToLua<'lua>>(&self, idx: Integer, value: V) -> Result<()> {
         let lua = self.0.lua;
@@ -274,29 +232,21 @@ impl<'lua> Table<'lua> {
         let value = value.to_lua(lua)?;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 6);
+            check_stack(lua.state, 6)?;
 
             lua.push_ref(&self.0);
             lua.push_value(value)?;
-
-            protect_lua_closure(lua.state, 2, 0, |state| {
-                for i in (idx..size + 1).rev() {
-                    // table[i+1] = table[i]
-                    ffi::lua_rawgeti(state, -2, i);
-                    ffi::lua_rawseti(state, -3, i + 1);
-                }
-                ffi::lua_rawseti(state, -2, idx);
-            })
+            ffi::safe::lua_rawinsert(lua.state, -2, idx)
         }
     }
 
     /// Removes a key from the table.
     ///
-    /// If `key` is an integer, mlua shifts down the elements from table[key+1],
-    /// and erases element table[key]. The complexity is O(n) in worst case,
+    /// If `key` is an integer, mlua shifts down the elements from `table[key+1]`,
+    /// and erases element `table[key]`. The complexity is O(n) in worst case,
     /// where n is the table length.
     ///
-    /// For othey key types this is equivalent to setting table[key] = nil.
+    /// For othey key types this is equivalent to setting `table[key] = nil`.
     pub fn raw_remove<K: ToLua<'lua>>(&self, key: K) -> Result<()> {
         let lua = self.0.lua;
         let key = key.to_lua(lua)?;
@@ -308,18 +258,10 @@ impl<'lua> Table<'lua> {
                 }
                 unsafe {
                     let _sg = StackGuard::new(lua.state);
-                    assert_stack(lua.state, 6);
+                    check_stack(lua.state, 5)?;
 
                     lua.push_ref(&self.0);
-
-                    protect_lua_closure(lua.state, 1, 0, |state| {
-                        for i in idx..size {
-                            ffi::lua_rawgeti(state, -1, i + 1);
-                            ffi::lua_rawseti(state, -2, i);
-                        }
-                        ffi::lua_pushnil(state);
-                        ffi::lua_rawseti(state, -2, size);
-                    })
+                    ffi::safe::lua_rawremove(lua.state, -1, idx)
                 }
             }
             _ => self.raw_set(key, Nil),
@@ -335,9 +277,10 @@ impl<'lua> Table<'lua> {
         let lua = self.0.lua;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 4);
+            check_stack(lua.state, 4)?;
+
             lua.push_ref(&self.0);
-            protect_lua_closure(lua.state, 1, 0, |state| ffi::luaL_len(state, -1))
+            ffi::safe::luaL_len(lua.state, -1)
         }
     }
 
@@ -347,9 +290,9 @@ impl<'lua> Table<'lua> {
         unsafe {
             let _sg = StackGuard::new(lua.state);
             assert_stack(lua.state, 1);
+
             lua.push_ref(&self.0);
-            let len = ffi::lua_rawlen(lua.state, -1);
-            len as Integer
+            ffi::lua_rawlen(lua.state, -1) as Integer
         }
     }
 
@@ -360,13 +303,13 @@ impl<'lua> Table<'lua> {
         let lua = self.0.lua;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 1);
+            assert_stack(lua.state, 2);
+
             lua.push_ref(&self.0);
             if ffi::lua_getmetatable(lua.state, -1) == 0 {
                 None
             } else {
-                let table = Table(lua.pop_ref());
-                Some(table)
+                Some(Table(lua.pop_ref()))
             }
         }
     }
@@ -379,7 +322,8 @@ impl<'lua> Table<'lua> {
         let lua = self.0.lua;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 1);
+            assert_stack(lua.state, 2);
+
             lua.push_ref(&self.0);
             if let Some(metatable) = metatable {
                 lua.push_ref(&metatable.0);
@@ -426,7 +370,7 @@ impl<'lua> Table<'lua> {
     pub fn pairs<K: FromLua<'lua>, V: FromLua<'lua>>(self) -> TablePairs<'lua, K, V> {
         TablePairs {
             table: self.0,
-            next_key: Some(Nil),
+            key: Some(Nil),
             _phantom: PhantomData,
         }
     }
@@ -476,9 +420,57 @@ impl<'lua> Table<'lua> {
         TableSequence {
             table: self.0,
             index: Some(1),
+            len: None,
+            raw: false,
             _phantom: PhantomData,
         }
     }
+
+    /// Consume this table and return an iterator over all values in the sequence part of the table.
+    ///
+    /// Unlike the `sequence_values`, does not invoke `__index` metamethod when iterating.
+    ///
+    /// [`sequence_values`]: #method.sequence_values
+    pub fn raw_sequence_values<V: FromLua<'lua>>(self) -> TableSequence<'lua, V> {
+        TableSequence {
+            table: self.0,
+            index: Some(1),
+            len: None,
+            raw: true,
+            _phantom: PhantomData,
+        }
+    }
+
+    #[cfg(any(feature = "async", feature = "serialize"))]
+    pub(crate) fn raw_sequence_values_by_len<V: FromLua<'lua>>(
+        self,
+        len: Option<Integer>,
+    ) -> TableSequence<'lua, V> {
+        let len = len.unwrap_or_else(|| self.raw_len());
+        TableSequence {
+            table: self.0,
+            index: Some(1),
+            len: Some(len),
+            raw: true,
+            _phantom: PhantomData,
+        }
+    }
+
+    #[cfg(feature = "serialize")]
+    pub(crate) fn is_array(&self) -> bool {
+        let lua = self.0.lua;
+        unsafe {
+            let _sg = StackGuard::new(lua.state);
+            assert_stack(lua.state, 3);
+
+            lua.push_ref(&self.0);
+            if ffi::lua_getmetatable(lua.state, -1) == 0 {
+                return false;
+            }
+            crate::serde::push_array_metatable(lua.state);
+            ffi::lua_rawequal(lua.state, -1, -2) != 0
+        }
+    }
 }
 
 impl<'lua> PartialEq for Table<'lua> {
@@ -494,6 +486,148 @@ impl<'lua> AsRef<Table<'lua>> for Table<'lua> {
     }
 }
 
+/// An extension trait for `Table`s that provides a variety of convenient functionality.
+pub trait TableExt<'lua> {
+    /// Gets the function associated to `key` from the table and executes it,
+    /// passing the table itself along with `args` as function arguments.
+    ///
+    /// This is a shortcut for
+    /// `table.get::<_, Function>(key)?.call((table.clone(), arg1, ..., argN))`
+    ///
+    /// This might invoke the `__index` metamethod.
+    fn call_method<K, A, R>(&self, key: K, args: A) -> Result<R>
+    where
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua>;
+
+    /// Gets the function associated to `key` from the table and executes it,
+    /// passing `args` as function arguments.
+    ///
+    /// This is a shortcut for
+    /// `table.get::<_, Function>(key)?.call(args)`
+    ///
+    /// This might invoke the `__index` metamethod.
+    fn call_function<K, A, R>(&self, key: K, args: A) -> Result<R>
+    where
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua>;
+
+    /// Gets the function associated to `key` from the table and asynchronously executes it,
+    /// passing the table itself along with `args` as function arguments and returning Future.
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// This might invoke the `__index` metamethod.
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    fn call_async_method<'fut, K, A, R>(&self, key: K, args: A) -> LocalBoxFuture<'fut, Result<R>>
+    where
+        'lua: 'fut,
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua> + 'fut;
+
+    /// Gets the function associated to `key` from the table and asynchronously executes it,
+    /// passing `args` as function arguments and returning Future.
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// This might invoke the `__index` metamethod.
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    fn call_async_function<'fut, K, A, R>(
+        &self,
+        key: K,
+        args: A,
+    ) -> LocalBoxFuture<'fut, Result<R>>
+    where
+        'lua: 'fut,
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua> + 'fut;
+}
+
+impl<'lua> TableExt<'lua> for Table<'lua> {
+    fn call_method<K, A, R>(&self, key: K, args: A) -> Result<R>
+    where
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua>,
+    {
+        let lua = self.0.lua;
+        let mut args = args.to_lua_multi(lua)?;
+        args.push_front(Value::Table(self.clone()));
+        self.get::<_, Function>(key)?.call(args)
+    }
+
+    fn call_function<K, A, R>(&self, key: K, args: A) -> Result<R>
+    where
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua>,
+    {
+        self.get::<_, Function>(key)?.call(args)
+    }
+
+    #[cfg(feature = "async")]
+    fn call_async_method<'fut, K, A, R>(&self, key: K, args: A) -> LocalBoxFuture<'fut, Result<R>>
+    where
+        'lua: 'fut,
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua> + 'fut,
+    {
+        let lua = self.0.lua;
+        let mut args = match args.to_lua_multi(lua) {
+            Ok(args) => args,
+            Err(e) => return Box::pin(future::err(e)),
+        };
+        args.push_front(Value::Table(self.clone()));
+        self.call_async_function(key, args)
+    }
+
+    #[cfg(feature = "async")]
+    fn call_async_function<'fut, K, A, R>(&self, key: K, args: A) -> LocalBoxFuture<'fut, Result<R>>
+    where
+        'lua: 'fut,
+        K: ToLua<'lua>,
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua> + 'fut,
+    {
+        match self.get::<_, Function>(key) {
+            Ok(func) => func.call_async(args),
+            Err(e) => Box::pin(future::err(e)),
+        }
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl<'lua> Serialize for Table<'lua> {
+    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let len = self.raw_len() as usize;
+        if len > 0 || self.is_array() {
+            let mut seq = serializer.serialize_seq(Some(len))?;
+            for v in self.clone().raw_sequence_values_by_len::<Value>(None) {
+                let v = v.map_err(serde::ser::Error::custom)?;
+                seq.serialize_element(&v)?;
+            }
+            return seq.end();
+        }
+
+        let mut map = serializer.serialize_map(None)?;
+        for kv in self.clone().pairs::<Value, Value>() {
+            let (k, v) = kv.map_err(serde::ser::Error::custom)?;
+            map.serialize_entry(&k, &v)?;
+        }
+        map.end()
+    }
+}
+
 /// An iterator over the pairs of a Lua table.
 ///
 /// This struct is created by the [`Table::pairs`] method.
@@ -501,7 +635,7 @@ impl<'lua> AsRef<Table<'lua>> for Table<'lua> {
 /// [`Table::pairs`]: struct.Table.html#method.pairs
 pub struct TablePairs<'lua, K, V> {
     table: LuaRef<'lua>,
-    next_key: Option<Value<'lua>>,
+    key: Option<Value<'lua>>,
     _phantom: PhantomData<(K, V)>,
 }
 
@@ -513,40 +647,34 @@ where
     type Item = Result<(K, V)>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        if let Some(next_key) = self.next_key.take() {
+        if let Some(prev_key) = self.key.take() {
             let lua = self.table.lua;
 
-            let res = (|| {
-                let res = unsafe {
-                    let _sg = StackGuard::new(lua.state);
-                    assert_stack(lua.state, 6);
+            let res = (|| unsafe {
+                let _sg = StackGuard::new(lua.state);
+                check_stack(lua.state, 5)?;
 
-                    lua.push_ref(&self.table);
-                    lua.push_value(next_key)?;
+                lua.push_ref(&self.table);
+                lua.push_value(prev_key)?;
 
-                    if protect_lua_closure(lua.state, 2, ffi::LUA_MULTRET, |state| {
-                        ffi::lua_next(state, -2) != 0
-                    })? {
-                        ffi::lua_pushvalue(lua.state, -2);
-                        let key = lua.pop_value();
-                        let value = lua.pop_value();
-                        self.next_key = Some(lua.pop_value());
-
-                        Some((key, value))
-                    } else {
-                        None
-                    }
-                };
-
-                Ok(if let Some((key, value)) = res {
-                    Some((K::from_lua(key, lua)?, V::from_lua(value, lua)?))
+                if ffi::safe::lua_next(lua.state, -2)? != 0 {
+                    let value = lua.pop_value();
+                    let key = lua.pop_value();
+                    Ok(Some((
+                        key.clone(),
+                        K::from_lua(key, lua)?,
+                        V::from_lua(value, lua)?,
+                    )))
                 } else {
-                    None
-                })
+                    Ok(None)
+                }
             })();
 
             match res {
-                Ok(Some((key, value))) => Some(Ok((key, value))),
+                Ok(Some((key, ret_key, value))) => {
+                    self.key = Some(key);
+                    Some(Ok((ret_key, value)))
+                }
                 Ok(None) => None,
                 Err(e) => Some(Err(e)),
             }
@@ -564,6 +692,8 @@ where
 pub struct TableSequence<'lua, V> {
     table: LuaRef<'lua>,
     index: Option<Integer>,
+    len: Option<Integer>,
+    raw: bool,
     _phantom: PhantomData<V>,
 }
 
@@ -577,27 +707,29 @@ where
         if let Some(index) = self.index.take() {
             let lua = self.table.lua;
 
-            let res = unsafe {
+            let res = (|| unsafe {
                 let _sg = StackGuard::new(lua.state);
-                assert_stack(lua.state, 5);
+                check_stack(lua.state, 1 + if self.raw { 0 } else { 4 })?;
 
                 lua.push_ref(&self.table);
-                match protect_lua_closure(lua.state, 1, 1, |state| ffi::lua_geti(state, -1, index))
-                {
-                    Ok(ffi::LUA_TNIL) => None,
-                    Ok(_) => {
-                        let value = lua.pop_value();
-                        self.index = Some(index + 1);
-                        Some(Ok(value))
-                    }
-                    Err(err) => Some(Err(err)),
+                let res = if self.raw {
+                    ffi::lua_rawgeti(lua.state, -1, index)
+                } else {
+                    ffi::safe::lua_geti(lua.state, -1, index)?
+                };
+                match res {
+                    ffi::LUA_TNIL if index > self.len.unwrap_or(0) => Ok(None),
+                    _ => Ok(Some((index, lua.pop_value()))),
                 }
-            };
+            })();
 
             match res {
-                Some(Ok(r)) => Some(V::from_lua(r, lua)),
-                Some(Err(err)) => Some(Err(err)),
-                None => None,
+                Ok(Some((index, r))) => {
+                    self.index = Some(index + 1);
+                    Some(V::from_lua(r, lua))
+                }
+                Ok(None) => None,
+                Err(err) => Some(Err(err)),
             }
         } else {
             None

src/thread.rs

@@ -1,13 +1,30 @@
+use std::cmp;
 use std::os::raw::c_int;
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::types::LuaRef;
-use crate::util::{
-    assert_stack, check_stack, error_traceback, pop_error, protect_lua_closure, StackGuard,
-};
+use crate::util::{assert_stack, check_stack, pop_error, StackGuard};
 use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
 
+#[cfg(feature = "async")]
+use {
+    crate::{
+        lua::{ASYNC_POLL_PENDING, WAKER_REGISTRY_KEY},
+        util::get_gc_userdata,
+        value::Value,
+    },
+    futures_core::{future::Future, stream::Stream},
+    std::{
+        cell::RefCell,
+        marker::PhantomData,
+        mem,
+        os::raw::c_void,
+        pin::Pin,
+        task::{Context, Poll, Waker},
+    },
+};
+
 /// Status of a Lua thread (or coroutine).
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum ThreadStatus {
@@ -27,6 +44,21 @@ pub enum ThreadStatus {
 #[derive(Clone, Debug)]
 pub struct Thread<'lua>(pub(crate) LuaRef<'lua>);
 
+/// Thread (coroutine) representation as an async [`Future`] or [`Stream`].
+///
+/// Requires `feature = "async"`
+///
+/// [`Future`]: ../futures_core/future/trait.Future.html
+/// [`Stream`]: ../futures_core/stream/trait.Stream.html
+#[cfg(feature = "async")]
+#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+#[derive(Debug)]
+pub struct AsyncThread<'lua, R> {
+    thread: Thread<'lua>,
+    args0: RefCell<Option<Result<MultiValue<'lua>>>>,
+    ret: PhantomData<R>,
+}
+
 impl<'lua> Thread<'lua> {
     /// Resumes execution of this thread.
     ///
@@ -76,43 +108,38 @@ impl<'lua> Thread<'lua> {
     {
         let lua = self.0.lua;
         let args = args.to_lua_multi(lua)?;
+        let nargs = args.len() as c_int;
         let results = unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 3);
+            check_stack(lua.state, cmp::min(nargs + 1, 3))?;
 
             lua.push_ref(&self.0);
             let thread_state = ffi::lua_tothread(lua.state, -1);
+            ffi::lua_pop(lua.state, 1);
 
             let status = ffi::lua_status(thread_state);
             if status != ffi::LUA_YIELD && ffi::lua_gettop(thread_state) == 0 {
                 return Err(Error::CoroutineInactive);
             }
 
-            ffi::lua_pop(lua.state, 1);
-
-            let nargs = args.len() as c_int;
-            check_stack(lua.state, nargs)?;
-            check_stack(thread_state, nargs + 1)?;
-
+            check_stack(thread_state, nargs)?;
             for arg in args {
                 lua.push_value(arg)?;
             }
             ffi::lua_xmove(lua.state, thread_state, nargs);
 
-            let ret = ffi::lua_resume(thread_state, lua.state, nargs);
+            let mut nresults = 0;
+
+            let ret = ffi::lua_resume(thread_state, lua.state, nargs, &mut nresults as *mut c_int);
             if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
-                protect_lua_closure(lua.state, 0, 0, |_| {
-                    error_traceback(thread_state);
-                    0
-                })?;
+                ffi::safe::error_traceback2(lua.state, thread_state)?;
                 return Err(pop_error(thread_state, ret));
             }
 
-            let nresults = ffi::lua_gettop(thread_state);
             let mut results = MultiValue::new();
+            check_stack(lua.state, nresults + 2)?; // 2 is extra for `lua.pop_value()` below
             ffi::lua_xmove(thread_state, lua.state, nresults);
 
