v0.11.6

In Luau this function returns heap-allocated string rather than static string,
so accessing this value when Lua state is destroyed is UB.
Fixes #674

.github/workflows/main.yml

@@ -9,12 +9,12 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         rust: [stable]
-        lua: [lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
         include:
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
           - os: macos-latest
-            target: x86_64-apple-darwin
+            target: aarch64-apple-darwin
           - os: windows-latest
             target: x86_64-pc-windows-msvc
     steps:
@@ -31,35 +31,19 @@ jobs:
           cargo build --features "${{ matrix.lua }},vendored,async,serde,macros,anyhow,userdata-wrappers,send"
         shell: bash
       - name: Build ${{ matrix.lua }} pkg-config
-        if: ${{ matrix.os == 'ubuntu-latest' }}
+        if: ${{ matrix.os == 'ubuntu-latest' && matrix.lua != 'lua55' }}
         run: |
           sudo apt-get update
           sudo apt-get install -y --no-install-recommends liblua5.4-dev liblua5.3-dev liblua5.2-dev liblua5.1-0-dev libluajit-5.1-dev
           cargo build --features "${{ matrix.lua }}"
 
-  build_aarch64_cross_macos:
-    name: Cross-compile to aarch64-apple-darwin
-    runs-on: macos-latest
-    needs: build
-    strategy:
-      matrix:
-        lua: [lua54, lua53, lua52, lua51, luajit]
-    steps:
-      - uses: actions/checkout@main
-      - uses: dtolnay/rust-toolchain@stable
-        with:
-          toolchain: stable
-          target: aarch64-apple-darwin
-      - name: Cross-compile
-        run: cargo build --target aarch64-apple-darwin --features "${{ matrix.lua }},vendored,async,send,serde,macros,anyhow,userdata-wrappers"
-
   build_aarch64_cross_ubuntu:
     name: Cross-compile to aarch64-unknown-linux-gnu
     runs-on: ubuntu-latest
     needs: build
     strategy:
       matrix:
-        lua: [lua54, lua53, lua52, lua51, luajit]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit]
     steps:
       - uses: actions/checkout@main
       - uses: dtolnay/rust-toolchain@stable
@@ -81,7 +65,7 @@ jobs:
     needs: build
     strategy:
       matrix:
-        lua: [lua54, lua53, lua52, lua51]
+        lua: [lua55, lua54, lua53, lua52, lua51]
     steps:
       - uses: actions/checkout@main
       - uses: dtolnay/rust-toolchain@stable
@@ -105,12 +89,12 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         rust: [stable, nightly]
-        lua: [lua54, lua53, lua52, lua51, luajit, luajit52, luau, luau-jit, luau-vector4]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit, luajit52, luau, luau-jit, luau-vector4]
         include:
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
           - os: macos-latest
-            target: x86_64-apple-darwin
+            target: aarch64-apple-darwin
           - os: windows-latest
             target: x86_64-pc-windows-msvc
     steps:
@@ -126,8 +110,8 @@ jobs:
           cargo test --features "${{ matrix.lua }},vendored,async,serde,macros,anyhow,userdata-wrappers"
           cargo test --features "${{ matrix.lua }},vendored,async,serde,macros,anyhow,userdata-wrappers,send"
         shell: bash
-      - name: Run compile tests (macos lua54)
-        if: ${{ matrix.os == 'macos-latest' && matrix.lua == 'lua54' }}
+      - name: Run compile tests (macos lua55)
+        if: ${{ matrix.os == 'macos-latest' && matrix.lua == 'lua55' }}
         run: |
           TRYBUILD=overwrite cargo test --features "${{ matrix.lua }},vendored" --tests -- --ignored
           TRYBUILD=overwrite cargo test --features "${{ matrix.lua }},vendored,async,send,serde,macros" --tests -- --ignored
@@ -141,7 +125,7 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         rust: [nightly]
-        lua: [lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
         include:
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
@@ -168,7 +152,7 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         rust: [nightly]
-        lua: [lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
         include:
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
@@ -194,12 +178,12 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest]
         rust: [stable]
-        lua: [lua54, lua53, lua52, lua51, luajit]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit]
         include:
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
           - os: macos-latest
-            target: x86_64-apple-darwin
+            target: aarch64-apple-darwin
     steps:
       - uses: actions/checkout@main
       - uses: dtolnay/rust-toolchain@stable
@@ -240,7 +224,7 @@ jobs:
     needs: build
     strategy:
       matrix:
-        lua: [lua54, lua53, lua52, lua51, luau]
+        lua: [lua55, lua54, lua53, lua52, lua51, luau]
     steps:
       - uses: actions/checkout@main
       - uses: dtolnay/rust-toolchain@stable
@@ -256,6 +240,41 @@ jobs:
           cargo test --tests --features "${{ matrix.lua }},vendored"
           cargo test --tests --features "${{ matrix.lua }},vendored,async,serde,macros,anyhow,userdata-wrappers"
 