-            assert_stack(lua.state, 2);
             for _ in 0..nresults {
                 results.push_front(lua.pop_value());
             }
@@ -142,6 +169,62 @@ impl<'lua> Thread<'lua> {
             }
         }
     }
+
+    /// Converts Thread to an AsyncThread which implements Future and Stream traits.
+    ///
+    /// `args` are passed as arguments to the thread function for first call.
+    /// The object call `resume()` while polling and also allows to run rust futures
+    /// to completion using an executor.
+    ///
+    /// Using AsyncThread as a Stream allows to iterate through `coroutine.yield()`
+    /// values whereas Future version discards that values and poll until the final
+    /// one (returned from the thread function).
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use mlua::{Lua, Result, Thread};
+    /// use futures::stream::TryStreamExt;
+    /// # #[tokio::main]
+    /// # async fn main() -> Result<()> {
+    /// # let lua = Lua::new();
+    /// let thread: Thread = lua.load(r#"
+    ///     coroutine.create(function (sum)
+    ///         for i = 1,10 do
+    ///             sum = sum + i
+    ///             coroutine.yield(sum)
+    ///         end
+    ///         return sum
+    ///     end)
+    /// "#).eval()?;
+    ///
+    /// let mut stream = thread.into_async::<_, i64>(1);
+    /// let mut sum = 0;
+    /// while let Some(n) = stream.try_next().await? {
+    ///     sum += n;
+    /// }
+    ///
+    /// assert_eq!(sum, 286);
+    ///
+    /// # Ok(())
+    /// # }
+    /// ```
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    pub fn into_async<A, R>(self, args: A) -> AsyncThread<'lua, R>
+    where
+        A: ToLuaMulti<'lua>,
+        R: FromLuaMulti<'lua>,
+    {
+        let args = args.to_lua_multi(&self.0.lua);
+        AsyncThread {
+            thread: self,
+            args0: RefCell::new(Some(args)),
+            ret: PhantomData,
+        }
+    }
 }
 
 impl<'lua> PartialEq for Thread<'lua> {
@@ -149,3 +232,116 @@ impl<'lua> PartialEq for Thread<'lua> {
         self.0 == other.0
     }
 }
+
+#[cfg(feature = "async")]
+impl<'lua, R> Stream for AsyncThread<'lua, R>
+where
+    R: FromLuaMulti<'lua>,
+{
+    type Item = Result<R>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let lua = self.thread.0.lua;
+
+        match self.thread.status() {
+            ThreadStatus::Resumable => {}
+            _ => return Poll::Ready(None),
+        };
+
+        let _wg = WakerGuard::new(lua.state, cx.waker().clone());
+        let ret: MultiValue = if let Some(args) = self.args0.borrow_mut().take() {
+            self.thread.resume(args?)?
+        } else {
+            self.thread.resume(())?
+        };
+
+        if is_poll_pending(&ret) {
+            return Poll::Pending;
+        }
+
+        cx.waker().wake_by_ref();
+        Poll::Ready(Some(R::from_lua_multi(ret, lua)))
+    }
+}
+
+#[cfg(feature = "async")]
+impl<'lua, R> Future for AsyncThread<'lua, R>
+where
+    R: FromLuaMulti<'lua>,
+{
+    type Output = Result<R>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let lua = self.thread.0.lua;
+
+        match self.thread.status() {
+            ThreadStatus::Resumable => {}
+            _ => return Poll::Ready(Err(Error::CoroutineInactive)),
+        };
+
+        let _wg = WakerGuard::new(lua.state, cx.waker().clone());
+        let ret: MultiValue = if let Some(args) = self.args0.borrow_mut().take() {
+            self.thread.resume(args?)?
+        } else {
+            self.thread.resume(())?
+        };
+
+        if is_poll_pending(&ret) {
+            return Poll::Pending;
+        }
+
+        if let ThreadStatus::Resumable = self.thread.status() {
+            // Ignore value returned via yield()
+            cx.waker().wake_by_ref();
+            return Poll::Pending;
+        }
+
+        Poll::Ready(R::from_lua_multi(ret, lua))
+    }
+}
+
+#[cfg(feature = "async")]
+fn is_poll_pending(val: &MultiValue) -> bool {
+    match val.iter().enumerate().last() {
+        Some((1, Value::LightUserData(ud))) => {
+            ud.0 == &ASYNC_POLL_PENDING as *const u8 as *mut c_void
+        }
+        _ => false,
+    }
+}
+
+#[cfg(feature = "async")]
+struct WakerGuard(*mut ffi::lua_State, Option<Waker>);
+
+#[cfg(feature = "async")]
+impl WakerGuard {
+    pub fn new(state: *mut ffi::lua_State, waker: Waker) -> Result<WakerGuard> {
+        unsafe {
+            let _sg = StackGuard::new(state);
+            check_stack(state, 3)?;
+
+            let waker_key = &WAKER_REGISTRY_KEY as *const u8 as *const c_void;
+            ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, waker_key);
+            let waker_slot = get_gc_userdata::<Option<Waker>>(state, -1).as_mut();
+            let old = mlua_expect!(waker_slot, "Waker is destroyed").replace(waker);
+
+            Ok(WakerGuard(state, old))
+        }
+    }
+}
+
+#[cfg(feature = "async")]
+impl Drop for WakerGuard {
+    fn drop(&mut self) {
+        let state = self.0;
+        unsafe {
+            let _sg = StackGuard::new(state);
+            assert_stack(state, 3);
+
+            let waker_key = &WAKER_REGISTRY_KEY as *const u8 as *const c_void;
+            ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, waker_key);
+            let waker_slot = get_gc_userdata::<Option<Waker>>(state, -1).as_mut();
+            mem::swap(mlua_expect!(waker_slot, "Waker is destroyed"), &mut self.1);
+        }
+    }
+}

src/types.rs

@@ -1,9 +1,14 @@
+use std::cell::RefCell;
 use std::os::raw::{c_int, c_void};
 use std::sync::{Arc, Mutex};
 use std::{fmt, mem, ptr};
 
+#[cfg(feature = "async")]
+use futures_core::future::LocalBoxFuture;
+
 use crate::error::Result;
 use crate::ffi;
+use crate::hook::Debug;
 use crate::lua::Lua;
 use crate::util::{assert_stack, StackGuard};
 use crate::value::MultiValue;
@@ -20,24 +25,35 @@ pub struct LightUserData(pub *mut c_void);
 pub(crate) type Callback<'lua, 'a> =
     Box<dyn Fn(&'lua Lua, MultiValue<'lua>) -> Result<MultiValue<'lua>> + 'a>;
 
+#[cfg(feature = "async")]
+pub(crate) type AsyncCallback<'lua, 'a> =
+    Box<dyn Fn(&'lua Lua, MultiValue<'lua>) -> LocalBoxFuture<'lua, Result<MultiValue<'lua>>> + 'a>;
+
+pub(crate) type HookCallback = Arc<RefCell<dyn FnMut(&Lua, Debug) -> Result<()>>>;
+
+#[cfg(feature = "send")]
+pub trait MaybeSend: Send {}
+#[cfg(feature = "send")]
+impl<T: Send> MaybeSend for T {}
+
+#[cfg(not(feature = "send"))]
+pub trait MaybeSend {}
+#[cfg(not(feature = "send"))]
+impl<T> MaybeSend for T {}
+
 /// An auto generated key into the Lua registry.
 ///
-/// This is a handle to a value stored inside the Lua registry.  It is not directly usable like the
-/// `Table` or `Function` handle types, but since it doesn't hold a reference to a parent Lua and is
-/// Send + Sync + 'static, it is much more flexible and can be used in many situations where it is
-/// impossible to directly store a normal handle type.  It is not automatically garbage collected on
-/// Drop, but it can be removed with [`Lua::remove_registry_value`], and instances not manually
-/// removed can be garbage collected with [`Lua::expire_registry_values`].
+/// This is a handle to a value stored inside the Lua registry. It is not automatically
+/// garbage collected on Drop, but it can be removed with [`Lua::remove_registry_value`],
+/// and instances not manually removed can be garbage collected with [`Lua::expire_registry_values`].
 ///
 /// Be warned, If you place this into Lua via a `UserData` type or a rust callback, it is *very
 /// easy* to accidentally cause reference cycles that the Lua garbage collector cannot resolve.
 /// Instead of placing a `RegistryKey` into a `UserData` type, prefer instead to use
-/// [`UserData::set_user_value`] / [`UserData::get_user_value`], and instead of moving a RegistryKey
-/// into a callback, prefer [`Lua::scope`].
+/// [`UserData::set_user_value`] / [`UserData::get_user_value`].
 ///
 /// [`Lua::remove_registry_value`]: struct.Lua.html#method.remove_registry_value
 /// [`Lua::expire_registry_values`]: struct.Lua.html#method.expire_registry_values
-/// [`Lua::scope`]: struct.Lua.html#method.scope
 /// [`UserData::set_user_value`]: struct.UserData.html#method.set_user_value
 /// [`UserData::get_user_value`]: struct.UserData.html#method.get_user_value
 pub struct RegistryKey {
@@ -53,7 +69,8 @@ impl fmt::Debug for RegistryKey {
 
 impl Drop for RegistryKey {
     fn drop(&mut self) {
-        if let Some(list) = mlua_expect!(self.unref_list.lock(), "unref_list poisoned").as_mut() {
+        let mut unref_list = mlua_expect!(self.unref_list.lock(), "unref list poisoned");
+        if let Some(list) = unref_list.as_mut() {
             list.push(self.registry_id);
         }
     }

src/userdata.rs

@@ -1,13 +1,27 @@
 use std::cell::{Ref, RefCell, RefMut};
+use std::fmt;
+use std::hash::{Hash, Hasher};
+use std::ops::Deref;
+use std::string::String as StdString;
+use std::sync::Arc;
+
+#[cfg(feature = "async")]
+use std::future::Future;
+
+#[cfg(feature = "serialize")]
+use {
+    serde::ser::{self, Serialize, Serializer},
+    std::result::Result as StdResult,
+};
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::function::Function;
 use crate::lua::Lua;
-use crate::table::Table;
-use crate::types::LuaRef;
-use crate::util::{assert_stack, get_userdata, StackGuard};
-use crate::value::{FromLua, FromLuaMulti, ToLua, ToLuaMulti};
+use crate::table::{Table, TablePairs};
+use crate::types::{LuaRef, MaybeSend};
+use crate::util::{check_stack, get_destructed_userdata_metatable, get_userdata, StackGuard};
+use crate::value::{FromLua, FromLuaMulti, ToLua, ToLuaMulti, Value};
 
 /// Kinds of metamethods that can be overridden.
 ///
@@ -15,7 +29,7 @@ use crate::value::{FromLua, FromLuaMulti, ToLua, ToLuaMulti};
 /// generally no need to do so: [`UserData`] implementors can instead just implement `Drop`.
 ///
 /// [`UserData`]: trait.UserData.html
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+#[derive(Debug, Clone)]
 pub enum MetaMethod {
     /// The `+` operator.
     Add,
@@ -31,26 +45,31 @@ pub enum MetaMethod {
     Pow,
     /// The unary minus (`-`) operator.
     Unm,
-    #[cfg(feature = "lua53")]
     /// The floor division (//) operator.
+    /// Requires `feature = "lua54/lua53"`
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     IDiv,
-    #[cfg(feature = "lua53")]
     /// The bitwise AND (&) operator.
+    /// Requires `feature = "lua54/lua53"`
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     BAnd,
-    #[cfg(feature = "lua53")]
     /// The bitwise OR (|) operator.
+    /// Requires `feature = "lua54/lua53"`
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     BOr,
-    #[cfg(feature = "lua53")]
     /// The bitwise XOR (binary ~) operator.
+    /// Requires `feature = "lua54/lua53"`
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     BXor,
-    #[cfg(feature = "lua53")]
     /// The bitwise NOT (unary ~) operator.
+    /// Requires `feature = "lua54/lua53"`
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     BNot,
-    #[cfg(feature = "lua53")]
     /// The bitwise left shift (<<) operator.
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     Shl,
-    #[cfg(feature = "lua53")]
     /// The bitwise right shift (>>) operator.
+    #[cfg(any(feature = "lua54", feature = "lua53", doc))]
     Shr,
     /// The string concatenation operator `..`.
     Concat,
@@ -72,57 +91,170 @@ pub enum MetaMethod {
     ///
     /// This is not an operator, but will be called by methods such as `tostring` and `print`.
     ToString,
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
     /// The `__pairs` metamethod.
     ///
     /// This is not an operator, but it will be called by the built-in `pairs` function.
+    ///
+    /// Requires `feature = "lua54/lua53/lua52"`
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", doc))]
     Pairs,
+    /// The `__close` metamethod.
+    ///
+    /// Executed when a variable, that marked as to-be-closed, goes out of scope.
+    ///
+    /// More information about to-be-closed variabled can be found in the Lua 5.4
+    /// [documentation][lua_doc].
+    ///
+    /// Requires `feature = "lua54"`
+    ///
+    /// [lua_doc]: https://www.lua.org/manual/5.4/manual.html#3.3.8
+    #[cfg(any(feature = "lua54", doc))]
+    Close,
+    /// A custom metamethod.
+    ///
+    /// Must not be in the protected list: `__gc`, `__metatable`, `__mlua*`.
+    Custom(StdString),
+}
+
+impl PartialEq for MetaMethod {
+    fn eq(&self, other: &Self) -> bool {
+        self.name() == other.name()
+    }
+}
+
+impl Eq for MetaMethod {}
+
+impl Hash for MetaMethod {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.name().hash(state);
+    }
+}
+
+impl fmt::Display for MetaMethod {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "{}", self.name())
+    }
 }
 
 impl MetaMethod {
-    pub(crate) fn name(self) -> &'static [u8] {
+    /// Returns Lua metamethod name, usually prefixed by two underscores.
+    pub fn name(&self) -> &str {
         match self {
-            MetaMethod::Add => b"__add",
-            MetaMethod::Sub => b"__sub",
-            MetaMethod::Mul => b"__mul",
-            MetaMethod::Div => b"__div",
-            MetaMethod::Mod => b"__mod",
-            MetaMethod::Pow => b"__pow",
-            MetaMethod::Unm => b"__unm",
-            #[cfg(feature = "lua53")]
-            MetaMethod::IDiv => b"__idiv",
-            #[cfg(feature = "lua53")]
-            MetaMethod::BAnd => b"__band",
-            #[cfg(feature = "lua53")]
-            MetaMethod::BOr => b"__bor",
-            #[cfg(feature = "lua53")]
-            MetaMethod::BXor => b"__bxor",
-            #[cfg(feature = "lua53")]
-            MetaMethod::BNot => b"__bnot",
-            #[cfg(feature = "lua53")]
-            MetaMethod::Shl => b"__shl",
-            #[cfg(feature = "lua53")]
-            MetaMethod::Shr => b"__shr",
-            MetaMethod::Concat => b"__concat",
-            MetaMethod::Len => b"__len",
-            MetaMethod::Eq => b"__eq",
-            MetaMethod::Lt => b"__lt",
-            MetaMethod::Le => b"__le",
-            MetaMethod::Index => b"__index",
-            MetaMethod::NewIndex => b"__newindex",
-            MetaMethod::Call => b"__call",
-            MetaMethod::ToString => b"__tostring",
-            #[cfg(any(feature = "lua53", feature = "lua52"))]
-            MetaMethod::Pairs => b"__pairs",
+            MetaMethod::Add => "__add",
+            MetaMethod::Sub => "__sub",
+            MetaMethod::Mul => "__mul",
+            MetaMethod::Div => "__div",
+            MetaMethod::Mod => "__mod",
+            MetaMethod::Pow => "__pow",
+            MetaMethod::Unm => "__unm",
+
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::IDiv => "__idiv",
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::BAnd => "__band",
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::BOr => "__bor",
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::BXor => "__bxor",
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::BNot => "__bnot",
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::Shl => "__shl",
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            MetaMethod::Shr => "__shr",
+
+            MetaMethod::Concat => "__concat",
+            MetaMethod::Len => "__len",
+            MetaMethod::Eq => "__eq",
+            MetaMethod::Lt => "__lt",
+            MetaMethod::Le => "__le",
+            MetaMethod::Index => "__index",
+            MetaMethod::NewIndex => "__newindex",
+            MetaMethod::Call => "__call",
+            MetaMethod::ToString => "__tostring",
+
+            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+            MetaMethod::Pairs => "__pairs",
+
+            #[cfg(feature = "lua54")]
+            MetaMethod::Close => "__close",
+
+            MetaMethod::Custom(ref name) => name,
         }
     }
+
+    pub(crate) fn validate(self) -> Result<Self> {
+        match self {
+            MetaMethod::Custom(name) if name == "__gc" => Err(Error::MetaMethodRestricted(name)),
+            MetaMethod::Custom(name) if name == "__metatable" => {
+                Err(Error::MetaMethodRestricted(name))
+            }
+            MetaMethod::Custom(name) if name.starts_with("__mlua") => {
+                Err(Error::MetaMethodRestricted(name))
+            }
+            _ => Ok(self),
+        }
+    }
+}
+
+impl From<StdString> for MetaMethod {
+    fn from(name: StdString) -> Self {
+        match name.as_str() {
+            "__add" => MetaMethod::Add,
+            "__sub" => MetaMethod::Sub,
+            "__mul" => MetaMethod::Mul,
+            "__div" => MetaMethod::Div,
+            "__mod" => MetaMethod::Mod,
+            "__pow" => MetaMethod::Pow,
+            "__unm" => MetaMethod::Unm,
+
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__idiv" => MetaMethod::IDiv,
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__band" => MetaMethod::BAnd,
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__bor" => MetaMethod::BOr,
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__bxor" => MetaMethod::BXor,
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__bnot" => MetaMethod::BNot,
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__shl" => MetaMethod::Shl,
+            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            "__shr" => MetaMethod::Shr,
+
+            "__concat" => MetaMethod::Concat,
+            "__len" => MetaMethod::Len,
+            "__eq" => MetaMethod::Eq,
+            "__lt" => MetaMethod::Lt,
+            "__le" => MetaMethod::Le,
+            "__index" => MetaMethod::Index,
+            "__newindex" => MetaMethod::NewIndex,
+            "__call" => MetaMethod::Call,
+            "__tostring" => MetaMethod::ToString,
+
+            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+            "__pairs" => MetaMethod::Pairs,
+
+            #[cfg(feature = "lua54")]
+            "__close" => MetaMethod::Close,
+
+            _ => MetaMethod::Custom(name),
+        }
+    }
+}
+
+impl From<&str> for MetaMethod {
+    fn from(name: &str) -> Self {
+        MetaMethod::from(name.to_owned())
+    }
 }
 
 /// Method registry for [`UserData`] implementors.
 ///
 /// [`UserData`]: trait.UserData.html
 pub trait UserDataMethods<'lua, T: UserData> {
-    /// Add a method which accepts a `&T` as the first parameter.
+    /// Add a regular method which accepts a `&T` as the first parameter.
     ///
     /// Regular methods are implemented by overriding the `__index` metamethod and returning the
     /// accessed method. This allows them to be used with the expected `userdata:method()` syntax.
@@ -131,10 +263,10 @@ pub trait UserDataMethods<'lua, T: UserData> {
     /// be used as a fall-back if no regular method is found.
     fn add_method<S, A, R, M>(&mut self, name: &S, method: M)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + Fn(&'lua Lua, &T, A) -> Result<R>;
+        M: 'static + MaybeSend + Fn(&'lua Lua, &T, A) -> Result<R>;
 
     /// Add a regular method which accepts a `&mut T` as the first parameter.
     ///
@@ -143,26 +275,46 @@ pub trait UserDataMethods<'lua, T: UserData> {
     /// [`add_method`]: #method.add_method
     fn add_method_mut<S, A, R, M>(&mut self, name: &S, method: M)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + FnMut(&'lua Lua, &mut T, A) -> Result<R>;
+        M: 'static + MaybeSend + FnMut(&'lua Lua, &mut T, A) -> Result<R>;
+
+    /// Add an async method which accepts a `T` as the first parameter and returns Future.
+    /// The passed `T` is cloned from the original value.
+    ///
+    /// Refer to [`add_method`] for more information about the implementation.
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// [`add_method`]: #method.add_method
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    fn add_async_method<S, A, R, M, MR>(&mut self, name: &S, method: M)
+    where
+        T: Clone,
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLuaMulti<'lua>,
+        R: ToLuaMulti<'lua>,
+        M: 'static + MaybeSend + Fn(&'lua Lua, T, A) -> MR,
+        MR: 'lua + Future<Output = Result<R>>;
 
     /// Add a regular method as a function which accepts generic arguments, the first argument will
-    /// be a `UserData` of type T if the method is called with Lua method syntax:
+    /// be a [`AnyUserData`] of type `T` if the method is called with Lua method syntax:
     /// `my_userdata:my_method(arg1, arg2)`, or it is passed in as the first argument:
     /// `my_userdata.my_method(my_userdata, arg1, arg2)`.
     ///
     /// Prefer to use [`add_method`] or [`add_method_mut`] as they are easier to use.
     ///
+    /// [`AnyUserData`]: struct.AnyUserData.html
     /// [`add_method`]: #method.add_method
     /// [`add_method_mut`]: #method.add_method_mut
     fn add_function<S, A, R, F>(&mut self, name: &S, function: F)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>;
+        F: 'static + MaybeSend + Fn(&'lua Lua, A) -> Result<R>;
 
     /// Add a regular method as a mutable function which accepts generic arguments.
     ///
@@ -171,10 +323,29 @@ pub trait UserDataMethods<'lua, T: UserData> {
     /// [`add_function`]: #method.add_function
     fn add_function_mut<S, A, R, F>(&mut self, name: &S, function: F)
     where
-        S: ?Sized + AsRef<[u8]>,
+        S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>;
+        F: 'static + MaybeSend + FnMut(&'lua Lua, A) -> Result<R>;
+
+    /// Add a regular method as an async function which accepts generic arguments
+    /// and returns Future.
+    ///
+    /// This is an async version of [`add_function`].
+    ///
+    /// Requires `feature = "async"`
+    ///
+    /// [`add_function`]: #method.add_function
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    fn add_async_function<S, A, R, F, FR>(&mut self, name: &S, function: F)
+    where
+        T: Clone,
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLuaMulti<'lua>,
+        R: ToLuaMulti<'lua>,
+        F: 'static + MaybeSend + Fn(&'lua Lua, A) -> FR,
+        FR: 'lua + Future<Output = Result<R>>;
 