+  test_wasm32_wasip2:
+    name: Test on wasm32-wasip2
+    runs-on: ubuntu-latest
+    needs: build
+    strategy:
+      matrix:
+        lua: [lua55, lua54, lua53, lua52, lua51]
+    steps:
+      - uses: actions/checkout@main
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: nightly-2025-10-02
+          target: wasm32-wasip2
+      - name: Install wasi-sdk/Wasmtime
+        working-directory: ${{ runner.tool_cache }}
+        run: |
+          wasi_sdk=29
+          wasmtime=v40.0.1
+
+          curl -LO https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-$wasi_sdk/wasi-sdk-$wasi_sdk.0-x86_64-linux.tar.gz
+          tar xf wasi-sdk-$wasi_sdk.0-x86_64-linux.tar.gz
+          WASI_SDK_PATH=`pwd`/wasi-sdk-$wasi_sdk.0-x86_64-linux
+          echo "WASI_SDK_PATH=$WASI_SDK_PATH" >> $GITHUB_ENV
+          echo "CC_wasm32_wasip2=$WASI_SDK_PATH/bin/clang" >> $GITHUB_ENV
+          echo "CARGO_TARGET_WASM32_WASIP2_LINKER=$WASI_SDK_PATH/bin/clang" >> $GITHUB_ENV
+          echo "CARGO_TARGET_WASM32_WASIP2_RUSTFLAGS=-Clink-arg=-Wl,--export=cabi_realloc" >> $GITHUB_ENV
+
+          curl -LO https://github.com/bytecodealliance/wasmtime/releases/download/$wasmtime/wasmtime-$wasmtime-x86_64-linux.tar.xz
+          tar xf wasmtime-$wasmtime-x86_64-linux.tar.xz
+          echo "CARGO_TARGET_WASM32_WASIP2_RUNNER=`pwd`/wasmtime-$wasmtime-x86_64-linux/wasmtime -W exceptions" >> $GITHUB_ENV
+      - name: Run ${{ matrix.lua }} tests
+        run: |
+          cargo test --target wasm32-wasip2 --tests --features "${{ matrix.lua }},vendored"
+          cargo test --target wasm32-wasip2 --tests --features "${{ matrix.lua }},vendored,serde,macros,anyhow,userdata-wrappers"
+
   rustfmt:
     name: Rustfmt
     runs-on: ubuntu-latest
@@ -271,7 +290,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        lua: [lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
+        lua: [lua55, lua54, lua53, lua52, lua51, luajit, luau, luau-jit, luau-vector4]
     steps:
       - uses: actions/checkout@main
       - uses: dtolnay/rust-toolchain@stable

.github/workflows/typos.yml

@@ -1,17 +1,22 @@
-name: Typos Check
+name: Spelling Check
 on:
   pull_request:
   workflow_dispatch:
 
+permissions:
+  contents: read
+
+env:
+  CLICOLOR: 1
+
 jobs:
-  run:
+  spelling:
     name: Spell Check with Typos
     runs-on: ubuntu-latest
     steps:
     - name: Checkout Actions Repository
-      uses: actions/checkout@v4
-
+      uses: actions/checkout@main
     - name: Check spelling
-      uses: crate-ci/typos@master
+      uses: crate-ci/typos@v1.42.1
       with:
         config: ./typos.toml

CHANGELOG.md

@@ -1,3 +1,69 @@
+## v0.11.6 (Jan 27, 2026)
+
+- Added Lua 5.5 support (`lua55` feature flag)
+- Luau updated to 0.705+
+- Added `AnyUserData::is_proxy` method to check if userdata is a proxy
+- Added `num_params`, `num_upvalues`, `is_vararg` to `FunctionInfo`
+
+## v0.11.5 (Nov 22, 2025)
+
+- Luau updated to 0.701
+- Added `Lua::set_memory_category` and `Lua::heap_dump` functions to profile (Luau) memory
+- Added `Lua::type_metatable` helper to get metatable of a primitive type
+- Added `Lua::traceback` function to generate stack traces at different levels
+- Added `add_method_once` /`add_async_method_once` UserData methods (experimental)
+- Make `AnyUserData::type_name` public
+- impl `IntoLuaMulti` for `&MultiValue`
+- Bugfixes and async perf improvements
+
+## v0.11.4 (Sep 29, 2025)
+
+- Make `Value::to_serializable` public
+- Add new serde option `detect_mixed_tables` (to encode mixed array+map tables)
+- Add `ObjectLike::get_path` helper (for tables and userdata)
+
+## v0.11.3 (Aug 30, 2025)
+
+- Add `Lua::yield_with` to use as `coroutine.yield` functional replacement in async functions for any Lua
+- Do not try to yield at non-yielable points in Luau interrupt (#632)
+- Add `Buffer::cursor` method (Luau)
+- Add `Lua::create_buffer_with_capacity` method (Luau)
+- Make Lua reference values cheap to clone (only increments ref count)
+- Fix panic on large (>67M entries) table creation
+
+## v0.11.2 (Aug 10, 2025)
+
+- Faster stack push for `Variadic<T>`
+- Fix handling Windows paths with drive letter in Luau require (#623)
+- Make Luau registered aliases ascii case-insensitive (#620)
+- Fix deserializing negative zeros `-0.0` (#618)
+
+## v0.11.1 (Jul 15, 2025)
+
+- Fixed bug exhausting Lua auxiliary stack and leaving it without reserve (#615)
+- `Lua::push_c_function` now correctly handles OOM for Lua 5.1 and Luau
+
+## v0.11.0 (Jul 14, 2025)
+
+Changes since v0.11.0-beta.3
+
+- Allow linking external Lua libraries in a build script (e.g. pluto) using `external` mlua-sys feature flag
+- `Lua::inspect_stack` takes a callback with `&Debug` argument, instead of returning `Debug` directly
+- Added `Debug::function` method to get function running at a given level
+- `Debug::curr_line` is deprecated in favour of `Debug::current_line` that returns `Option<usize>`
+- Added `Lua::set_globals` method to replace global environment
+- `Table::set_metatable` now returns `Result<()>` (this operation can fail in sandboxed Luau mode)
+- `impl ToString` replaced with `Into<StdString>`  in `UserData` registration
+- `Value::as_str` and `Value::as_string_lossy` methods are deprecated (as they are non-idiomatic)
+- Bugfixes and improvements
+
+## v0.11.0-beta.3 (Jun 23, 2025)
+
+- Luau in sandboxed mode has reduced options in `collectgarbage` function (to follow the official doc)
+- `Function::deep_clone` now returns `Result<Function>` as this operation can trigger memory errors
+- Luau "Require" resolves included Lua files relative to the current directory (#605)
+- Fixed bug when finalizing `AsyncThread` on drop (`call_async` methods family)
+
 ## v0.11.0-beta.2 (Jun 12, 2025)
 