     /// Add a metamethod which accepts a `&T` as the first parameter.
     ///
@@ -184,11 +355,12 @@ pub trait UserDataMethods<'lua, T: UserData> {
     /// side has a metatable. To prevent this, use [`add_meta_function`].
     ///
     /// [`add_meta_function`]: #method.add_meta_function
-    fn add_meta_method<A, R, M>(&mut self, meta: MetaMethod, method: M)
+    fn add_meta_method<S, A, R, M>(&mut self, meta: S, method: M)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + Fn(&'lua Lua, &T, A) -> Result<R>;
+        M: 'static + MaybeSend + Fn(&'lua Lua, &T, A) -> Result<R>;
 
     /// Add a metamethod as a function which accepts a `&mut T` as the first parameter.
     ///
@@ -198,33 +370,107 @@ pub trait UserDataMethods<'lua, T: UserData> {
     /// side has a metatable. To prevent this, use [`add_meta_function`].
     ///
     /// [`add_meta_function`]: #method.add_meta_function
-    fn add_meta_method_mut<A, R, M>(&mut self, meta: MetaMethod, method: M)
+    fn add_meta_method_mut<S, A, R, M>(&mut self, meta: S, method: M)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        M: 'static + Send + FnMut(&'lua Lua, &mut T, A) -> Result<R>;
+        M: 'static + MaybeSend + FnMut(&'lua Lua, &mut T, A) -> Result<R>;
 
     /// Add a metamethod which accepts generic arguments.
     ///
     /// Metamethods for binary operators can be triggered if either the left or right argument to
     /// the binary operator has a metatable, so the first argument here is not necessarily a
     /// userdata of type `T`.
-    fn add_meta_function<A, R, F>(&mut self, meta: MetaMethod, function: F)
+    fn add_meta_function<S, A, R, F>(&mut self, meta: S, function: F)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>;
+        F: 'static + MaybeSend + Fn(&'lua Lua, A) -> Result<R>;
 
     /// Add a metamethod as a mutable function which accepts generic arguments.
     ///
     /// This is a version of [`add_meta_function`] that accepts a FnMut argument.
     ///
     /// [`add_meta_function`]: #method.add_meta_function
-    fn add_meta_function_mut<A, R, F>(&mut self, meta: MetaMethod, function: F)
+    fn add_meta_function_mut<S, A, R, F>(&mut self, meta: S, function: F)
     where
+        S: Into<MetaMethod>,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
-        F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>;
+        F: 'static + MaybeSend + FnMut(&'lua Lua, A) -> Result<R>;
+}
+
+/// Field registry for [`UserData`] implementors.
+///
+/// [`UserData`]: trait.UserData.html
+pub trait UserDataFields<'lua, T: UserData> {
+    /// Add a regular field getter as a method which accepts a `&T` as the parameter.
+    ///
+    /// Regular field getters are implemented by overriding the `__index` metamethod and returning the
+    /// accessed field. This allows them to be used with the expected `userdata.field` syntax.
+    ///
+    /// If `add_meta_method` is used to set the `__index` metamethod, the `__index` metamethod will
+    /// be used as a fall-back if no regular field or method are found.
+    fn add_field_method_get<S, R, M>(&mut self, name: &S, method: M)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        R: ToLua<'lua>,
+        M: 'static + MaybeSend + Fn(&'lua Lua, &T) -> Result<R>;
+
+    /// Add a regular field setter as a method which accepts a `&mut T` as the first parameter.
+    ///
+    /// Regular field setters are implemented by overriding the `__newindex` metamethod and setting the
+    /// accessed field. This allows them to be used with the expected `userdata.field = value` syntax.
+    ///
+    /// If `add_meta_method` is used to set the `__newindex` metamethod, the `__newindex` metamethod will
+    /// be used as a fall-back if no regular field is found.
+    fn add_field_method_set<S, A, M>(&mut self, name: &S, method: M)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLua<'lua>,
+        M: 'static + MaybeSend + FnMut(&'lua Lua, &mut T, A) -> Result<()>;
+
+    /// Add a regular field getter as a function which accepts a generic [`AnyUserData`] of type `T`
+    /// argument.
+    ///
+    /// Prefer to use [`add_field_method_get`] as it is easier to use.
+    ///
+    /// [`AnyUserData`]: struct.AnyUserData.html
+    /// [`add_field_method_get`]: #method.add_field_method_get
+    fn add_field_function_get<S, R, F>(&mut self, name: &S, function: F)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        R: ToLua<'lua>,
+        F: 'static + MaybeSend + Fn(&'lua Lua, AnyUserData<'lua>) -> Result<R>;
+
+    /// Add a regular field setter as a function which accepts a generic [`AnyUserData`] of type `T`
+    /// first argument.
+    ///
+    /// Prefer to use [`add_field_method_set`] as it is easier to use.
+    ///
+    /// [`AnyUserData`]: struct.AnyUserData.html
+    /// [`add_field_method_set`]: #method.add_field_method_set
+    fn add_field_function_set<S, A, F>(&mut self, name: &S, function: F)
+    where
+        S: AsRef<[u8]> + ?Sized,
+        A: FromLua<'lua>,
+        F: 'static + MaybeSend + FnMut(&'lua Lua, AnyUserData<'lua>, A) -> Result<()>;
+
+    /// Add a metamethod value computed from `f`.
+    ///
+    /// This will initialize the metamethod value from `f` on `UserData` creation.
+    ///
+    /// # Note
+    ///
+    /// `mlua` will trigger an error on an attempt to define a protected metamethod,
+    /// like `__gc` or `__metatable`.
+    fn add_meta_field_with<S, R, F>(&mut self, meta: S, f: F)
+    where
+        S: Into<MetaMethod>,
+        F: 'static + MaybeSend + Fn(&'lua Lua) -> Result<R>,
+        R: ToLua<'lua>;
 }
 
 /// Trait for custom userdata types.
@@ -250,21 +496,21 @@ pub trait UserDataMethods<'lua, T: UserData> {
 /// # }
 /// ```
 ///
-/// Custom methods and operators can be provided by implementing `add_methods` (refer to
-/// [`UserDataMethods`] for more information):
+/// Custom fields, methods and operators can be provided by implementing `add_fields` or `add_methods`
+/// (refer to [`UserDataFields`] and [`UserDataMethods`] for more information):
 ///
 /// ```
-/// # use mlua::{Lua, MetaMethod, Result, UserData, UserDataMethods};
+/// # use mlua::{Lua, MetaMethod, Result, UserData, UserDataFields, UserDataMethods};
 /// # fn main() -> Result<()> {
 /// # let lua = Lua::new();
 /// struct MyUserData(i32);
 ///
 /// impl UserData for MyUserData {
-///     fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
-///         methods.add_method("get", |_, this, _: ()| {
-///             Ok(this.0)
-///         });
+///     fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+///         fields.add_field_method_get("val", |_, this| Ok(this.0));
+///     }
 ///
+///     fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
 ///         methods.add_method_mut("add", |_, this, value: i32| {
 ///             this.0 += value;
 ///             Ok(())
@@ -279,9 +525,9 @@ pub trait UserDataMethods<'lua, T: UserData> {
 /// lua.globals().set("myobject", MyUserData(123))?;
 ///
 /// lua.load(r#"
-///     assert(myobject:get() == 123)
+///     assert(myobject.val == 123)
 ///     myobject:add(7)
-///     assert(myobject:get() == 130)
+///     assert(myobject.val == 130)
 ///     assert(myobject + 10 == 140)
 /// "#).exec()?;
 /// # Ok(())
@@ -290,10 +536,113 @@ pub trait UserDataMethods<'lua, T: UserData> {
 ///
 /// [`ToLua`]: trait.ToLua.html
 /// [`FromLua`]: trait.FromLua.html
+/// [`UserDataFields`]: trait.UserDataFields.html
 /// [`UserDataMethods`]: trait.UserDataMethods.html
 pub trait UserData: Sized {
+    /// Adds custom fields specific to this userdata.
+    fn add_fields<'lua, F: UserDataFields<'lua, Self>>(_fields: &mut F) {}
+
     /// Adds custom methods and operators specific to this userdata.
-    fn add_methods<'lua, T: UserDataMethods<'lua, Self>>(_methods: &mut T) {}
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(_methods: &mut M) {}
+}
+
+// Wraps UserData in a way to always implement `serde::Serialize` trait.
+pub(crate) enum UserDataCell<T> {
+    Arc(Arc<RefCell<UserDataWrapped<T>>>),
+    Plain(RefCell<UserDataWrapped<T>>),
+}
+
+impl<T> UserDataCell<T> {
+    pub(crate) fn new(data: T) -> Self {
+        UserDataCell::Plain(RefCell::new(UserDataWrapped {
+            data: Box::into_raw(Box::new(data)),
+            #[cfg(feature = "serialize")]
+            ser: Box::into_raw(Box::new(UserDataSerializeError)),
+        }))
+    }
+
+    pub(crate) fn new_arc(data: T) -> Self {
+        UserDataCell::Arc(Arc::new(RefCell::new(UserDataWrapped {
+            data: Box::into_raw(Box::new(data)),
+            #[cfg(feature = "serialize")]
+            ser: Box::into_raw(Box::new(UserDataSerializeError)),
+        })))
+    }
+
+    #[cfg(feature = "serialize")]
+    pub(crate) fn new_ser(data: T) -> Self
+    where
+        T: 'static + Serialize,
+    {
+        let data_raw = Box::into_raw(Box::new(data));
+        UserDataCell::Plain(RefCell::new(UserDataWrapped {
+            data: data_raw,
+            ser: data_raw,
+        }))
+    }
+}
+
+impl<T> Deref for UserDataCell<T> {
+    type Target = RefCell<UserDataWrapped<T>>;
+
+    fn deref(&self) -> &Self::Target {
+        match self {
+            UserDataCell::Arc(t) => &*t,
+            UserDataCell::Plain(t) => &*t,
+        }
+    }
+}
+
+impl<T> Clone for UserDataCell<T> {
+    fn clone(&self) -> Self {
+        match self {
+            UserDataCell::Arc(t) => UserDataCell::Arc(t.clone()),
+            UserDataCell::Plain(_) => mlua_panic!("cannot clone non-arc userdata"),
+        }
+    }
+}
+
+pub(crate) struct UserDataWrapped<T> {
+    pub(crate) data: *mut T,
+    #[cfg(feature = "serialize")]
+    ser: *mut dyn erased_serde::Serialize,
+}
+
+impl<T> Drop for UserDataWrapped<T> {
+    fn drop(&mut self) {
+        unsafe {
+            drop(Box::from_raw(self.data));
+            #[cfg(feature = "serialize")]
+            if self.data as *mut () != self.ser as *mut () {
+                drop(Box::from_raw(self.ser));
+            }
+        }
+    }
+}
+
+impl<T> AsRef<T> for UserDataWrapped<T> {
+    fn as_ref(&self) -> &T {
+        unsafe { &*self.data }
+    }
+}
+
+impl<T> AsMut<T> for UserDataWrapped<T> {
+    fn as_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.data }
+    }
+}
+
+#[cfg(feature = "serialize")]
+pub(crate) struct UserDataSerializeError;
+
+#[cfg(feature = "serialize")]
+impl Serialize for UserDataSerializeError {
+    fn serialize<S>(&self, _serializer: S) -> StdResult<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        Err(ser::Error::custom("cannot serialize <userdata>"))
+    }
 }
 
 /// Handle to an internal Lua userdata for any type that implements [`UserData`].
@@ -318,7 +667,7 @@ pub struct AnyUserData<'lua>(pub(crate) LuaRef<'lua>);
 impl<'lua> AnyUserData<'lua> {
     /// Checks whether the type of this userdata is `T`.
     pub fn is<T: 'static + UserData>(&self) -> bool {
-        match self.inspect(|_: &RefCell<T>| Ok(())) {
+        match self.inspect(|_: &UserDataCell<T>| Ok(())) {
             Ok(()) => true,
             Err(Error::UserDataTypeMismatch) => false,
             Err(_) => unreachable!(),
@@ -332,7 +681,10 @@ impl<'lua> AnyUserData<'lua> {
     /// Returns a `UserDataBorrowError` if the userdata is already mutably borrowed. Returns a
     /// `UserDataTypeMismatch` if the userdata is not of type `T`.
     pub fn borrow<T: 'static + UserData>(&self) -> Result<Ref<T>> {
-        self.inspect(|cell| Ok(cell.try_borrow().map_err(|_| Error::UserDataBorrowError)?))
+        self.inspect(|cell| {
+            let cell_ref = cell.try_borrow().map_err(|_| Error::UserDataBorrowError)?;
+            Ok(Ref::map(cell_ref, |x| unsafe { &*x.data }))
+        })
     }
 
     /// Borrow this userdata mutably if it is of type `T`.
@@ -343,80 +695,124 @@ impl<'lua> AnyUserData<'lua> {
     /// `UserDataTypeMismatch` if the userdata is not of type `T`.
     pub fn borrow_mut<T: 'static + UserData>(&self) -> Result<RefMut<T>> {
         self.inspect(|cell| {
-            Ok(cell
+            let cell_ref = cell
                 .try_borrow_mut()
-                .map_err(|_| Error::UserDataBorrowMutError)?)
+                .map_err(|_| Error::UserDataBorrowMutError)?;
+            Ok(RefMut::map(cell_ref, |x| unsafe { &mut *x.data }))
         })
     }
 
     /// Sets an associated value to this `AnyUserData`.
     ///
     /// The value may be any Lua value whatsoever, and can be retrieved with [`get_user_value`].
+    /// As Lua < 5.3 allows to store only tables, the value will be stored in a table at index 1.
     ///
     /// [`get_user_value`]: #method.get_user_value
     pub fn set_user_value<V: ToLua<'lua>>(&self, v: V) -> Result<()> {
         let lua = self.0.lua;
         #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
         let v = {
-            // Lua 5.2/5.1 allows to store only table. Then we will wrap the value.
-            let t = lua.create_table()?;
+            // Lua <= 5.2 allows to store only a table. Then we will wrap the value.
+            let t = lua.create_table_with_capacity(1, 0)?;
             t.raw_set(1, v)?;
-            crate::Value::Table(t)
+            Value::Table(t)
         };
-        #[cfg(feature = "lua53")]
+        #[cfg(any(feature = "lua54", feature = "lua53"))]
         let v = v.to_lua(lua)?;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 2);
-            lua.push_ref(&self.0);
+            check_stack(lua.state, 3)?;
+
+            lua.push_userdata_ref(&self.0)?;
             lua.push_value(v)?;
             ffi::lua_setuservalue(lua.state, -2);
+
             Ok(())
         }
     }
 
     /// Returns an associated value set by [`set_user_value`].
     ///
+    /// For Lua < 5.3 the value will be automatically extracted from the table wrapper from index 1.
+    ///
     /// [`set_user_value`]: #method.set_user_value
     pub fn get_user_value<V: FromLua<'lua>>(&self) -> Result<V> {
         let lua = self.0.lua;
         let res = unsafe {
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 3);
-            lua.push_ref(&self.0);
+            check_stack(lua.state, 3)?;
+
+            lua.push_userdata_ref(&self.0)?;
             ffi::lua_getuservalue(lua.state, -1);
             lua.pop_value()
         };
         #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
-        return crate::Table::from_lua(res, lua)?.get(1);
-        #[cfg(feature = "lua53")]
+        return match <Option<Table>>::from_lua(res, lua)? {
+            Some(t) => t.get(1),
+            None => V::from_lua(Value::Nil, lua),
+        };
+        #[cfg(any(feature = "lua54", feature = "lua53"))]
         V::from_lua(res, lua)
     }
 
-    fn get_metatable(&self) -> Result<Table<'lua>> {
+    /// Returns a metatable of this `UserData`.
+    ///
+    /// Returned [`UserDataMetatable`] object wraps the original metatable and
+    /// provides safe access to it methods.
+    ///
+    /// For `T: UserData + 'static` returned metatable is shared among all instances of type `T`.
+    ///
+    /// [`UserDataMetatable`]: struct.UserDataMetatable.html
+    pub fn get_metatable(&self) -> Result<UserDataMetatable<'lua>> {
+        self.get_raw_metatable().map(UserDataMetatable)
+    }
+
+    /// Checks for a metamethod in this `AnyUserData`.
+    ///
+    /// This function is deprecated and will be removed in v0.7.
+    /// Please use [`get_metatable`] function instead.
+    ///
+    /// [`get_metatable`]: #method.get_metatable
+    #[deprecated(
+        since = "0.6.0",
+        note = "Please use the get_metatable function instead"
+    )]
+    pub fn has_metamethod(&self, method: MetaMethod) -> Result<bool> {
+        match self.get_raw_metatable() {
+            Ok(mt) => {
+                let name = self.0.lua.create_string(method.validate()?.name())?;
+                if let Value::Nil = mt.raw_get(name)? {
+                    Ok(false)
+                } else {
+                    Ok(true)
+                }
+            }
+            Err(Error::UserDataTypeMismatch) => Ok(false),
+            Err(e) => Err(e),
+        }
+    }
+
+    fn get_raw_metatable(&self) -> Result<Table<'lua>> {
         unsafe {
             let lua = self.0.lua;
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 3);
-
-            lua.push_ref(&self.0);
-
-            if ffi::lua_getmetatable(lua.state, -1) == 0 {
-                return Err(Error::UserDataTypeMismatch);
-            }
+            check_stack(lua.state, 3)?;
 
+            lua.push_userdata_ref(&self.0)?;
+            ffi::lua_getmetatable(lua.state, -1); // Checked that non-empty on the previous call
             Ok(Table(lua.pop_ref()))
         }
     }
 
     pub(crate) fn equals<T: AsRef<Self>>(&self, other: T) -> Result<bool> {
         let other = other.as_ref();
+        // Uses lua_rawequal() under the hood
         if self == other {
             return Ok(true);
         }
 
-        let mt = self.get_metatable()?;
-        if mt != other.get_metatable()? {
+        let mt = self.get_raw_metatable()?;
+        if mt != other.get_raw_metatable()? {
             return Ok(false);
         }
 
@@ -432,29 +828,30 @@ impl<'lua> AnyUserData<'lua> {
     fn inspect<'a, T, R, F>(&'a self, func: F) -> Result<R>
     where
         T: 'static + UserData,
-        F: FnOnce(&'a RefCell<T>) -> Result<R>,
+        F: FnOnce(&'a UserDataCell<T>) -> Result<R>,
     {
+        let lua = self.0.lua;
         unsafe {
-            let lua = self.0.lua;
             let _sg = StackGuard::new(lua.state);
-            assert_stack(lua.state, 3);
+            check_stack(lua.state, 3)?;
 
             lua.push_ref(&self.0);
-
             if ffi::lua_getmetatable(lua.state, -1) == 0 {
-                Err(Error::UserDataTypeMismatch)
-            } else {
-                ffi::lua_rawgeti(
-                    lua.state,
-                    ffi::LUA_REGISTRYINDEX,
-                    lua.userdata_metatable::<T>()? as ffi::lua_Integer,
-                );
+                return Err(Error::UserDataTypeMismatch);
+            }
+            lua.push_userdata_metatable::<T>()?;
 
-                if ffi::lua_rawequal(lua.state, -1, -2) == 0 {
-                    Err(Error::UserDataTypeMismatch)
+            if ffi::lua_rawequal(lua.state, -1, -2) == 0 {
+                // Maybe UserData destructed?
+                ffi::lua_pop(lua.state, 1);
+                get_destructed_userdata_metatable(lua.state);
+                if ffi::lua_rawequal(lua.state, -1, -2) == 1 {
+                    Err(Error::UserDataDestructed)
                 } else {
-                    func(&*get_userdata::<RefCell<T>>(lua.state, -3))
+                    Err(Error::UserDataTypeMismatch)
                 }
+            } else {
+                func(&*get_userdata::<UserDataCell<T>>(lua.state, -3))
             }
         }
     }
@@ -472,3 +869,98 @@ impl<'lua> AsRef<AnyUserData<'lua>> for AnyUserData<'lua> {
         self
     }
 }
+
+/// Handle to a `UserData` metatable.
+#[derive(Clone, Debug)]
+pub struct UserDataMetatable<'lua>(pub(crate) Table<'lua>);
+
+impl<'lua> UserDataMetatable<'lua> {
+    /// Gets the value associated to `key` from the metatable.
+    ///
+    /// If no value is associated to `key`, returns the `Nil` value.
+    /// Access to restricted metamethods such as `__gc` or `__metatable` will cause an error.
+    pub fn get<K: Into<MetaMethod>, V: FromLua<'lua>>(&self, key: K) -> Result<V> {
+        self.0.raw_get(key.into().validate()?.name())
+    }
+
+    /// Sets a key-value pair in the metatable.
+    ///
+    /// If the value is `Nil`, this will effectively remove the `key`.
+    /// Access to restricted metamethods such as `__gc` or `__metatable` will cause an error.
+    /// Setting `__index` or `__newindex` metamethods is also restricted because their values are cached
+    /// for `mlua` internal usage.
+    pub fn set<K: Into<MetaMethod>, V: ToLua<'lua>>(&self, key: K, value: V) -> Result<()> {
+        let key = key.into().validate()?;
+        // `__index` and `__newindex` cannot be changed in runtime, because values are cached
+        if key == MetaMethod::Index || key == MetaMethod::NewIndex {
+            return Err(Error::MetaMethodRestricted(key.to_string()));
+        }
+        self.0.raw_set(key.name(), value)
+    }
+
+    /// Checks whether the metatable contains a non-nil value for `key`.
+    pub fn contains<K: Into<MetaMethod>>(&self, key: K) -> Result<bool> {
+        self.0.contains_key(key.into().validate()?.name())
+    }
+
+    /// Consumes this metatable and returns an iterator over the pairs of the metatable.
+    ///
+    /// The pairs are wrapped in a [`Result`], since they are lazily converted to `V` type.
+    ///
+    /// [`Result`]: type.Result.html
+    pub fn pairs<V: FromLua<'lua>>(self) -> UserDataMetatablePairs<'lua, V> {
+        UserDataMetatablePairs(self.0.pairs())
+    }
+}
+
+/// An iterator over the pairs of a [`UserData`] metatable.
+///
+/// It skips restricted metamethods, such as `__gc` or `__metatable`.
+///
+/// This struct is created by the [`UserDataMetatable::pairs`] method.
+///
+/// [`UserData`]: trait.UserData.html
+/// [`UserDataMetatable::pairs`]: struct.UserDataMetatable.html#method.pairs
+pub struct UserDataMetatablePairs<'lua, V>(TablePairs<'lua, StdString, V>);
+
+impl<'lua, V> Iterator for UserDataMetatablePairs<'lua, V>
+where
+    V: FromLua<'lua>,
+{
+    type Item = Result<(MetaMethod, V)>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            match self.0.next()? {
+                Ok((key, value)) => {
+                    // Skip restricted metamethods
+                    if let Ok(metamethod) = MetaMethod::from(key).validate() {
+                        break Some(Ok((metamethod, value)));
+                    }
+                }
+                Err(e) => break Some(Err(e)),
+            }
+        }
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl<'lua> Serialize for AnyUserData<'lua> {
+    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let res = (|| unsafe {
+            let lua = self.0.lua;
+            let _sg = StackGuard::new(lua.state);
+            check_stack(lua.state, 3)?;
+
+            lua.push_userdata_ref(&self.0)?;
+            let ud = &*get_userdata::<UserDataCell<()>>(lua.state, -1);
+            (*ud.try_borrow().map_err(|_| Error::UserDataBorrowError)?.ser)
+                .serialize(serializer)
+                .map_err(|err| Error::SerializeError(err.to_string()))
+        })();
+        res.map_err(ser::Error::custom)
+    }
+}

src/value.rs

@@ -1,8 +1,13 @@
 use std::iter::{self, FromIterator};
 use std::{slice, str, vec};
 
+#[cfg(feature = "serialize")]
+use {
+    serde::ser::{self, Serialize, Serializer},
+    std::result::Result as StdResult,
+};
+
 use crate::error::{Error, Result};
-use crate::ffi;
 use crate::function::Function;
 use crate::lua::Lua;
 use crate::string::String;
@@ -11,10 +16,9 @@ use crate::thread::Thread;
 use crate::types::{Integer, LightUserData, Number};
 use crate::userdata::AnyUserData;
 
-/// A dynamically typed Lua value.  The `String`, `Table`, `Function`, `Thread`, and `UserData`
-/// variants contain handle types into the internal Lua state.  It is a logic error to mix handle
-/// types between separate `Lua` instances, or between a parent `Lua` instance and one received as a
-/// parameter in a Rust callback, and doing so will result in a panic.
+/// A dynamically typed Lua value. The `String`, `Table`, `Function`, `Thread`, and `UserData`
+/// variants contain handle types into the internal Lua state. It is a logic error to mix handle
+/// types between separate `Lua` instances, and doing so will result in a panic.
 #[derive(Debug, Clone)]
 pub enum Value<'lua> {
     /// The Lua value `nil`.
@@ -42,24 +46,25 @@ pub enum Value<'lua> {
     /// Reference to a userdata object that holds a custom type which implements `UserData`.
     /// Special builtin userdata types will be represented as other `Value` variants.
     UserData(AnyUserData<'lua>),
-    /// `Error` is a special builtin userdata type.  When received from Lua it is implicitly cloned.
+    /// `Error` is a special builtin userdata type. When received from Lua it is implicitly cloned.
     Error(Error),
 }
 pub use self::Value::Nil;
 
 impl<'lua> Value<'lua> {
-    pub(crate) fn type_name(&self) -> &'static str {
+    pub fn type_name(&self) -> &'static str {
         match *self {
             Value::Nil => "nil",
             Value::Boolean(_) => "boolean",
-            Value::LightUserData(_) => "light userdata",
+            Value::LightUserData(_) => "lightuserdata",
             Value::Integer(_) => "integer",
             Value::Number(_) => "number",
             Value::String(_) => "string",
             Value::Table(_) => "table",
             Value::Function(_) => "function",
             Value::Thread(_) => "thread",
-            Value::UserData(_) | Value::Error(_) => "userdata",
+            Value::UserData(_) => "userdata",
+            Value::Error(_) => "error",
         }
     }
 
@@ -89,8 +94,8 @@ impl<'lua> PartialEq for Value<'lua> {
             (Value::Boolean(a), Value::Boolean(b)) => a == b,
             (Value::LightUserData(a), Value::LightUserData(b)) => a == b,
             (Value::Integer(a), Value::Integer(b)) => *a == *b,
-            (Value::Integer(a), Value::Number(b)) => *a as ffi::lua_Number == *b,
-            (Value::Number(a), Value::Integer(b)) => *a == *b as ffi::lua_Number,
+            (Value::Integer(a), Value::Number(b)) => *a as Number == *b,
+            (Value::Number(a), Value::Integer(b)) => *a == *b as Number,
             (Value::Number(a), Value::Number(b)) => *a == *b,
             (Value::String(a), Value::String(b)) => a == b,
             (Value::Table(a), Value::Table(b)) => a == b,
@@ -109,6 +114,31 @@ impl<'lua> AsRef<Value<'lua>> for Value<'lua> {
     }
 }
 
+#[cfg(feature = "serialize")]
+impl<'lua> Serialize for Value<'lua> {
+    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        match self {
+            Value::Nil => serializer.serialize_unit(),
+            Value::Boolean(b) => serializer.serialize_bool(*b),
+            #[allow(clippy::useless_conversion)]
+            Value::Integer(i) => serializer.serialize_i64((*i).into()),
+            #[allow(clippy::useless_conversion)]
+            Value::Number(n) => serializer.serialize_f64((*n).into()),
+            Value::String(s) => s.serialize(serializer),
+            Value::Table(t) => t.serialize(serializer),
+            Value::UserData(ud) => ud.serialize(serializer),
+            Value::LightUserData(ud) if ud.0.is_null() => serializer.serialize_none(),
+            Value::Error(_) | Value::LightUserData(_) | Value::Function(_) | Value::Thread(_) => {
+                let msg = format!("cannot serialize <{}>", self.type_name());
+                Err(ser::Error::custom(msg))
+            }
+        }
+    }
+}
+
 /// Trait for types convertible to `Value`.
 pub trait ToLua<'lua> {
     /// Performs the conversion.
@@ -158,7 +188,7 @@ impl<'a, 'lua> IntoIterator for &'a MultiValue<'lua> {
     type IntoIter = iter::Rev<slice::Iter<'a, Value<'lua>>>;
 
     fn into_iter(self) -> Self::IntoIter {
-        (&self.0).into_iter().rev()
+        (&self.0).iter().rev()
     }
 }
 

tests/async.rs

@@ -0,0 +1,437 @@
+#![cfg(feature = "async")]
+
+use std::cell::Cell;
+use std::rc::Rc;
+use std::sync::{
+    atomic::{AtomicI64, Ordering},
+    Arc,
+};
+use std::time::Duration;
+
+use futures_timer::Delay;
+use futures_util::stream::TryStreamExt;
+
+use mlua::{
+    Error, Function, Lua, Result, Table, TableExt, Thread, UserData, UserDataMethods, Value,
+};
+
+#[tokio::test]
+async fn test_async_function() -> Result<()> {
+    let lua = Lua::new();
+
+    let f = lua
+        .create_async_function(|_lua, (a, b, c): (i64, i64, i64)| async move { Ok((a + b) * c) })?;
+    lua.globals().set("f", f)?;
+
+    let res: i64 = lua.load("f(1, 2, 3)").eval_async().await?;
+    assert_eq!(res, 9);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_sleep() -> Result<()> {
+    let lua = Lua::new();
+
+    let sleep = lua.create_async_function(move |_lua, n: u64| async move {
+        Delay::new(Duration::from_millis(n)).await;
+        Ok(format!("elapsed:{}ms", n))
+    })?;
+    lua.globals().set("sleep", sleep)?;
+
+    let res: String = lua.load(r"return sleep(...)").call_async(100).await?;
+    assert_eq!(res, "elapsed:100ms");
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_call() -> Result<()> {
+    let lua = Lua::new();
+
+    let hello = lua.create_async_function(|_lua, name: String| async move {
+        Delay::new(Duration::from_millis(10)).await;
+        Ok(format!("hello, {}!", name))
+    })?;
+
+    match hello.call::<_, ()>("alex") {
+        Err(Error::RuntimeError(_)) => {}
+        _ => panic!(
+            "non-async executing async function must fail on the yield stage with RuntimeError"
+        ),
+    };
+
+    assert_eq!(hello.call_async::<_, String>("alex").await?, "hello, alex!");
+
+    // Executing non-async functions using async call is allowed
+    let sum = lua.create_function(|_lua, (a, b): (i64, i64)| return Ok(a + b))?;
+    assert_eq!(sum.call_async::<_, i64>((5, 1)).await?, 6);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_bind_call() -> Result<()> {
+    let lua = Lua::new();
+
+    let sum = lua.create_async_function(|_lua, (a, b): (i64, i64)| async move { Ok(a + b) })?;
+
+    let plus_10 = sum.bind(10)?;
+    lua.globals().set("plus_10", plus_10)?;
+
+    assert_eq!(lua.load("plus_10(-1)").eval_async::<i64>().await?, 9);
+    assert_eq!(lua.load("plus_10(1)").eval_async::<i64>().await?, 11);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_handle_yield() -> Result<()> {
+    let lua = Lua::new();
+
+    let sum = lua.create_async_function(|_lua, (a, b): (i64, i64)| async move {
+        Delay::new(Duration::from_millis(10)).await;
+        Ok(a + b)
+    })?;
+
+    lua.globals().set("sleep_sum", sum)?;
+
+    let res: String = lua
+        .load(
+            r#"
+        sum = sleep_sum(6, 7)
+        assert(sum == 13)
+        coroutine.yield("in progress")
+        return "done"
+    "#,
+        )
+        .call_async(())
+        .await?;
+
+    assert_eq!(res, "done");
+
+    let min = lua
+        .load(
+            r#"
+        function (a, b)
+            coroutine.yield("ignore me")
+            if a < b then return a else return b end
+        end
+    "#,
+        )
+        .eval::<Function>()?;
+    assert_eq!(min.call_async::<_, i64>((-1, 1)).await?, -1);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_multi_return_nil() -> Result<()> {
+    let lua = Lua::new();
+    lua.globals().set(
+        "func",
+        lua.create_async_function(|_, _: ()| async { Ok((Option::<String>::None, "error")) })?,
+    )?;
+
+    lua.load(
+        r#"
+        local ok, err = func()
+        assert(err == "error")
+    "#,
+    )
+    .exec_async()
+    .await
+}
+
+#[tokio::test]
+async fn test_async_return_async_closure() -> Result<()> {
+    let lua = Lua::new();
+
+    let f = lua.create_async_function(|lua, a: i64| async move {
+        Delay::new(Duration::from_millis(10)).await;
+
+        let g = lua.create_async_function(move |_, b: i64| async move {
+            Delay::new(Duration::from_millis(10)).await;
+            return Ok(a + b);
+        })?;
+
+        Ok(g)
+    })?;
+
+    lua.globals().set("f", f)?;
+
+    let res: i64 = lua
+        .load("local g = f(1); return g(2) + g(3)")
+        .call_async(())
+        .await?;
+
+    assert_eq!(res, 7);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_thread_stream() -> Result<()> {
+    let lua = Lua::new();
+
+    let thread = lua.create_thread(
+        lua.load(
+            r#"
+            function (sum)
+                for i = 1,10 do
+                    sum = sum + i
+                    coroutine.yield(sum)
+                end
+                return sum
+            end
+            "#,
+        )
+        .eval()?,
+    )?;
+
+    let mut stream = thread.into_async::<_, i64>(1);
+    let mut sum = 0;
+    while let Some(n) = stream.try_next().await? {
+        sum += n;
+    }
+
+    assert_eq!(sum, 286);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_thread() -> Result<()> {
+    let lua = Lua::new();
+
+    let cnt = Arc::new(10); // sleep 10ms
+    let cnt2 = cnt.clone();
+    let f = lua.create_async_function(move |_lua, ()| {
+        let cnt3 = cnt2.clone();
+        async move {
+            Delay::new(Duration::from_millis(*cnt3.as_ref())).await;
+            Ok("done")
+        }
+    })?;
+
+    let res: String = lua.create_thread(f)?.into_async(()).await?;
+
+    assert_eq!(res, "done");
+
+    assert_eq!(Arc::strong_count(&cnt), 2);
+    lua.gc_collect()?; // thread_s is non-resumable and subject to garbage collection
+    assert_eq!(Arc::strong_count(&cnt), 1);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_table() -> Result<()> {
+    let lua = Lua::new();
+
+    let table = lua.create_table()?;
+    table.set("val", 10)?;
+
+    let get_value = lua.create_async_function(|_, table: Table| async move {
+        Delay::new(Duration::from_millis(10)).await;
+        table.get::<_, i64>("val")
+    })?;
+    table.set("get_value", get_value)?;
+
+    let set_value = lua.create_async_function(|_, (table, n): (Table, i64)| async move {
+        Delay::new(Duration::from_millis(10)).await;
+        table.set("val", n)
+    })?;
+    table.set("set_value", set_value)?;
+
+    let sleep = lua.create_async_function(|_, n| async move {
+        Delay::new(Duration::from_millis(n)).await;
+        Ok(format!("elapsed:{}ms", n))
+    })?;
+    table.set("sleep", sleep)?;
+
+    assert_eq!(
+        table
+            .call_async_method::<_, _, i64>("get_value", ())
+            .await?,
+        10
+    );
+    table.call_async_method("set_value", 15).await?;
+    assert_eq!(
+        table
+            .call_async_method::<_, _, i64>("get_value", ())
+            .await?,
+        15
+    );
+    assert_eq!(
+        table
+            .call_async_function::<_, _, String>("sleep", 7)
+            .await?,
+        "elapsed:7ms"
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_userdata() -> Result<()> {
+    #[derive(Clone)]
+    struct MyUserData(Arc<AtomicI64>);
+
+    impl UserData for MyUserData {
+        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_async_method("get_value", |_, data, ()| async move {
+                Delay::new(Duration::from_millis(10)).await;
+                Ok(data.0.load(Ordering::Relaxed))
+            });
+
+            methods.add_async_method("set_value", |_, data, n| async move {
+                Delay::new(Duration::from_millis(10)).await;
+                data.0.store(n, Ordering::Relaxed);
+                Ok(())
+            });
+
+            methods.add_async_function("sleep", |_, n| async move {
+                Delay::new(Duration::from_millis(n)).await;
+                Ok(format!("elapsed:{}ms", n))
+            });
+        }
+    }
+
+    let lua = Lua::new();
+    let globals = lua.globals();
+
+    let userdata = lua.create_userdata(MyUserData(Arc::new(AtomicI64::new(11))))?;
+    globals.set("userdata", userdata.clone())?;
+
+    lua.load(
+        r#"
+        assert(userdata:get_value() == 11)
+        userdata:set_value(12)
+        assert(userdata.sleep(5) == "elapsed:5ms")
+        assert(userdata:get_value() == 12)
+    "#,
+    )
+    .exec_async()
+    .await?;
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_scope() -> Result<()> {
+    let ref lua = Lua::new();
+
+    let ref rc = Rc::new(Cell::new(0));
+
+    let fut = lua.async_scope(|scope| async move {
+        let f = scope.create_async_function(move |_, n: u64| {
+            let rc2 = rc.clone();
+            async move {
+                rc2.set(42);
+                Delay::new(Duration::from_millis(n)).await;
+                assert_eq!(Rc::strong_count(&rc2), 2);
+                Ok(())
+            }
+        })?;
+
+        lua.globals().set("f", f.clone())?;
+
+        assert_eq!(Rc::strong_count(rc), 1);
+        let _ = f.call_async::<u64, ()>(10).await?;
+        assert_eq!(Rc::strong_count(rc), 1);
+
+        // Create future in partialy polled state (Poll::Pending)
+        let g = lua.create_thread(f)?;
+        g.resume::<u64, ()>(10)?;
+        lua.globals().set("g", g)?;
+        assert_eq!(Rc::strong_count(rc), 2);
+
+        Ok(())
+    });
+
+    assert_eq!(Rc::strong_count(rc), 1);
+    let _ = fut.await?;
+    assert_eq!(Rc::strong_count(rc), 1);
+
+    match lua
+        .globals()
+        .get::<_, Function>("f")?
+        .call_async::<_, ()>(10)
+        .await
+    {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::CallbackDestructed => {}
+            e => panic!("expected `CallbackDestructed` error cause, got {:?}", e),
+        },
+        r => panic!("improper return for destructed function: {:?}", r),
+    };
+
+    match lua.globals().get::<_, Thread>("g")?.resume::<_, Value>(()) {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::CallbackDestructed => {}
+            e => panic!("expected `CallbackDestructed` error cause, got {:?}", e),
+        },
+        r => panic!("improper return for destructed function: {:?}", r),
+    };
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_async_scope_userdata() -> Result<()> {
+    #[derive(Clone)]
+    struct MyUserData(Arc<AtomicI64>);
+
+    impl UserData for MyUserData {
+        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_async_method("get_value", |_, data, ()| async move {
+                Delay::new(Duration::from_millis(10)).await;
+                Ok(data.0.load(Ordering::Relaxed))
+            });
+
+            methods.add_async_method("set_value", |_, data, n| async move {
+                Delay::new(Duration::from_millis(10)).await;
+                data.0.store(n, Ordering::Relaxed);
+                Ok(())
+            });
+
+            methods.add_async_function("sleep", |_, n| async move {
+                Delay::new(Duration::from_millis(n)).await;
+                Ok(format!("elapsed:{}ms", n))
+            });
+        }
+    }
+
+    let ref lua = Lua::new();
+
+    let ref arc = Arc::new(AtomicI64::new(11));
+
+    lua.async_scope(|scope| async move {
+        let ud = scope.create_userdata(MyUserData(arc.clone()))?;
+        lua.globals().set("userdata", ud)?;
+        lua.load(
+            r#"
+            assert(userdata:get_value() == 11)
+            userdata:set_value(12)
+            assert(userdata.sleep(5) == "elapsed:5ms")
+            assert(userdata:get_value() == 12)
+        "#,
+        )
+        .exec_async()
+        .await
+    })
+    .await?;
+
+    assert_eq!(Arc::strong_count(arc), 1);
+
+    match lua.load("userdata:get_value()").exec_async().await {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::CallbackDestructed => {}
+            e => panic!("expected `CallbackDestructed` error cause, got {:?}", e),
+        },
+        r => panic!("improper return for destructed userdata: {:?}", r),
+    };
+
+    Ok(())
+}