 - Lua 5.4 updated to 5.4.8

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "mlua"
-version = "0.11.0-beta.2" # remember to update mlua_derive
+version = "0.11.6" # remember to update mlua_derive
 authors = ["Aleksandr Orlenko <zxteam@pm.me>", "kyren <catherine@kyju.org>"]
-rust-version = "1.79.0"
+rust-version = "1.85.0"
 edition = "2021"
 repository = "https://github.com/mlua-rs/mlua"
 documentation = "https://docs.rs/mlua"
@@ -11,12 +11,12 @@ keywords = ["lua", "luajit", "luau", "async", "scripting"]
 categories = ["api-bindings", "asynchronous"]
 license = "MIT"
 description = """
-High level bindings to Lua 5.4/5.3/5.2/5.1 (including LuaJIT) and Luau
+High level bindings to Lua 5.5/5.4/5.3/5.2/5.1 (including LuaJIT) and Luau
 with async/await features and support of writing native Lua modules in Rust.
 """
 
 [package.metadata.docs.rs]
-features = ["lua54", "vendored", "async", "send", "serde", "macros"]
+features = ["lua55", "vendored", "async", "send", "serde", "macros"]
 rustdoc-args = ["--cfg", "docsrs"]
 
 [workspace]
@@ -26,6 +26,7 @@ members = [
 ]
 
 [features]
+lua55 = ["ffi/lua55"]
 lua54 = ["ffi/lua54"]
 lua53 = ["ffi/lua53"]
 lua52 = ["ffi/lua52"]
@@ -49,7 +50,7 @@ userdata-wrappers = ["parking_lot/send_guard"]
 serialize = ["serde"]
 
 [dependencies]
-mlua_derive = { version = "=0.11.0-beta.2", optional = true, path = "mlua_derive" }
+mlua_derive = { version = "=0.11.0", optional = true, path = "mlua_derive" }
 bstr = { version = "1.0", features = ["std"], default-features = false }
 either = "1.0"
 num-traits = { version = "0.2.14" }
@@ -61,25 +62,26 @@ serde-value = { version = "0.7", optional = true }
 parking_lot = { version = "0.12", features = ["arc_lock"] }
 anyhow = { version = "1.0", optional = true }
 rustversion = "1.0"
+libc = "0.2"
 
-ffi = { package = "mlua-sys", version = "0.8.0", path = "mlua-sys" }
+ffi = { package = "mlua-sys", version = "0.10.0", path = "mlua-sys" }
 
 [dev-dependencies]
 trybuild = "1.0"
-hyper = { version = "1.2", features = ["full"] }
-hyper-util = { version = "0.1.3", features = ["full"] }
-http-body-util = "0.1.1"
-reqwest = { version = "0.12", features = ["json"] }
 tokio = { version = "1.0", features = ["macros", "rt", "time"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = { version = "1.0", features = ["arbitrary_precision"] }
 maplit = "1.0"
-tempfile = "3"
 static_assertions = "1.0"
 
-[target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
-criterion = { version = "0.6", features = ["async_tokio"] }
-rustyline = "16.0"
+[target.'cfg(not(target_family = "wasm"))'.dev-dependencies]
+hyper = { version = "1.2", features = ["full"] }
+hyper-util = { version = "0.1.3", features = ["full"] }
+http-body-util = "0.1.1"
+reqwest = { version = "0.12", features = ["json"] }
+tempfile = "3"
+criterion = { version = "0.7", features = ["async_tokio"] }
+rustyline = "17.0"
 tokio = { version = "1.0", features = ["full"] }
 
 [lints.rust]

README.md

@@ -17,20 +17,14 @@
 [Benchmarks]: https://github.com/khvzak/script-bench-rs
 [FAQ]: FAQ.md
 
-# The main branch is the development version of `mlua`. Please see the [v0.10](https://github.com/mlua-rs/mlua/tree/v0.10) branch for the stable versions of `mlua`.
-
-> **Note**
->
-> See v0.10 [release notes](https://github.com/mlua-rs/mlua/blob/main/docs/release_notes/v0.10.md).
-
-`mlua` is a set of bindings to the [Lua](https://www.lua.org) programming language for Rust with a goal to provide a
+`mlua` is a set of bindings to the [Lua](https://www.lua.org) programming language for Rust with a goal of providing a
 _safe_ (as much as possible), high level, easy to use, practical and flexible API.
 