tests/compile.rs

@@ -0,0 +1,24 @@
+#[test]
+#[ignore]
+fn test_compilation() {
+    let t = trybuild::TestCases::new();
+
+    t.compile_fail("tests/compile/function_borrow.rs");
+    t.compile_fail("tests/compile/lua_norefunwindsafe.rs");
+    t.compile_fail("tests/compile/ref_nounwindsafe.rs");
+    t.compile_fail("tests/compile/scope_callback_capture.rs");
+    t.compile_fail("tests/compile/scope_callback_inner.rs");
+    t.compile_fail("tests/compile/scope_callback_outer.rs");
+    t.compile_fail("tests/compile/scope_invariance.rs");
+    t.compile_fail("tests/compile/scope_mutable_aliasing.rs");
+    t.compile_fail("tests/compile/scope_userdata_borrow.rs");
+    t.compile_fail("tests/compile/static_callback_args.rs");
+
+    #[cfg(feature = "async")]
+    t.compile_fail("tests/compile/async_nonstatic_userdata.rs");
+
+    #[cfg(feature = "send")]
+    t.compile_fail("tests/compile/non_send.rs");
+    #[cfg(not(feature = "send"))]
+    t.pass("tests/compile/non_send.rs");
+}

tests/compile/async_nonstatic_userdata.rs

@@ -0,0 +1,17 @@
+use mlua::{Lua, UserData, UserDataMethods};
+
+fn main() {
+    let ref lua = Lua::new();
+
+    #[derive(Clone)]
+    struct MyUserData<'a>(&'a i64);
+
+    impl<'a> UserData for MyUserData<'a> {
+        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_async_method("print", |_, data, ()| async move {
+                println!("{}", data.0);
+                Ok(())
+            });
+        }
+    }
+}

tests/compile/async_nonstatic_userdata.stderr

@@ -0,0 +1,36 @@
+error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
+  --> $DIR/async_nonstatic_userdata.rs:11:72
+   |
+11 |               methods.add_async_method("print", |_, data, ()| async move {
+   |  ________________________________________________________________________^
+12 | |                 println!("{}", data.0);
+13 | |                 Ok(())
+14 | |             });
+   | |_____________^
+   |
+note: first, the lifetime cannot outlive the lifetime `'a` as defined on the impl at 9:10...
+  --> $DIR/async_nonstatic_userdata.rs:9:10
+   |
+9  |     impl<'a> UserData for MyUserData<'a> {
+   |          ^^
+note: ...so that the types are compatible
+  --> $DIR/async_nonstatic_userdata.rs:11:72
+   |
+11 |               methods.add_async_method("print", |_, data, ()| async move {
+   |  ________________________________________________________________________^
+12 | |                 println!("{}", data.0);
+13 | |                 Ok(())
+14 | |             });
+   | |_____________^
+   = note: expected `(MyUserData<'_>,)`
+              found `(MyUserData<'a>,)`
+note: but, the lifetime must be valid for the lifetime `'lua` as defined on the method body at 10:24...
+  --> $DIR/async_nonstatic_userdata.rs:10:24
+   |
+10 |         fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+   |                        ^^^^
+note: ...so that the type `impl Future` will meet its required lifetime bounds
+  --> $DIR/async_nonstatic_userdata.rs:11:21
+   |
+11 |             methods.add_async_method("print", |_, data, ()| async move {
+   |                     ^^^^^^^^^^^^^^^^

tests/compile/lua_norefunwindsafe.stderr

@@ -0,0 +1,16 @@
+error[E0277]: the type `UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+   --> $DIR/lua_norefunwindsafe.rs:7:5
+    |
+7   |     catch_unwind(|| lua.create_table().unwrap());
+    |     ^^^^^^^^^^^^ `UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+    |
+   ::: $RUST/std/src/panic.rs
+    |
+    | pub fn catch_unwind<F: FnOnce() -> R + UnwindSafe, R>(f: F) -> Result<R> {
+    |                                        ---------- required by this bound in `catch_unwind`
+    |
+    = help: within `Lua`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<()>`
+    = note: required because it appears within the type `PhantomData<UnsafeCell<()>>`
+    = note: required because it appears within the type `Lua`
+    = note: required because of the requirements on the impl of `UnwindSafe` for `&Lua`
+    = note: required because it appears within the type `[closure@$DIR/tests/compile/lua_norefunwindsafe.rs:7:18: 7:48]`

tests/compile/non_send.rs

@@ -0,0 +1,17 @@
+use std::cell::Cell;
+use std::rc::Rc;
+
+use mlua::{Lua, Result};
+
+fn main() -> Result<()> {
+    let lua = Lua::new();
+
+    let data = Rc::new(Cell::new(0));
+
+    lua.create_function(move |_, ()| {
+        Ok(data.get())
+    })?
+    .call::<_, i32>(())?;
+
+    Ok(())
+}

tests/compile/non_send.stderr

@@ -0,0 +1,14 @@
+error[E0277]: `Rc<Cell<i32>>` cannot be sent between threads safely
+  --> $DIR/non_send.rs:11:9
+   |
+11 |       lua.create_function(move |_, ()| {
+   |  _________^^^^^^^^^^^^^^^_-
+   | |         |
+   | |         `Rc<Cell<i32>>` cannot be sent between threads safely
+12 | |         Ok(data.get())
+13 | |     })?
+   | |_____- within this `[closure@$DIR/tests/compile/non_send.rs:11:25: 13:6]`
+   |
+   = help: within `[closure@$DIR/tests/compile/non_send.rs:11:25: 13:6]`, the trait `Send` is not implemented for `Rc<Cell<i32>>`
+   = note: required because it appears within the type `[closure@$DIR/tests/compile/non_send.rs:11:25: 13:6]`
+   = note: required because of the requirements on the impl of `mlua::types::MaybeSend` for `[closure@$DIR/tests/compile/non_send.rs:11:25: 13:6]`

tests/compile/ref_nounwindsafe.stderr

@@ -0,0 +1,18 @@
+error[E0277]: the type `UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+   --> $DIR/ref_nounwindsafe.rs:8:5
+    |
+8   |     catch_unwind(move || table.set("a", "b").unwrap());
+    |     ^^^^^^^^^^^^ `UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+    |
+   ::: $RUST/std/src/panic.rs
+    |
+    | pub fn catch_unwind<F: FnOnce() -> R + UnwindSafe, R>(f: F) -> Result<R> {
+    |                                        ---------- required by this bound in `catch_unwind`
+    |
+    = help: within `Lua`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<()>`
+    = note: required because it appears within the type `PhantomData<UnsafeCell<()>>`
+    = note: required because it appears within the type `Lua`
+    = note: required because of the requirements on the impl of `UnwindSafe` for `&Lua`
+    = note: required because it appears within the type `mlua::types::LuaRef<'_>`
+    = note: required because it appears within the type `LuaTable<'_>`
+    = note: required because it appears within the type `[closure@$DIR/tests/compile/ref_nounwindsafe.rs:8:18: 8:54]`

tests/compile/scope_callback_capture.rs

@@ -1,15 +1,11 @@
-use mlua::{Lua, Table, Result};
-
-struct Test {
-    field: i32,
-}
+use mlua::{Lua, Table};
 
 fn main() {
     let lua = Lua::new();
-    lua.scope(|scope| -> Result<()> {
+    lua.scope(|scope| {
         let mut inner: Option<Table> = None;
         let f = scope
-            .create_function_mut(move |lua, t: Table| {
+            .create_function_mut(move |_, t: Table| {
                 if let Some(old) = inner.take() {
                     // Access old callback `Lua`.
                 }

tests/compile/scope_callback_capture.stderr

@@ -0,0 +1,26 @@
+warning: unused variable: `old`
+ --> $DIR/scope_callback_capture.rs:9:29
+  |
+9 |                 if let Some(old) = inner.take() {
+  |                             ^^^ help: if this is intentional, prefix it with an underscore: `_old`
+  |
+  = note: `#[warn(unused_variables)]` on by default
+
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/scope_callback_capture.rs:7:17
+   |
+5  |       lua.scope(|scope| {
+   |                  -----
+   |                  |
+   |                  `scope` declared here, outside of the closure body
+   |                  `scope` is a reference that is only valid in the closure body
+6  |           let mut inner: Option<Table> = None;
+7  |           let f = scope
+   |  _________________^
+8  | |             .create_function_mut(move |_, t: Table| {
+9  | |                 if let Some(old) = inner.take() {
+10 | |                     // Access old callback `Lua`.
+...  |
+13 | |                 Ok(())
+14 | |             })?;
+   | |______________^ `scope` escapes the closure body here

tests/compile/scope_callback_inner.rs

@@ -1,12 +1,8 @@
-use mlua::{Lua, Table, Result};
-
-struct Test {
-    field: i32,
-}
+use mlua::{Lua, Table};
 
 fn main() {
     let lua = Lua::new();
-    lua.scope(|scope| -> Result<()> {
+    lua.scope(|scope| {
         let mut inner: Option<Table> = None;
         let f = scope
             .create_function_mut(|_, t: Table| {

tests/compile/scope_callback_inner.stderr

@@ -0,0 +1,42 @@
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/scope_callback_inner.rs:7:17
+   |
+5  |       lua.scope(|scope| {
+   |                  -----
+   |                  |
+   |                  `scope` declared here, outside of the closure body
+   |                  `scope` is a reference that is only valid in the closure body
+6  |           let mut inner: Option<Table> = None;
+7  |           let f = scope
+   |  _________________^
+8  | |             .create_function_mut(|_, t: Table| {
+9  | |                 inner = Some(t);
+10 | |                 Ok(())
+11 | |             })?;
+   | |______________^ `scope` escapes the closure body here
+
+error[E0373]: closure may outlive the current function, but it borrows `inner`, which is owned by the current function
+  --> $DIR/scope_callback_inner.rs:8:34
+   |
+5  |     lua.scope(|scope| {
+   |                ----- has type `&Scope<'_, '2>`
+...
+8  |             .create_function_mut(|_, t: Table| {
+   |                                  ^^^^^^^^^^^^^ may outlive borrowed value `inner`
+9  |                 inner = Some(t);
+   |                 ----- `inner` is borrowed here
+   |
+note: function requires argument type to outlive `'2`
+  --> $DIR/scope_callback_inner.rs:7:17
+   |
+7  |           let f = scope
+   |  _________________^
+8  | |             .create_function_mut(|_, t: Table| {
+9  | |                 inner = Some(t);
+10 | |                 Ok(())
+11 | |             })?;
+   | |______________^
+help: to force the closure to take ownership of `inner` (and any other referenced variables), use the `move` keyword
+   |
+8  |             .create_function_mut(move |_, t: Table| {
+   |                                  ^^^^^^^^^^^^^^^^^^

tests/compile/scope_callback_outer.rs

@@ -1,13 +1,9 @@
-use mlua::{Lua, Table, Result};
-
-struct Test {
-    field: i32,
-}
+use mlua::{Lua, Table};
 
 fn main() {
     let lua = Lua::new();
     let mut outer: Option<Table> = None;
-    lua.scope(|scope| -> Result<()> {
+    lua.scope(|scope| {
         let f = scope
             .create_function_mut(|_, t: Table| {
                 outer = Some(t);

tests/compile/scope_callback_outer.stderr

@@ -0,0 +1,30 @@
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/scope_callback_outer.rs:7:17
+   |
+6  |       lua.scope(|scope| {
+   |                  -----
+   |                  |
+   |                  `scope` declared here, outside of the closure body
+   |                  `scope` is a reference that is only valid in the closure body
+7  |           let f = scope
+   |  _________________^
+8  | |             .create_function_mut(|_, t: Table| {
+9  | |                 outer = Some(t);
+10 | |                 Ok(())
+11 | |             })?;
+   | |______________^ `scope` escapes the closure body here
+
+error[E0597]: `outer` does not live long enough
+  --> $DIR/scope_callback_outer.rs:9:17
+   |
+6  |     lua.scope(|scope| {
+   |               ------- value captured here
+...
+9  |                 outer = Some(t);
+   |                 ^^^^^ borrowed value does not live long enough
+...
+15 | }
+   | -
+   | |
+   | `outer` dropped here while still borrowed
+   | borrow might be used here, when `outer` is dropped and runs the destructor for type `Option<LuaTable<'_>>`

tests/compile/scope_invariance.rs

@@ -1,4 +1,4 @@
-use mlua::{Lua, Result};
+use mlua::Lua;
 
 struct Test {
     field: i32,
@@ -6,7 +6,7 @@ struct Test {
 
 fn main() {
     let lua = Lua::new();
-    lua.scope(|scope| -> Result<()> {
+    lua.scope(|scope| {
         let f = {
             let mut test = Test { field: 0 };
 

tests/compile/scope_invariance.stderr

@@ -1,8 +1,8 @@
 error[E0373]: closure may outlive the current function, but it borrows `test`, which is owned by the current function
   --> $DIR/scope_invariance.rs:14:38
    |
-9  |     lua.scope(|scope| -> Result<()> {
-   |                ----- has type `&mlua::scope::Scope<'_, '1>`
+9  |     lua.scope(|scope| {
+   |                ----- has type `&Scope<'_, '1>`
 ...
 14 |                 .create_function_mut(|_, ()| {
    |                                      ^^^^^^^ may outlive borrowed value `test`

tests/compile/scope_mutable_aliasing.rs

@@ -1,15 +1,15 @@
-use mlua::{Lua, UserData, Result};
-
-struct MyUserData<'a>(&'a mut i32);
-impl<'a> UserData for MyUserData<'a> {}
+use mlua::{Lua, UserData};
 
 fn main() {
+    struct MyUserData<'a>(&'a mut i32);
+    impl<'a> UserData for MyUserData<'a> {};
+
     let mut i = 1;
 
     let lua = Lua::new();
-    lua.scope(|scope| -> Result<()> {
-        let _a = scope.create_nonstatic_userdata(MyUserData(&mut i))?;
-        let _b = scope.create_nonstatic_userdata(MyUserData(&mut i))?;
+    lua.scope(|scope| {
+        let _a = scope.create_nonstatic_userdata(MyUserData(&mut i)).unwrap();
+        let _b = scope.create_nonstatic_userdata(MyUserData(&mut i)).unwrap();
         Ok(())
     });
 }

tests/compile/scope_mutable_aliasing.stderr

@@ -1,9 +1,9 @@
 error[E0499]: cannot borrow `i` as mutable more than once at a time
   --> $DIR/scope_mutable_aliasing.rs:12:61
    |
-11 |         let _a = scope.create_nonstatic_userdata(MyUserData(&mut i))?;
+11 |         let _a = scope.create_nonstatic_userdata(MyUserData(&mut i)).unwrap();
    |                                                             ------ first mutable borrow occurs here
-12 |         let _b = scope.create_nonstatic_userdata(MyUserData(&mut i))?;
+12 |         let _b = scope.create_nonstatic_userdata(MyUserData(&mut i)).unwrap();
    |                        -------------------------            ^^^^^^ second mutable borrow occurs here
    |                        |
    |                        first borrow later used by call

tests/compile/scope_userdata_borrow.rs

@@ -1,19 +1,18 @@
-use mlua::{Lua, UserData, Result};
-
-struct MyUserData<'a>(&'a i32);
-impl<'a> UserData for MyUserData<'a> {}
+use mlua::{Lua, UserData};
 
 fn main() {
     // Should not allow userdata borrow to outlive lifetime of AnyUserData handle
+    struct MyUserData<'a>(&'a i32);
+    impl<'a> UserData for MyUserData<'a> {};
 
     let igood = 1;
 
     let lua = Lua::new();
-    lua.scope(|scope| -> Result<()> {
-        let _ugood = scope.create_nonstatic_userdata(MyUserData(&igood))?;
+    lua.scope(|scope| {
+        let _ugood = scope.create_nonstatic_userdata(MyUserData(&igood)).unwrap();
         let _ubad = {
             let ibad = 42;
-            scope.create_nonstatic_userdata(MyUserData(&ibad))?;
+            scope.create_nonstatic_userdata(MyUserData(&ibad)).unwrap();
         };
         Ok(())
     });

tests/compile/scope_userdata_borrow.stderr

@@ -1,13 +1,13 @@
 error[E0597]: `ibad` does not live long enough
-  --> $DIR/scope_userdata_borrow.rs:16:56
+  --> $DIR/scope_userdata_borrow.rs:15:56
    |
-12 |     lua.scope(|scope| -> Result<()> {
-   |                ----- has type `&mlua::scope::Scope<'_, '1>`
+11 |     lua.scope(|scope| {
+   |                ----- has type `&Scope<'_, '1>`
 ...
-16 |             scope.create_nonstatic_userdata(MyUserData(&ibad))?;
+15 |             scope.create_nonstatic_userdata(MyUserData(&ibad)).unwrap();
    |             -------------------------------------------^^^^^--
    |             |                                          |
    |             |                                          borrowed value does not live long enough
    |             argument requires that `ibad` is borrowed for `'1`
-17 |         };
+16 |         };
    |         - `ibad` dropped here while still borrowed

tests/compile/static_callback_args.rs

@@ -0,0 +1,32 @@
+use std::cell::RefCell;
+
+use mlua::{Lua, Result, Table};
+
+fn main() -> Result<()> {
+    thread_local! {
+        static BAD_TIME: RefCell<Option<Table<'static>>> = RefCell::new(None);
+    }
+
+    let lua = Lua::new();
+
+    lua.create_function(|_, table: Table| {
+        BAD_TIME.with(|bt| {
+            *bt.borrow_mut() = Some(table);
+        });
+        Ok(())
+    })?
+    .call::<_, ()>(lua.create_table()?)?;
+
+    // In debug, this will panic with a reference leak before getting to the next part but
+    // it segfaults anyway.
+    drop(lua);
+
+    BAD_TIME.with(|bt| {
+        println!(
+            "you're gonna have a bad time: {}",
+            bt.borrow().as_ref().unwrap().len().unwrap()
+        );
+    });
+
+    Ok(())
+}

tests/compile/static_callback_args.stderr

@@ -0,0 +1,35 @@
+error[E0597]: `lua` does not live long enough
+  --> $DIR/static_callback_args.rs:12:5
+   |
+12 |       lua.create_function(|_, table: Table| {
+   |       -^^
+   |       |
+   |  _____borrowed value does not live long enough
+   | |
+13 | |         BAD_TIME.with(|bt| {
+14 | |             *bt.borrow_mut() = Some(table);
+15 | |         });
+16 | |         Ok(())
+17 | |     })?
+   | |______- argument requires that `lua` is borrowed for `'static`
+...
+32 |   }
+   |   - `lua` dropped here while still borrowed
+
+error[E0505]: cannot move out of `lua` because it is borrowed
+  --> $DIR/static_callback_args.rs:22:10
+   |
+12 |       lua.create_function(|_, table: Table| {
+   |       ---
+   |       |
+   |  _____borrow of `lua` occurs here
+   | |
+13 | |         BAD_TIME.with(|bt| {
+14 | |             *bt.borrow_mut() = Some(table);
+15 | |         });
+16 | |         Ok(())
+17 | |     })?
+   | |______- argument requires that `lua` is borrowed for `'static`
+...
+22 |       drop(lua);
+   |            ^^^ move out of `lua` occurs here

tests/compile_fail.rs

@@ -1,6 +0,0 @@
-#[test]
-#[ignore]
-fn test_compile_fail() {
-    let t = trybuild::TestCases::new();
-    t.compile_fail("tests/compile_fail/*.rs");
-}

tests/compile_fail/lua_norefunwindsafe.stderr

@@ -1,42 +0,0 @@
-error[E0277]: the type `std::cell::UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-   --> $DIR/lua_norefunwindsafe.rs:7:5
-    |
-7   |     catch_unwind(|| lua.create_table().unwrap());
-    |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-    |
-    = help: within `mlua::lua::Lua`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<()>`
-    = note: required because it appears within the type `std::marker::PhantomData<std::cell::UnsafeCell<()>>`
-    = note: required because it appears within the type `mlua::lua::Lua`
-    = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&mlua::lua::Lua`
-    = note: required because it appears within the type `[closure@$DIR/tests/compile_fail/lua_norefunwindsafe.rs:7:18: 7:48 lua:&mlua::lua::Lua]`
-
-error[E0277]: the type `std::cell::UnsafeCell<mlua::lua::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-   --> $DIR/lua_norefunwindsafe.rs:7:5
-    |
-7   |     catch_unwind(|| lua.create_table().unwrap());
-    |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<mlua::lua::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-    |
-    = help: within `mlua::lua::Lua`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<mlua::lua::ExtraData>`
-    = note: required because it appears within the type `std::cell::RefCell<mlua::lua::ExtraData>`
-    = note: required because it appears within the type `alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `std::marker::PhantomData<alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>>`
-    = note: required because it appears within the type `std::sync::Arc<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `mlua::lua::Lua`
-    = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&mlua::lua::Lua`
-    = note: required because it appears within the type `[closure@$DIR/tests/compile_fail/lua_norefunwindsafe.rs:7:18: 7:48 lua:&mlua::lua::Lua]`
-
-error[E0277]: the type `std::cell::UnsafeCell<isize>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-   --> $DIR/lua_norefunwindsafe.rs:7:5
-    |
-7   |     catch_unwind(|| lua.create_table().unwrap());
-    |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<isize>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-    |
-    = help: within `mlua::lua::Lua`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<isize>`
-    = note: required because it appears within the type `std::cell::Cell<isize>`
-    = note: required because it appears within the type `std::cell::RefCell<mlua::lua::ExtraData>`
-    = note: required because it appears within the type `alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `std::marker::PhantomData<alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>>`
-    = note: required because it appears within the type `std::sync::Arc<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `mlua::lua::Lua`
-    = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&mlua::lua::Lua`
-    = note: required because it appears within the type `[closure@$DIR/tests/compile_fail/lua_norefunwindsafe.rs:7:18: 7:48 lua:&mlua::lua::Lua]`

tests/compile_fail/ref_nounwindsafe.stderr

@@ -1,48 +0,0 @@
-error[E0277]: the type `std::cell::UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-   --> $DIR/ref_nounwindsafe.rs:8:5
-    |
-8   |     catch_unwind(move || table.set("a", "b").unwrap());
-    |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<()>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-    |
-    = help: within `mlua::lua::Lua`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<()>`
-    = note: required because it appears within the type `std::marker::PhantomData<std::cell::UnsafeCell<()>>`
-    = note: required because it appears within the type `mlua::lua::Lua`
-    = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&mlua::lua::Lua`
-    = note: required because it appears within the type `mlua::types::LuaRef<'_>`
-    = note: required because it appears within the type `mlua::table::Table<'_>`
-    = note: required because it appears within the type `[closure@$DIR/tests/compile_fail/ref_nounwindsafe.rs:8:18: 8:54 table:mlua::table::Table<'_>]`
-
-error[E0277]: the type `std::cell::UnsafeCell<mlua::lua::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-   --> $DIR/ref_nounwindsafe.rs:8:5
-    |
-8   |     catch_unwind(move || table.set("a", "b").unwrap());
-    |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<mlua::lua::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-    |
-    = help: within `mlua::lua::Lua`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<mlua::lua::ExtraData>`
-    = note: required because it appears within the type `std::cell::RefCell<mlua::lua::ExtraData>`
-    = note: required because it appears within the type `alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `std::marker::PhantomData<alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>>`
-    = note: required because it appears within the type `std::sync::Arc<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `mlua::lua::Lua`
-    = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&mlua::lua::Lua`
-    = note: required because it appears within the type `mlua::types::LuaRef<'_>`
-    = note: required because it appears within the type `mlua::table::Table<'_>`
-    = note: required because it appears within the type `[closure@$DIR/tests/compile_fail/ref_nounwindsafe.rs:8:18: 8:54 table:mlua::table::Table<'_>]`
-
-error[E0277]: the type `std::cell::UnsafeCell<isize>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-   --> $DIR/ref_nounwindsafe.rs:8:5
-    |
-8   |     catch_unwind(move || table.set("a", "b").unwrap());
-    |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<isize>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-    |
-    = help: within `mlua::lua::Lua`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<isize>`
-    = note: required because it appears within the type `std::cell::Cell<isize>`
-    = note: required because it appears within the type `std::cell::RefCell<mlua::lua::ExtraData>`
-    = note: required because it appears within the type `alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `std::marker::PhantomData<alloc::sync::ArcInner<std::cell::RefCell<mlua::lua::ExtraData>>>`
-    = note: required because it appears within the type `std::sync::Arc<std::cell::RefCell<mlua::lua::ExtraData>>`
-    = note: required because it appears within the type `mlua::lua::Lua`
-    = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&mlua::lua::Lua`
-    = note: required because it appears within the type `mlua::types::LuaRef<'_>`
-    = note: required because it appears within the type `mlua::table::Table<'_>`
-    = note: required because it appears within the type `[closure@$DIR/tests/compile_fail/ref_nounwindsafe.rs:8:18: 8:54 table:mlua::table::Table<'_>]`

tests/compile_fail/scope_callback_capture.stderr

@@ -1,45 +0,0 @@
-error[E0495]: cannot infer an appropriate lifetime for autoref due to conflicting requirements
-  --> $DIR/scope_callback_capture.rs:12:14
-   |
-12 |             .create_function_mut(move |lua, t: Table| {
-   |              ^^^^^^^^^^^^^^^^^^^
-   |
-note: first, the lifetime cannot outlive the anonymous lifetime #2 defined on the body at 9:15...
-  --> $DIR/scope_callback_capture.rs:9:15
-   |
-9  |       lua.scope(|scope| -> Result<()> {
-   |  _______________^
-10 | |         let mut inner: Option<Table> = None;
-11 | |         let f = scope
-12 | |             .create_function_mut(move |lua, t: Table| {
-...  |
-20 | |         Ok(())
-21 | |     });
-   | |_____^
-note: ...so that reference does not outlive borrowed content
-  --> $DIR/scope_callback_capture.rs:11:17
-   |
-11 |         let f = scope
-   |                 ^^^^^
-note: but, the lifetime must be valid for the method call at 9:5...
-  --> $DIR/scope_callback_capture.rs:9:5
-   |
-9  | /     lua.scope(|scope| -> Result<()> {
-10 | |         let mut inner: Option<Table> = None;
-11 | |         let f = scope
-12 | |             .create_function_mut(move |lua, t: Table| {
-...  |
-20 | |         Ok(())
-21 | |     });
-   | |______^
-note: ...so that a type/lifetime parameter is in scope here
-  --> $DIR/scope_callback_capture.rs:9:5
-   |
-9  | /     lua.scope(|scope| -> Result<()> {
-10 | |         let mut inner: Option<Table> = None;
-11 | |         let f = scope
-12 | |             .create_function_mut(move |lua, t: Table| {
-...  |
-20 | |         Ok(())
-21 | |     });
-   | |______^

tests/compile_fail/scope_callback_inner.stderr

@@ -1,45 +0,0 @@
-error[E0495]: cannot infer an appropriate lifetime for autoref due to conflicting requirements
-  --> $DIR/scope_callback_inner.rs:12:14
-   |
-12 |             .create_function_mut(|_, t: Table| {
-   |              ^^^^^^^^^^^^^^^^^^^
-   |
-note: first, the lifetime cannot outlive the anonymous lifetime #2 defined on the body at 9:15...
-  --> $DIR/scope_callback_inner.rs:9:15
-   |
-9  |       lua.scope(|scope| -> Result<()> {
-   |  _______________^
-10 | |         let mut inner: Option<Table> = None;
-11 | |         let f = scope
-12 | |             .create_function_mut(|_, t: Table| {
-...  |
-17 | |         Ok(())
-18 | |     });
-   | |_____^
-note: ...so that reference does not outlive borrowed content
-  --> $DIR/scope_callback_inner.rs:11:17
-   |
-11 |         let f = scope
-   |                 ^^^^^
-note: but, the lifetime must be valid for the method call at 9:5...
-  --> $DIR/scope_callback_inner.rs:9:5
-   |
-9  | /     lua.scope(|scope| -> Result<()> {
-10 | |         let mut inner: Option<Table> = None;
-11 | |         let f = scope
-12 | |             .create_function_mut(|_, t: Table| {
-...  |
-17 | |         Ok(())
-18 | |     });
-   | |______^
-note: ...so that a type/lifetime parameter is in scope here
-  --> $DIR/scope_callback_inner.rs:9:5
-   |
-9  | /     lua.scope(|scope| -> Result<()> {
-10 | |         let mut inner: Option<Table> = None;
-11 | |         let f = scope
-12 | |             .create_function_mut(|_, t: Table| {
-...  |
-17 | |         Ok(())
-18 | |     });
-   | |______^

tests/compile_fail/scope_callback_outer.stderr

@@ -1,11 +0,0 @@
-error: borrowed data cannot be stored outside of its closure
-  --> $DIR/scope_callback_outer.rs:11:17
-   |
-9  |     let mut outer: Option<Table> = None;
-   |         --------- ...so that variable is valid at time of its declaration
-10 |     lua.scope(|scope| -> Result<()> {
-   |               --------------------- borrowed data cannot outlive this closure
-11 |         let f = scope
-   |                 ^^^^^ cannot be stored outside of its closure
-12 |             .create_function_mut(|_, t: Table| {
-   |              ------------------- cannot infer an appropriate lifetime...

tests/conversion.rs

@@ -0,0 +1,114 @@
+use std::borrow::Cow;
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
+use std::ffi::CString;
+
+use maplit::{btreemap, btreeset, hashmap, hashset};
+use mlua::{Lua, Result};
+
+#[test]
+fn test_conv_vec() -> Result<()> {
+    let lua = Lua::new();
+
+    let v = vec![1, 2, 3];
+    lua.globals().set("v", v.clone())?;
+    let v2: Vec<i32> = lua.globals().get("v")?;
+    assert!(v == v2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_hashmap() -> Result<()> {
+    let lua = Lua::new();
+
+    let map = hashmap! {"hello".to_string() => "world".to_string()};
+    lua.globals().set("map", map.clone())?;
+    let map2: HashMap<String, String> = lua.globals().get("map")?;
+    assert!(map == map2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_hashset() -> Result<()> {
+    let lua = Lua::new();
+
+    let set = hashset! {"hello".to_string(), "world".to_string()};
+    lua.globals().set("set", set.clone())?;
+    let set2: HashSet<String> = lua.globals().get("set")?;
+    assert!(set == set2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_btreemap() -> Result<()> {
+    let lua = Lua::new();
+
+    let map = btreemap! {"hello".to_string() => "world".to_string()};
+    lua.globals().set("map", map.clone())?;
+    let map2: BTreeMap<String, String> = lua.globals().get("map")?;
+    assert!(map == map2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_btreeset() -> Result<()> {
+    let lua = Lua::new();
+
+    let set = btreeset! {"hello".to_string(), "world".to_string()};
+    lua.globals().set("set", set.clone())?;
+    let set2: BTreeSet<String> = lua.globals().get("set")?;
+    assert!(set == set2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_cstring() -> Result<()> {
+    let lua = Lua::new();
+
+    let s = CString::new(b"hello".to_vec()).unwrap();
+    lua.globals().set("s", s.clone())?;
+    let s2: CString = lua.globals().get("s")?;
+    assert!(s == s2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_cow() -> Result<()> {
+    let lua = Lua::new();
+
+    let s = Cow::from("hello");
+    lua.globals().set("s", s.clone())?;
+    let s2: String = lua.globals().get("s")?;
+    assert!(s == s2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_boxed_str() -> Result<()> {
+    let lua = Lua::new();
+
+    let s = String::from("hello").into_boxed_str();
+    lua.globals().set("s", s.clone())?;
+    let s2: Box<str> = lua.globals().get("s")?;
+    assert!(s == s2);
+
+    Ok(())
+}
+
+#[test]
+fn test_conv_boxed_slice() -> Result<()> {
+    let lua = Lua::new();
+
+    let v = vec![1, 2, 3].into_boxed_slice();
+    lua.globals().set("v", v.clone())?;
+    let v2: Box<[i32]> = lua.globals().get("v")?;
+    assert!(v == v2);
+
+    Ok(())
+}

tests/function.rs

@@ -75,3 +75,17 @@ fn test_rust_function() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_dump() -> Result<()> {
+    let lua = unsafe { Lua::unsafe_new() };
+
+    let concat_lua = lua
+        .load(r#"function(arg1, arg2) return arg1 .. arg2 end"#)
+        .eval::<Function>()?;
+    let concat = lua.load(&concat_lua.dump(false)).into_function()?;
+
+    assert_eq!(concat.call::<_, String>(("foo", "bar"))?, "foobar");
+
+    Ok(())
+}

tests/hooks.rs

@@ -0,0 +1,249 @@
+use std::cell::RefCell;
+use std::ops::Deref;
+use std::str;
+use std::sync::{Arc, Mutex};
+
+use mlua::{Error, HookTriggers, Lua, Result, Value};
+
+#[test]
+fn line_counts() -> Result<()> {
+    let output = Arc::new(Mutex::new(Vec::new()));
+    let hook_output = output.clone();
+
+    let lua = Lua::new();
+    lua.set_hook(
+        HookTriggers {
+            every_line: true,
+            ..Default::default()
+        },
+        move |_lua, debug| {
+            hook_output.lock().unwrap().push(debug.curr_line());
+            Ok(())
+        },
+    )?;
+    lua.load(
+        r#"
+            local x = 2 + 3
+            local y = x * 63
+            local z = string.len(x..", "..y)
+        "#,
+    )
+    .exec()?;
+
+    lua.remove_hook();
+
+    let output = output.lock().unwrap();
+    if cfg!(feature = "luajit") && lua.load("jit.version_num").eval::<i64>()? >= 20100 {
+        assert_eq!(*output, vec![2, 3, 4, 0, 4]);
+    } else {
+        assert_eq!(*output, vec![2, 3, 4]);
+    }
+
+    Ok(())
+}
+
+#[test]
+fn function_calls() -> Result<()> {
+    let output = Arc::new(Mutex::new(Vec::new()));
+    let hook_output = output.clone();
+
+    let lua = Lua::new();
+    lua.set_hook(
+        HookTriggers {
+            on_calls: true,
+            ..Default::default()
+        },
+        move |_lua, debug| {
+            let names = debug.names();
+            let source = debug.source();
+            let name = names.name.map(|s| str::from_utf8(s).unwrap().to_owned());
+            let what = source.what.map(|s| str::from_utf8(s).unwrap().to_owned());
+            hook_output.lock().unwrap().push((name, what));
+            Ok(())
+        },
+    )?;
+
+    lua.load(
+        r#"
+            local v = string.len("Hello World")
+        "#,
+    )
+    .exec()?;
+
+    lua.remove_hook();
+
+    let output = output.lock().unwrap();
+    if cfg!(feature = "luajit") && lua.load("jit.version_num").eval::<i64>()? >= 20100 {
+        assert_eq!(
+            *output,
+            vec![
+                (None, Some("main".to_string())),
+                (Some("len".to_string()), Some("Lua".to_string()))
+            ]
+        );
+    } else {
+        assert_eq!(
+            *output,
+            vec![
+                (None, Some("main".to_string())),
+                (Some("len".to_string()), Some("C".to_string()))
+            ]
+        );
+    }
+
+    Ok(())
+}
+
+#[test]
+fn error_within_hook() -> Result<()> {
+    let lua = Lua::new();
+    lua.set_hook(
+        HookTriggers {
+            every_line: true,
+            ..Default::default()
+        },
+        |_lua, _debug| {
+            Err(Error::RuntimeError(
+                "Something happened in there!".to_string(),
+            ))
+        },
+    )?;
+
+    let err = lua
+        .load("x = 1")
+        .exec()
+        .expect_err("panic didn't propagate");
+
+    match err {
+        Error::CallbackError { cause, .. } => match cause.deref() {
+            Error::RuntimeError(s) => assert_eq!(s, "Something happened in there!"),
+            _ => panic!("wrong callback error kind caught"),
+        },
+        _ => panic!("wrong error kind caught"),
+    };
+
+    Ok(())
+}
+
+#[test]
+fn limit_execution_instructions() -> Result<()> {
+    let lua = Lua::new();
+    let mut max_instructions = 10000;
+
+    #[cfg(feature = "luajit")]
+    // For LuaJIT disable JIT, as compiled code does not trigger hooks
+    lua.load("jit.off()").exec()?;
+
+    lua.set_hook(
+        HookTriggers {
+            every_nth_instruction: Some(30),
+            ..Default::default()
+        },
+        move |_lua, _debug| {
+            max_instructions -= 30;
+            if max_instructions < 0 {
+                Err(Error::RuntimeError("time's up".to_string()))
+            } else {
+                Ok(())
+            }
+        },
+    )?;
+
+    lua.globals().set("x", Value::Integer(0))?;
+    let _ = lua
+        .load(
+            r#"
+                for i = 1, 10000 do
+                    x = x + 1
+                end
+            "#,
+        )
+        .exec()
+        .expect_err("instruction limit didn't occur");
+
+    Ok(())
+}
+
+#[test]
+fn hook_removal() -> Result<()> {
+    let lua = Lua::new();
+
+    lua.set_hook(
+        HookTriggers {
+            every_nth_instruction: Some(1),
+            ..Default::default()
+        },
+        |_lua, _debug| {
+            Err(Error::RuntimeError(
+                "this hook should've been removed by this time".to_string(),
+            ))
+        },
+    )?;
+
+    assert!(lua.load("local x = 1").exec().is_err());
+    lua.remove_hook();
+    assert!(lua.load("local x = 1").exec().is_ok());
+
+    Ok(())
+}
+
+#[test]
+fn hook_swap_within_hook() -> Result<()> {
+    thread_local! {
+        static TL_LUA: RefCell<Option<Lua>> = RefCell::new(None);
+    }
+
+    TL_LUA.with(|tl| {
+        *tl.borrow_mut() = Some(Lua::new());
+    });
+
+    TL_LUA.with(|tl| {
+        tl.borrow().as_ref().unwrap().set_hook(
+            HookTriggers {
+                every_line: true,
+                ..Default::default()
+            },
+            move |lua, _debug| {
+                lua.globals().set("ok", 1i64)?;
+                TL_LUA.with(|tl| {
+                    tl.borrow().as_ref().unwrap().set_hook(
+                        HookTriggers {
+                            every_line: true,
+                            ..Default::default()
+                        },
+                        move |lua, _debug| {
+                            lua.load(
+                                r#"
+                                    if ok ~= nil then
+                                        ok = ok + 1
+                                    end
+                                "#,
+                            )
+                            .exec()
+                            .expect("exec failure within hook");
+                            TL_LUA.with(|tl| {
+                                tl.borrow().as_ref().unwrap().remove_hook();
+                            });
+                            Ok(())
+                        },
+                    )
+                })
+            },
+        )
+    })?;
+
+    TL_LUA.with(|tl| {
+        let tl = tl.borrow();
+        let lua = tl.as_ref().unwrap();
+        lua.load(
+            r#"
+                local x = 1
+                x = 2
+                local y = 3
+            "#,
+        )
+        .exec()?;
+        assert_eq!(lua.globals().get::<_, i64>("ok")?, 2);
+        Ok(())
+    })
+}

tests/memory.rs

@@ -2,12 +2,43 @@ use std::sync::Arc;
 
 use mlua::{Lua, Result, UserData};
 