-Started as an `rlua` fork, `mlua` supports Lua 5.4, 5.3, 5.2, 5.1 (including LuaJIT) and [Luau] and allows writing native Lua modules in Rust as well as using Lua in a standalone mode.
+Started as an `rlua` fork, `mlua` supports Lua 5.5, 5.4, 5.3, 5.2, 5.1 (including LuaJIT) and [Luau] and allows writing native Lua modules in Rust as well as using Lua in a standalone mode.
 
 `mlua` is tested on Windows/macOS/Linux including module mode in [GitHub Actions] on `x86_64` platforms and cross-compilation to `aarch64` (other targets are also supported).
 
-WebAssembly (WASM) is supported through `wasm32-unknown-emscripten` target for all Lua/Luau versions excluding JIT.
+WebAssembly (WASM) is supported through the `wasm32-unknown-emscripten` target for all Lua/Luau versions excluding JIT.
 
 [GitHub Actions]: https://github.com/mlua-rs/mlua/actions
 [Luau]: https://luau.org
@@ -39,9 +33,10 @@ WebAssembly (WASM) is supported through `wasm32-unknown-emscripten` target for a
 
 ### Feature flags
 
-`mlua` uses feature flags to reduce the amount of dependencies and compiled code, and allow to choose only required set of features.
+`mlua` uses feature flags to reduce the number of dependencies and compiled code, and allow choosing only the required set of features.
 Below is a list of the available feature flags. By default `mlua` does not enable any features.
 
+* `lua55`: enable Lua [5.5] support
 * `lua54`: enable Lua [5.4] support
 * `lua53`: enable Lua [5.3] support
 * `lua52`: enable Lua [5.2] support
@@ -61,6 +56,7 @@ Below is a list of the available feature flags. By default `mlua` does not enabl
 * `anyhow`: enable `anyhow::Error` conversion into Lua
 * `userdata-wrappers`: opt into `impl UserData` for `Rc<T>`/`Arc<T>`/`Rc<RefCell<T>>`/`Arc<Mutex<T>>` where `T: UserData`
 
+[5.5]: https://www.lua.org/manual/5.5/manual.html
 [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
@@ -100,11 +96,11 @@ cargo run --example async_http_server --features=lua54,async,macros,send
 curl -v http://localhost:3000
 ```
 
-### Serialization (serde) support
+### Serde support
 
-With the `serde` 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 the [`serde::Serialize`] trait implementation for it (including `UserData` support).
+With the `serde` 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 the [`serde::Serialize`] trait implementation for `mlua::Value` (including `UserData` support).
 
-[Example](examples/serialize.rs)
+[Example](examples/serde.rs)
 
 [`serde::Serialize`]: https://docs.serde.rs/serde/ser/trait.Serialize.html
 [`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
@@ -135,7 +131,7 @@ Add to `Cargo.toml`:
 
 ``` toml
 [dependencies]
-mlua = { version = "0.10", features = ["lua54", "vendored"] }
+mlua = { version = "0.11", features = ["lua54", "vendored"] }
 ```
 
 `main.rs`
@@ -170,7 +166,7 @@ Add to `Cargo.toml`:
 crate-type = ["cdylib"]
 
 [dependencies]
-mlua = { version = "0.10", features = ["lua54", "module"] }
+mlua = { version = "0.11", features = ["lua54", "module"] }
 ```
 