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+use mlua::Error;
+
+#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+#[test]
+fn test_memory_limit() -> Result<()> {
+    let lua = Lua::new();
+
+    let initial_memory = lua.used_memory();
+    assert!(
+        initial_memory > 0,
+        "used_memory reporting is wrong, lua uses memory for stdlib"
+    );
+
+    let f = lua
+        .load("local t = {}; for i = 1,10000 do t[i] = i end")
+        .into_function()?;
+    f.call::<_, ()>(()).expect("should trigger no memory limit");
+
+    lua.set_memory_limit(initial_memory + 10000)?;
+    match f.call::<_, ()>(()) {
+        Err(Error::MemoryError(_)) => {}
+        something_else => panic!("did not trigger memory error: {:?}", something_else),
+    };
+
+    lua.set_memory_limit(0)?;
+    f.call::<_, ()>(()).expect("should trigger no memory limit");
+
+    Ok(())
+}
+
 #[test]
 fn test_gc_control() -> Result<()> {
     let lua = Lua::new();
     let globals = lua.globals();
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     {
         assert!(lua.gc_is_running());
         lua.gc_stop();

tests/module/.cargo/config

@@ -0,0 +1,5 @@
+[target.x86_64-apple-darwin]
+rustflags = ["-C", "link-args=-rdynamic"]
+
+[target.x86_64-unknown-linux-gnu]
+rustflags = ["-C", "link-args=-rdynamic"]

tests/module/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "module_runner"
+version = "0.0.0"
+authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
+edition = "2018"
+
+[features]
+lua54 = ["mlua/lua54"]
+lua53 = ["mlua/lua53"]
+lua52 = ["mlua/lua52"]
+lua51 = ["mlua/lua51"]
+luajit = ["mlua/luajit"]
+vendored = ["mlua/vendored"]
+
+[dependencies]
+mlua = { path = "../.." }

tests/module/tests/load.rs

@@ -0,0 +1,82 @@
+use std::env;
+use std::path::PathBuf;
+
+use mlua::{Lua, Result};
+
+#[test]
+fn test_module() -> Result<()> {
+    let lua = make_lua()?;
+    lua.load(
+        r#"
+        local mod = require("rust_module")
+        assert(mod.sum(2,2) == 4)
+    "#,
+    )
+    .exec()
+}
+
+#[cfg(any(
+    feature = "lua54",
+    feature = "lua53",
+    feature = "lua52",
+    feature = "lua51"
+))]
+#[test]
+fn test_module_from_thread() -> Result<()> {
+    let lua = make_lua()?;
+    lua.load(
+        r#"
+        local mod
+
+        local co = coroutine.create(function(a, b)
+            mod = require("rust_module")
+            assert(mod.sum(a, b) == a + b)
+        end)
+
+        coroutine.resume(co, 3, 5)
+        collectgarbage()
+
+        assert(mod.used_memory() > 0)
+    "#,
+    )
+    .exec()
+}
+
+fn make_lua() -> Result<Lua> {
+    let (dylib_path, dylib_ext, separator);
+    if cfg!(target_os = "macos") {
+        dylib_path = env::var("DYLD_FALLBACK_LIBRARY_PATH").unwrap();
+        dylib_ext = "dylib";
+        separator = ":";
+    } else if cfg!(target_os = "linux") {
+        dylib_path = env::var("LD_LIBRARY_PATH").unwrap();
+        dylib_ext = "so";
+        separator = ":";
+    } else if cfg!(target_os = "windows") {
+        dylib_path = env::var("PATH").unwrap();
+        dylib_ext = "dll";
+        separator = ";";
+    } else {
+        panic!("unknown target os");
+    };
+
+    let mut cpath = dylib_path
+        .split(separator)
+        .take(3)
+        .map(|p| {
+            let mut path = PathBuf::from(p);
+            path.push(format!("lib?.{}", dylib_ext));
+            path.to_str().unwrap().to_owned()
+        })
+        .collect::<Vec<_>>()
+        .join(";");
+
+    if cfg!(target_os = "windows") {
+        cpath = cpath.replace("\\", "\\\\");
+        cpath = cpath.replace("lib?.", "?.");
+    }
+
+    let lua = unsafe { Lua::unsafe_new() }; // To be able to load C modules
+    lua.load(&format!("package.cpath = \"{}\"", cpath)).exec()?;
+    Ok(lua)
+}

tests/scope.rs

@@ -1,7 +1,11 @@
 use std::cell::Cell;
 use std::rc::Rc;
+use std::sync::Arc;
 
-use mlua::{Error, Function, Lua, MetaMethod, Result, String, UserData, UserDataMethods};
+use mlua::{
+    AnyUserData, Error, Function, Lua, MetaMethod, Result, String, UserData, UserDataFields,
+    UserDataMethods,
+};
 
 #[test]
 fn scope_func() -> Result<()> {
@@ -23,44 +27,16 @@ fn scope_func() -> Result<()> {
     assert_eq!(Rc::strong_count(&rc), 1);
 
     match lua.globals().get::<_, Function>("bad")?.call::<_, ()>(()) {
-        Err(Error::CallbackError { .. }) => {}
+        Err(Error::CallbackError { ref cause, .. }) => match *cause.as_ref() {
+            Error::CallbackDestructed => {}
+            ref err => panic!("wrong error type {:?}", err),
+        },
         r => panic!("improper return for destructed function: {:?}", r),
     };
 
     Ok(())
 }
 
-#[test]
-fn scope_drop() -> Result<()> {
-    let lua = Lua::new();
-
-    struct MyUserdata(Rc<()>);
-    impl UserData for MyUserdata {
-        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
-            methods.add_method("method", |_, _, ()| Ok(()));
-        }
-    }
-
-    let rc = Rc::new(());
-
-    lua.scope(|scope| {
-        lua.globals().set(
-            "test",
-            scope.create_static_userdata(MyUserdata(rc.clone()))?,
-        )?;
-        assert_eq!(Rc::strong_count(&rc), 2);
-        Ok(())
-    })?;
-    assert_eq!(Rc::strong_count(&rc), 1);
-
-    match lua.load("test:method()").exec() {
-        Err(Error::CallbackError { .. }) => {}
-        r => panic!("improper return for destructed userdata: {:?}", r),
-    };
-
-    Ok(())
-}
-
 #[test]
 fn scope_capture() -> Result<()> {
     let lua = Lua::new();
@@ -80,7 +56,7 @@ fn scope_capture() -> Result<()> {
 }
 
 #[test]
-fn outer_lua_access() -> Result<()> {
+fn scope_outer_lua_access() -> Result<()> {
     let lua = Lua::new();
 
     let table = lua.create_table()?;
@@ -94,6 +70,41 @@ fn outer_lua_access() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn scope_userdata_fields() -> Result<()> {
+    struct MyUserData<'a>(&'a Cell<i64>);
+
+    impl<'a> UserData for MyUserData<'a> {
+        fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+            fields.add_field_method_get("val", |_, data| Ok(data.0.get()));
+            fields.add_field_method_set("val", |_, data, val| {
+                data.0.set(val);
+                Ok(())
+            });
+        }
+    }
+
+    let lua = Lua::new();
+
+    let i = Cell::new(42);
+    let f: Function = lua
+        .load(
+            r#"
+            function(u)
+                assert(u.val == 42)
+                u.val = 44
+            end
+        "#,
+        )
+        .eval()?;
+
+    lua.scope(|scope| f.call::<_, ()>(scope.create_nonstatic_userdata(MyUserData(&i))?))?;
+
+    assert_eq!(i.get(), 44);
+
+    Ok(())
+}
+
 #[test]
 fn scope_userdata_methods() -> Result<()> {
     struct MyUserData<'a>(&'a Cell<i64>);
@@ -198,7 +209,6 @@ fn scope_userdata_mismatch() -> Result<()> {
             a.inc(a)
             b.inc(b)
         end
-
         function bad(a, b)
             a.inc(b)
         end
@@ -229,3 +239,120 @@ fn scope_userdata_mismatch() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn scope_userdata_drop() -> Result<()> {
+    let lua = Lua::new();
+
+    struct MyUserData(Rc<()>);
+
+    impl UserData for MyUserData {
+        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_method("method", |_, _, ()| Ok(()));
+        }
+    }
+
+    struct MyUserDataArc(Arc<()>);
+
+    impl UserData for MyUserDataArc {}
+
+    let rc = Rc::new(());
+    let arc = Arc::new(());
+    lua.scope(|scope| {
+        let ud = scope.create_userdata(MyUserData(rc.clone()))?;
+        ud.set_user_value(MyUserDataArc(arc.clone()))?;
+        lua.globals().set("ud", ud)?;
+        assert_eq!(Rc::strong_count(&rc), 2);
+        assert_eq!(Arc::strong_count(&arc), 2);
+        Ok(())
+    })?;
+
+    lua.gc_collect()?;
+    assert_eq!(Rc::strong_count(&rc), 1);
+    assert_eq!(Arc::strong_count(&arc), 1);
+
+    match lua.load("ud:method()").exec() {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::CallbackDestructed => {}
+            err => panic!("expected CallbackDestructed, got {:?}", err),
+        },
+        r => panic!("improper return for destructed userdata: {:?}", r),
+    };
+
+    let ud = lua.globals().get::<_, AnyUserData>("ud")?;
+    match ud.borrow::<MyUserData>() {
+        Ok(_) => panic!("succesfull borrow for destructed userdata"),
+        Err(Error::UserDataDestructed) => {}
+        Err(err) => panic!("improper borrow error for destructed userdata: {:?}", err),
+    }
+
+    match ud.get_metatable() {
+        Ok(_) => panic!("successful metatable retrieval of destructed userdata"),
+        Err(Error::UserDataDestructed) => {}
+        Err(err) => panic!(
+            "improper metatable error for destructed userdata: {:?}",
+            err
+        ),
+    }
+
+    Ok(())
+}
+
+#[test]
+fn scope_nonstatic_userdata_drop() -> Result<()> {
+    let lua = Lua::new();
+
+    struct MyUserData<'a>(&'a Cell<i64>, Arc<()>);
+
+    impl<'a> UserData for MyUserData<'a> {
+        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_method("inc", |_, data, ()| {
+                data.0.set(data.0.get() + 1);
+                Ok(())
+            });
+        }
+    }
+
+    struct MyUserDataArc(Arc<()>);
+
+    impl UserData for MyUserDataArc {}
+
+    let i = Cell::new(1);
+    let arc = Arc::new(());
+    lua.scope(|scope| {
+        let ud = scope.create_nonstatic_userdata(MyUserData(&i, arc.clone()))?;
+        ud.set_user_value(MyUserDataArc(arc.clone()))?;
+        lua.globals().set("ud", ud)?;
+        lua.load("ud:inc()").exec()?;
+        assert_eq!(Arc::strong_count(&arc), 3);
+        Ok(())
+    })?;
+
+    lua.gc_collect()?;
+    assert_eq!(Arc::strong_count(&arc), 1);
+
+    match lua.load("ud:inc()").exec() {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::CallbackDestructed => {}
+            err => panic!("expected CallbackDestructed, got {:?}", err),
+        },
+        r => panic!("improper return for destructed userdata: {:?}", r),
+    };
+
+    let ud = lua.globals().get::<_, AnyUserData>("ud")?;
+    match ud.borrow::<MyUserData>() {
+        Ok(_) => panic!("succesfull borrow for destructed userdata"),
+        Err(Error::UserDataDestructed) => {}
+        Err(err) => panic!("improper borrow error for destructed userdata: {:?}", err),
+    }
+    match ud.get_metatable() {
+        Ok(_) => panic!("successful metatable retrieval of destructed userdata"),
+        Err(Error::UserDataDestructed) => {}
+        Err(err) => panic!(
+            "improper metatable error for destructed userdata: {:?}",
+            err
+        ),
+    }
+
+    Ok(())
+}

tests/serde.rs

@@ -0,0 +1,415 @@
+#![cfg(feature = "serialize")]
+
+use std::collections::HashMap;
+
+use mlua::{Error, Lua, LuaSerdeExt, Result as LuaResult, SerializeOptions, UserData, Value};
+use serde::{Deserialize, Serialize};
+
+#[test]
+fn test_serialize() -> Result<(), Box<dyn std::error::Error>> {
+    #[derive(Serialize)]
+    struct MyUserData(i64, String);
+
+    impl UserData for MyUserData {}
+
+    let lua = Lua::new();
+    let globals = lua.globals();
+
+    let ud = lua.create_ser_userdata(MyUserData(123, "test userdata".into()))?;
+    globals.set("ud", ud)?;
+    globals.set("null", lua.null())?;
+
+    let empty_array = lua.create_table()?;
+    empty_array.set_metatable(Some(lua.array_metatable()));
+    globals.set("empty_array", empty_array)?;
+
+    let val = lua
+        .load(
+            r#"
+        {
+            _bool = true,
+            _integer = 123,
+            _number = 321.99,
+            _string = "test string serialization",
+            _table_arr = {nil, "value 1", nil, "value 2", {}},
+            _table_map = {["table"] = "map", ["null"] = null},
+            _bytes = "\240\040\140\040",
+            _userdata = ud,
+            _null = null,
+            _empty_map = {},
+            _empty_array = empty_array,
+        }
+    "#,
+        )
+        .eval::<Value>()?;
+
+    let json = serde_json::json!({
+        "_bool": true,
+        "_integer": 123,
+        "_number": 321.99,
+        "_string": "test string serialization",
+        "_table_arr": [null, "value 1", null, "value 2", {}],
+        "_table_map": {"table": "map", "null": null},
+        "_bytes": [240, 40, 140, 40],
+        "_userdata": [123, "test userdata"],
+        "_null": null,
+        "_empty_map": {},
+        "_empty_array": [],
+    });
+
+    assert_eq!(serde_json::to_value(&val)?, json);
+
+    // Test to-from loop
+    let val = lua.to_value(&json)?;
+    let expected_json = lua.from_value::<serde_json::Value>(val)?;
+    assert_eq!(expected_json, json);
+
+    Ok(())
+}
+
+#[test]
+fn test_serialize_in_scope() -> LuaResult<()> {
+    #[derive(Serialize, Clone)]
+    struct MyUserData(i64, String);
+
+    impl UserData for MyUserData {}
+
+    let lua = Lua::new();
+    lua.scope(|scope| {
+        let ud = scope.create_ser_userdata(MyUserData(-5, "test userdata".into()))?;
+        assert_eq!(
+            serde_json::to_value(&ud).unwrap(),
+            serde_json::json!((-5, "test userdata"))
+        );
+        Ok(())
+    })?;
+
+    lua.scope(|scope| {
+        let ud = scope.create_ser_userdata(MyUserData(-5, "test userdata".into()))?;
+        lua.globals().set("ud", ud)
+    })?;
+    let val = lua.load("ud").eval::<Value>()?;
+    match serde_json::to_value(&val) {
+        Ok(v) => panic!("expected destructed error, got {}", v),
+        Err(e) if e.to_string().contains("destructed") => {}
+        Err(e) => panic!("expected destructed error, got {}", e),
+    }
+
+    struct MyUserDataRef<'a>(&'a ());
+
+    impl<'a> UserData for MyUserDataRef<'a> {}
+
+    lua.scope(|scope| {
+        let ud = scope.create_nonstatic_userdata(MyUserDataRef(&()))?;
+        match serde_json::to_value(&ud) {
+            Ok(v) => panic!("expected serialization error, got {}", v),
+            Err(serde_json::Error { .. }) => {}
+        };
+        Ok(())
+    })?;
+
+    Ok(())
+}
+
+#[test]
+fn test_serialize_failure() -> Result<(), Box<dyn std::error::Error>> {
+    #[derive(Serialize)]
+    struct MyUserData(i64);
+
+    impl UserData for MyUserData {}
+
+    let lua = Lua::new();
+
+    let ud = Value::UserData(lua.create_userdata(MyUserData(123))?);
+    match serde_json::to_value(&ud) {
+        Ok(v) => panic!("expected serialization error, got {}", v),
+        Err(serde_json::Error { .. }) => {}
+    }
+
+    let func = lua.create_function(|_, _: ()| Ok(()))?;
+    match serde_json::to_value(&Value::Function(func.clone())) {
+        Ok(v) => panic!("expected serialization error, got {}", v),
+        Err(serde_json::Error { .. }) => {}
+    }
+
+    let thr = lua.create_thread(func)?;
+    match serde_json::to_value(&Value::Thread(thr)) {
+        Ok(v) => panic!("expected serialization error, got {}", v),
+        Err(serde_json::Error { .. }) => {}
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_to_value_struct() -> LuaResult<()> {
+    let lua = Lua::new();
+    let globals = lua.globals();
+    globals.set("null", lua.null())?;
+
+    #[derive(Serialize)]
+    struct Test {
+        name: String,
+        key: i64,
+        data: Option<bool>,
+    }
+
+    let test = Test {
+        name: "alex".to_string(),
+        key: -16,
+        data: None,
+    };
+
+    globals.set("value", lua.to_value(&test)?)?;
+    lua.load(
+        r#"
+            assert(value["name"] == "alex")
+            assert(value["key"] == -16)
+            assert(value["data"] == null)
+        "#,
+    )
+    .exec()
+}
+
+#[test]
+fn test_to_value_enum() -> LuaResult<()> {
+    let lua = Lua::new();
+    let globals = lua.globals();
+    globals.set("null", lua.null())?;
+
+    #[derive(Serialize)]
+    struct Test {
+        name: String,
+        key: i64,
+        data: Option<bool>,
+    }
+
+    let test = Test {
+        name: "alex".to_string(),
+        key: -16,
+        data: None,
+    };
+
+    globals.set("value", lua.to_value(&test)?)?;
+    lua.load(
+        r#"
+            assert(value["name"] == "alex")
+            assert(value["key"] == -16)
+            assert(value["data"] == null)
+        "#,
+    )
+    .exec()?;
+
+    #[derive(Serialize)]
+    enum E {
+        Unit,
+        Integer(u32),
+        Tuple(u32, u32),
+        Struct { a: u32 },
+    }
+
+    let u = E::Unit;
+    globals.set("value", lua.to_value(&u)?)?;
+    lua.load(r#"assert(value == "Unit")"#).exec()?;
+
+    let n = E::Integer(1);
+    globals.set("value", lua.to_value(&n)?)?;
+    lua.load(r#"assert(value["Integer"] == 1)"#).exec()?;
+
+    let t = E::Tuple(1, 2);
+    globals.set("value", lua.to_value(&t)?)?;
+    lua.load(
+        r#"
+            assert(value["Tuple"][1] == 1)
+            assert(value["Tuple"][2] == 2)
+        "#,
+    )
+    .exec()?;
+
+    let s = E::Struct { a: 1 };
+    globals.set("value", lua.to_value(&s)?)?;
+    lua.load(r#"assert(value["Struct"]["a"] == 1)"#).exec()?;
+    Ok(())
+}
+
+#[test]
+fn test_to_value_with_options() -> Result<(), Box<dyn std::error::Error>> {
+    let lua = Lua::new();
+    let globals = lua.globals();
+    globals.set("null", lua.null())?;
+
+    // set_array_metatable
+    let data = lua.to_value_with(
+        &Vec::<i32>::new(),
+        SerializeOptions::new().set_array_metatable(false),
+    )?;
+    globals.set("data", data)?;
+    lua.load(
+        r#"
+        assert(type(data) == "table" and #data == 0)
+        assert(getmetatable(data) == nil)
+    "#,
+    )
+    .exec()?;
+
+    #[derive(Serialize)]
+    struct UnitStruct;
+
+    #[derive(Serialize)]
+    struct MyData {
+        map: HashMap<&'static str, Option<i32>>,
+        unit: (),
+        unitstruct: UnitStruct,
+    }
+
+    // serialize_none_to_null
+    let mut map = HashMap::new();
+    map.insert("key", None);
+    let mydata = MyData {
+        map,
+        unit: (),
+        unitstruct: UnitStruct,
+    };
+    let data2 = lua.to_value_with(
+        &mydata,
+        SerializeOptions::new().serialize_none_to_null(false),
+    )?;
+    globals.set("data2", data2)?;
+    lua.load(
+        r#"
+        assert(data2.map.key == nil)
+        assert(data2.unit == null)
+        assert(data2.unitstruct == null)
+    "#,
+    )
+    .exec()?;
+
+    // serialize_unit_to_null
+    let data3 = lua.to_value_with(
+        &mydata,
+        SerializeOptions::new().serialize_unit_to_null(false),
+    )?;
+    globals.set("data3", data3)?;
+    lua.load(
+        r#"
+        assert(data3.map.key == null)
+        assert(data3.unit == nil)
+        assert(data3.unitstruct == nil)
+    "#,
+    )
+    .exec()?;
+
+    Ok(())
+}
+
+#[test]
+fn test_from_value_struct() -> Result<(), Box<dyn std::error::Error>> {
+    let lua = Lua::new();
+
+    #[derive(Deserialize, PartialEq, Debug)]
+    struct Test {
+        int: u32,
+        seq: Vec<String>,
+        map: std::collections::HashMap<i32, i32>,
+        empty: Vec<()>,
+        tuple: (u8, u8, u8),
+    }
+
+    let value = lua
+        .load(
+            r#"
+            {
+                int = 1,
+                seq = {"a", "b"},
+                map = {2, [4] = 1},
+                empty = {},
+                tuple = {10, 20, 30},
+            }
+        "#,
+        )
+        .eval::<Value>()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(
+        Test {
+            int: 1,
+            seq: vec!["a".into(), "b".into()],
+            map: vec![(1, 2), (4, 1)].into_iter().collect(),
+            empty: vec![],
+            tuple: (10, 20, 30),
+        },
+        got
+    );
+
+    Ok(())
+}
+
+#[test]
+fn test_from_value_enum() -> Result<(), Box<dyn std::error::Error>> {
+    let lua = Lua::new();
+
+    #[derive(Deserialize, PartialEq, Debug)]
+    enum E {
+        Unit,
+        Integer(u32),
+        Tuple(u32, u32),
+        Struct { a: u32 },
+    }
+
+    let value = lua.load(r#""Unit""#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(E::Unit, got);
+
+    let value = lua.load(r#"{Integer = 1}"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(E::Integer(1), got);
+
+    let value = lua.load(r#"{Tuple = {1, 2}}"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(E::Tuple(1, 2), got);
+
+    let value = lua.load(r#"{Struct = {a = 3}}"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(E::Struct { a: 3 }, got);
+
+    Ok(())
+}
+
+#[test]
+fn test_from_value_enum_untagged() -> Result<(), Box<dyn std::error::Error>> {
+    let lua = Lua::new();
+    lua.globals().set("null", lua.null())?;
+
+    #[derive(Deserialize, PartialEq, Debug)]
+    #[serde(untagged)]
+    enum Eut {
+        Unit,
+        Integer(u64),
+        Tuple(u32, u32),
+        Struct { a: u32 },
+    }
+
+    let value = lua.load(r#"null"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(Eut::Unit, got);
+
+    let value = lua.load(r#"1"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(Eut::Integer(1), got);
+
+    let value = lua.load(r#"{3, 1}"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(Eut::Tuple(3, 1), got);
+
+    let value = lua.load(r#"{a = 10}"#).eval()?;
+    let got = lua.from_value(value)?;
+    assert_eq!(Eut::Struct { a: 10 }, got);
+
+    let value = lua.load(r#"{b = 12}"#).eval()?;
+    match lua.from_value::<Eut>(value) {
+        Ok(v) => panic!("expected Error::DeserializeError, got {:?}", v),
+        Err(Error::DeserializeError(_)) => {}
+        Err(e) => panic!("expected Error::DeserializeError, got {}", e),
+    }
+
+    Ok(())
+}

tests/table.rs

@@ -1,4 +1,4 @@
-use mlua::{Lua, Nil, Result, Table, Value};
+use mlua::{Lua, Nil, Result, Table, TableExt, Value};
 
 #[test]
 fn test_set_get() -> Result<()> {
@@ -109,6 +109,47 @@ fn test_table() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_table_sequence_from() -> Result<()> {
+    let lua = Lua::new();
+
+    let get_table = lua.create_function(|_, t: Table| Ok(t))?;
+
+    assert_eq!(
+        get_table
+            .call::<_, Table>(vec![1, 2, 3])?
+            .sequence_values()
+            .collect::<Result<Vec<i64>>>()?,
+        vec![1, 2, 3]
+    );
+
+    assert_eq!(
+        get_table
+            .call::<_, Table>([1, 2, 3].as_ref())?
+            .sequence_values()
+            .collect::<Result<Vec<i64>>>()?,
+        vec![1, 2, 3]
+    );
+
+    assert_eq!(
+        get_table
+            .call::<_, Table>([1, 2, 3])?
+            .sequence_values()
+            .collect::<Result<Vec<i64>>>()?,
+        vec![1, 2, 3]
+    );
+
+    assert_eq!(
+        get_table
+            .call::<_, Table>(&[1, 2, 3])?
+            .sequence_values()
+            .collect::<Result<Vec<i64>>>()?,
+        vec![1, 2, 3]
+    );
+
+    Ok(())
+}
+
 #[test]
 fn test_table_scope() -> Result<()> {
     let lua = Lua::new();
@@ -226,3 +267,33 @@ fn test_table_error() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_table_call() -> Result<()> {
+    let lua = Lua::new();
+
+    lua.load(
+        r#"
+        table = {a = 1}
+
+        function table.func(key)
+            return "func_"..key
+        end
+
+        function table:method(key)
+            return "method_"..self[key]
+        end
+    "#,
+    )
+    .exec()?;
+
+    let table: Table = lua.globals().get("table")?;
+
+    assert_eq!(table.call_function::<_, _, String>("func", "a")?, "func_a");
+    assert_eq!(
+        table.call_method::<_, _, String>("method", "a")?,
+        "method_1"
+    );
+
+    Ok(())
+}

tests/tests.rs

@@ -1,12 +1,84 @@
 use std::iter::FromIterator;
-use std::panic::catch_unwind;
+use std::panic::{catch_unwind, AssertUnwindSafe};
+use std::string::String as StdString;
 use std::sync::Arc;
 use std::{error, f32, f64, fmt};
 
 use mlua::{
-    Error, ExternalError, Function, Lua, Nil, Result, String, Table, UserData, Value, Variadic,
+    ChunkMode, Error, ExternalError, Function, Lua, LuaOptions, Nil, Result, StdLib, String, Table,
+    UserData, Value, Variadic,
 };
 
+#[test]
+fn test_safety() -> Result<()> {
+    let lua = Lua::new();
+    assert!(lua.load(r#"require "debug""#).exec().is_err());
+    match lua.load_from_std_lib(StdLib::DEBUG) {
+        Err(Error::SafetyError(_)) => {}
+        Err(e) => panic!("expected SafetyError, got {:?}", e),
+        Ok(_) => panic!("expected SafetyError, got no error"),
+    }
+    drop(lua);
+
+    let lua = unsafe { Lua::unsafe_new() };
+    assert!(lua.load(r#"require "debug""#).exec().is_ok());
+    drop(lua);
+
+    match Lua::new_with(StdLib::DEBUG, LuaOptions::default()) {
+        Err(Error::SafetyError(_)) => {}
+        Err(e) => panic!("expected SafetyError, got {:?}", e),
+        Ok(_) => panic!("expected SafetyError, got new Lua state"),
+    }
+
+    let lua = Lua::new();
+    match lua.load(r#"package.loadlib()"#).exec() {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::SafetyError(_) => {}
+            e => panic!("expected SafetyError cause, got {:?}", e),
+        },
+        Err(e) => panic!("expected CallbackError, got {:?}", e),
+        Ok(_) => panic!("expected CallbackError, got no error"),
+    };
+    match lua.load(r#"require "fake_ffi""#).exec() {
+        Err(Error::RuntimeError(msg)) => assert!(msg.contains("can't load C modules in safe mode")),
+        Err(e) => panic!("expected RuntimeError, got {:?}", e),
+        Ok(_) => panic!("expected RuntimeError, got no error"),
+    }
+
+    match lua.load("1 + 1").set_mode(ChunkMode::Binary).exec() {
+        Err(Error::SafetyError(msg)) => {
+            assert!(msg.contains("binary chunks are disabled in safe mode"))
+        }
+        Err(e) => panic!("expected SafetyError, got {:?}", e),
+        Ok(_) => panic!("expected SafetyError, got no error"),
+    }
+
+    let bytecode = lua.load("return 1 + 1").into_function()?.dump(true);
+    match lua.load(&bytecode).exec() {
+        Err(Error::SafetyError(msg)) => {
+            assert!(msg.contains("binary chunks are disabled in safe mode"))
+        }
+        Err(e) => panic!("expected SafetyError, got {:?}", e),
+        Ok(_) => panic!("expected SafetyError, got no error"),
+    }
+    drop(lua);
+
+    // Test safety rules after dynamically loading `package` library
+    let lua = Lua::new_with(StdLib::NONE, LuaOptions::default())?;
+    assert!(lua.globals().get::<_, Option<Value>>("require")?.is_none());
+    lua.load_from_std_lib(StdLib::PACKAGE)?;
+    match lua.load(r#"package.loadlib()"#).exec() {
+        Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+            Error::SafetyError(_) => {}
+            e => panic!("expected SafetyError cause, got {:?}", e),
+        },
+        Err(e) => panic!("expected CallbackError, got {:?}", e),
+        Ok(_) => panic!("expected CallbackError, got no error"),
+    };
+
+    Ok(())
+}
+
 #[test]
 fn test_load() -> Result<()> {
     let lua = Lua::new();
@@ -75,6 +147,41 @@ fn test_eval() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_load_mode() -> Result<()> {
+    let lua = unsafe { Lua::unsafe_new() };
+
+    assert_eq!(
+        lua.load("1 + 1").set_mode(ChunkMode::Text).eval::<i32>()?,
+        2
+    );
+    match lua.load("1 + 1").set_mode(ChunkMode::Binary).exec() {
+        Ok(_) => panic!("expected SyntaxError, got no error"),
+        Err(Error::SyntaxError { message: msg, .. }) => {
+            assert!(msg.contains("attempt to load a text chunk"))
+        }
+        Err(e) => panic!("expected SyntaxError, got {:?}", e),
+    };
+
+    let bytecode = lua.load("return 1 + 1").into_function()?.dump(true);
+    assert_eq!(lua.load(&bytecode).eval::<i32>()?, 2);
+    assert_eq!(
+        lua.load(&bytecode)
+            .set_mode(ChunkMode::Binary)
+            .eval::<i32>()?,
+        2
+    );
+    match lua.load(&bytecode).set_mode(ChunkMode::Text).exec() {
+        Ok(_) => panic!("expected SyntaxError, got no error"),
+        Err(Error::SyntaxError { message: msg, .. }) => {
+            assert!(msg.contains("attempt to load a binary chunk"))
+        }
+        Err(e) => panic!("expected SyntaxError, got {:?}", e),
+    };
+
+    Ok(())
+}
+
 #[test]
 fn test_lua_multi() -> Result<()> {
     let lua = Lua::new();
@@ -115,6 +222,7 @@ fn test_coercion() -> Result<()> {
         int = 123
         str = "123"
         num = 123.0
+        func = function() end
     "#,
     )
     .exec()?;
@@ -123,6 +231,7 @@ fn test_coercion() -> Result<()> {
     assert_eq!(globals.get::<_, String>("int")?, "123");
     assert_eq!(globals.get::<_, i32>("str")?, 123);
     assert_eq!(globals.get::<_, i32>("num")?, 123);
+    assert!(globals.get::<_, String>("func").is_err());
 
     Ok(())
 }
@@ -266,62 +375,139 @@ fn test_error() -> Result<()> {
 
     assert!(understand_recursion.call::<_, ()>(()).is_err());
 
-    match catch_unwind(|| -> Result<()> {
-        let lua = Lua::new();
-        let globals = lua.globals();
+    Ok(())
+}
 
+#[test]
+fn test_panic() -> Result<()> {
+    fn make_lua(options: LuaOptions) -> Result<Lua> {
+        let lua = Lua::new_with(StdLib::ALL_SAFE, options)?;
+        let rust_panic_function =
+            lua.create_function(|_, msg: Option<StdString>| -> Result<()> {
+                if let Some(msg) = msg {
+                    panic!("{}", msg)
+                }
+                panic!("rust panic")
+            })?;
+        lua.globals()
+            .set("rust_panic_function", rust_panic_function)?;
+        Ok(lua)
+    }
+
+    // Test triggerting Lua error passing Rust panic (must be resumed)
+    {
+        let lua = make_lua(LuaOptions::default())?;
+
+        match catch_unwind(AssertUnwindSafe(|| -> Result<()> {
+            lua.load(
+                r#"
+                _, err = pcall(rust_panic_function)
+                error(err)
+            "#,
+            )
+            .exec()
+        })) {
+            Ok(Ok(_)) => panic!("no panic was detected"),
+            Ok(Err(e)) => panic!("error during panic test {:?}", e),
+            Err(p) => assert!(*p.downcast::<&str>().unwrap() == "rust panic"),
+        };
+
+        // Trigger same panic again
+        match lua.load("error(err)").exec() {
+            Ok(_) => panic!("no error was detected"),
+            Err(Error::PreviouslyResumedPanic) => {}
+            Err(e) => panic!("expected PreviouslyResumedPanic, got {:?}", e),
+        }
+    }
+
+    // Test returning Rust panic (must be resumed)
+    {
+        let lua = make_lua(LuaOptions::default())?;
+        match catch_unwind(AssertUnwindSafe(|| -> Result<()> {
+            let _catched_panic = lua
+                .load(
+                    r#"
+                    -- Set global
+                    _, err = pcall(rust_panic_function)
+                    return err
+                "#,
+                )
+                .eval::<Value>()?;
+            Ok(())
+        })) {
+            Ok(_) => panic!("no panic was detected"),
+            Err(_) => {}
+        };
+
+        assert!(lua.globals().get::<_, Value>("err")? == Value::Nil);
+        match lua.load("tostring(err)").exec() {
+            Ok(_) => panic!("no error was detected"),
+            Err(Error::CallbackError { ref cause, .. }) => match cause.as_ref() {
+                Error::PreviouslyResumedPanic => {}
+                e => panic!("expected PreviouslyResumedPanic, got {:?}", e),
+            },
+            Err(e) => panic!("expected CallbackError, got {:?}", e),
+        }
+    }
+
+    // Test representing rust panic as a string
+    match catch_unwind(|| -> Result<()> {
+        let lua = make_lua(LuaOptions::default())?;
         lua.load(
             r#"
-            function rust_panic()
-                local _, err = pcall(function () rust_panic_function() end)
-                if err ~= nil then
-                    error(err)
-                end
-            end
+            local _, err = pcall(rust_panic_function)
+            error(tostring(err))
         "#,
         )
-        .exec()?;
-        let rust_panic_function =
-            lua.create_function(|_, ()| -> Result<()> { panic!("test_panic") })?;
-        globals.set("rust_panic_function", rust_panic_function)?;
-
-        let rust_panic = globals.get::<_, Function>("rust_panic")?;
-
-        rust_panic.call::<_, ()>(())
-    }) {
-        Ok(Ok(_)) => panic!("no panic was detected"),
-        Ok(Err(e)) => panic!("error during panic test {:?}", e),
-        Err(p) => assert!(*p.downcast::<&str>().unwrap() == "test_panic"),
-    };
-
-    match catch_unwind(|| -> Result<()> {
-        let lua = Lua::new();
-        let globals = lua.globals();
-
-        lua.load(
-            r#"
-            function rust_panic()
-                local _, err = pcall(function () rust_panic_function() end)
-                if err ~= nil then
-                    error(tostring(err))
-                end
-            end
-        "#,
-        )
-        .exec()?;
-        let rust_panic_function =
-            lua.create_function(|_, ()| -> Result<()> { panic!("test_panic") })?;
-        globals.set("rust_panic_function", rust_panic_function)?;
-
-        let rust_panic = globals.get::<_, Function>("rust_panic")?;
-
-        rust_panic.call::<_, ()>(())
+        .exec()
     }) {
         Ok(Ok(_)) => panic!("no error was detected"),
         Ok(Err(Error::RuntimeError(_))) => {}
-        Ok(Err(e)) => panic!("unexpected error during panic test {:?}", e),
+        Ok(Err(e)) => panic!("expected RuntimeError, got {:?}", e),
         Err(_) => panic!("panic was detected"),
-    };
+    }
+
+    // Test disabling `catch_rust_panics` option / pcall correctness
+    match catch_unwind(|| -> Result<()> {
+        let lua = make_lua(LuaOptions::new().catch_rust_panics(false))?;
+        lua.load(
+            r#"
+            local ok, err = pcall(function(msg) error(msg) end, "hello")
+            assert(not ok and err:find("hello") ~= nil)
+
+            ok, err = pcall(rust_panic_function, "rust panic from lua")
+            -- Nothing to return, panic should be automatically resumed
+        "#,
+        )
+        .exec()
+    }) {
+        Ok(r) => panic!("no panic was detected: {:?}", r),
+        Err(p) => assert!(*p.downcast::<StdString>().unwrap() == "rust panic from lua"),
+    }
+
+    // Test enabling `catch_rust_panics` option / xpcall correctness
+    match catch_unwind(|| -> Result<()> {
+        let lua = make_lua(LuaOptions::new().catch_rust_panics(false))?;
+        lua.load(
+            r#"
+            local msgh_ok = false
+            local msgh = function(err)
+                msgh_ok = err ~= nil and err:find("hello") ~= nil
+                return err
+            end
+            local ok, err = xpcall(function(msg) error(msg) end, msgh, "hello")
+            assert(not ok and err:find("hello") ~= nil)
+            assert(msgh_ok)
+
+            ok, err = xpcall(rust_panic_function, msgh, "rust panic from lua")
+            -- Nothing to return, panic should be automatically resumed
+        "#,
+        )
+        .exec()
+    }) {
+        Ok(r) => panic!("no panic was detected: {:?}", r),
+        Err(p) => assert!(*p.downcast::<StdString>().unwrap() == "rust panic from lua"),
+    }
 
     Ok(())
 }
@@ -389,7 +575,7 @@ fn test_num_conversion() -> Result<()> {
 
     assert_eq!(lua.load("1.0").eval::<i64>()?, 1);
     assert_eq!(lua.load("1.0").eval::<f64>()?, 1.0);
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "lua54", feature = "lua53"))]
     assert_eq!(lua.load("1.0").eval::<String>()?, "1.0");
     #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
     assert_eq!(lua.load("1.0").eval::<String>()?, "1");
@@ -405,7 +591,9 @@ fn test_num_conversion() -> Result<()> {
     assert!(lua.load("math.huge").eval::<i64>().is_err());
 
     assert_eq!(lua.unpack::<f64>(lua.pack(f32::MAX)?)?, f32::MAX as f64);
-    assert!(lua.unpack::<f32>(lua.pack(f64::MAX)?).is_err());
+    assert_eq!(lua.unpack::<f64>(lua.pack(f32::MIN)?)?, f32::MIN as f64);
+    assert_eq!(lua.unpack::<f32>(lua.pack(f64::MAX)?)?, f32::INFINITY);
+    assert_eq!(lua.unpack::<f32>(lua.pack(f64::MIN)?)?, f32::NEG_INFINITY);
 
     assert_eq!(lua.unpack::<i128>(lua.pack(1i128 << 64)?)?, 1i128 << 64);
 
@@ -466,7 +654,12 @@ fn test_pcall_xpcall() -> Result<()> {
     assert_eq!(globals.get::<_, String>("pcall_error")?, "testerror");
 
     assert_eq!(globals.get::<_, bool>("xpcall_statusr")?, false);
-    #[cfg(any(feature = "lua53", feature = "lua52", feature = "luajit"))]
+    #[cfg(any(
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luajit"
+    ))]
     assert_eq!(
         globals.get::<_, std::string::String>("xpcall_error")?,
         "testerror"
@@ -693,6 +886,24 @@ fn too_many_binds() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_ref_stack_exhaustion() {
+    match catch_unwind(AssertUnwindSafe(|| -> Result<()> {
+        let lua = Lua::new();
+        let mut vals = Vec::new();
+        for _ in 0..1000000 {
+            vals.push(lua.create_table()?);
+        }
+        Ok(())
+    })) {
+        Ok(_) => panic!("no panic was detected"),
+        Err(p) => assert!(p
+            .downcast::<StdString>()
+            .unwrap()
+            .starts_with("cannot create a Lua reference, out of auxiliary stack space")),
+    }
+}
+
 #[test]
 fn large_args() -> Result<()> {
     let lua = Lua::new();
@@ -799,7 +1010,7 @@ fn context_thread() -> Result<()> {
         )
         .into_function()?;
 
-    #[cfg(any(feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     f.call::<_, ()>(lua.current_thread())?;
 
     #[cfg(any(feature = "lua51", feature = "luajit"))]
@@ -828,3 +1039,15 @@ fn context_thread_51() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+#[cfg(feature = "luajit")]
+fn test_jit_version() -> Result<()> {
+    let lua = Lua::new();
+    let jit: Table = lua.globals().get("jit")?;
+    assert!(jit
+        .get::<_, String>("version")?
+        .to_str()?
+        .contains("LuaJIT"));
+    Ok(())
+}

tests/thread.rs

@@ -100,7 +100,12 @@ fn coroutine_from_closure() -> Result<()> {
     let thrd_main = lua.create_function(|_, ()| Ok(()))?;
     lua.globals().set("main", thrd_main)?;
 
-    #[cfg(any(feature = "lua53", feature = "lua52", feature = "luajit"))]
+    #[cfg(any(
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luajit"
+    ))]
     let thrd: Thread = lua.load("coroutine.create(main)").eval()?;
     #[cfg(feature = "lua51")]
     let thrd: Thread = lua