 `lib.rs`:
@@ -276,7 +272,7 @@ remain usable after a user generated panic, and such panics should not break int
 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.
+Below is a list of `mlua` behaviors that should be considered bugs.
 If you encounter them, a bug report would be very welcome:
 
   + If you can cause UB with `mlua` without typing the word "unsafe", this is a bug.

benches/benchmark.rs

@@ -128,6 +128,22 @@ fn table_traversal_sequence(c: &mut Criterion) {
     });
 }
 
+fn table_ref_clone(c: &mut Criterion) {
+    let lua = Lua::new();
+
+    let t = lua.create_table().unwrap();
+
+    c.bench_function("table [ref clone]", |b| {
+        b.iter_batched(
+            || collect_gc_twice(&lua),
+            |_| {
+                let _t2 = t.clone();
+            },
+            BatchSize::SmallInput,
+        );
+    });
+}
+
 fn function_create(c: &mut Criterion) {
     let lua = Lua::new();
 
@@ -350,6 +366,42 @@ fn userdata_call_method(c: &mut Criterion) {
     });
 }
 
+// A userdata method call that goes through an implicit `__index` function
+fn userdata_call_method_complex(c: &mut Criterion) {
+    struct UserData(u64);
+    impl LuaUserData for UserData {
+        fn register(registry: &mut LuaUserDataRegistry<Self>) {
+            registry.add_field_method_get("val", |_, this| Ok(this.0));
+            registry.add_method_mut("inc_by", |_, this, by: u64| {
+                this.0 += by;
+                Ok(this.0)
+            });
+
+            #[cfg(feature = "luau")]
+            registry.enable_namecall();
+        }
+    }
+
+    let lua = Lua::new();
+    let ud = lua.create_userdata(UserData(0)).unwrap();
+    let inc_by = lua
+        .load("function(ud, s) return ud:inc_by(s) end")
+        .eval::<LuaFunction>()
+        .unwrap();
+
+    c.bench_function("userdata [call method complex]", |b| {
+        b.iter_batched(
+            || {
+                collect_gc_twice(&lua);
+            },
+            |_| {
+                inc_by.call::<()>((&ud, 1)).unwrap();
+            },
+            BatchSize::SmallInput,
+        );
+    });
+}
+
 fn userdata_async_call_method(c: &mut Criterion) {
     struct UserData(i64);
     impl LuaUserData for UserData {
@@ -399,6 +451,7 @@ criterion_group! {
         table_traversal_pairs,
         table_traversal_for_each,
         table_traversal_sequence,
+        table_ref_clone,
 
         function_create,
         function_call_sum,
@@ -413,6 +466,7 @@ criterion_group! {
         userdata_create,
         userdata_call_index,
         userdata_call_method,
+        userdata_call_method_complex,
         userdata_async_call_method,
 }
 

docs/release_notes/v0.9.md

@@ -336,7 +336,7 @@ In previous mlua versions, building a Lua module for Windows requires having Lua
 In contrast, on Linux and macOS, modules can be built without any external dependencies using the `-undefined=dynamic_lookup` linker flag.
 
 With Rust 1.71+ it's now possible to lift this restriction for Windows as well. You can build modules normally and they will be linked with
-`lua54.dll`/`lua53.dll`/`lua52.dll`/`lua51.dll` depending on the enabled Lua version.
+`lua5x.dll` depending on the enabled Lua version.
 
 You still need to have the dll although, linked to application where the module will be loaded.
 

examples/module/Cargo.toml

@@ -10,6 +10,7 @@ crate-type = ["cdylib"]
 [workspace]
 
 [features]
+lua55 = ["mlua/lua55"]
 lua54 = ["mlua/lua54"]
 lua53 = ["mlua/lua53"]
 lua52 = ["mlua/lua52"]

examples/repl.rs

@@ -20,14 +20,16 @@ fn main() {
             match lua.load(&line).eval::<MultiValue>() {
                 Ok(values) => {
                     editor.add_history_entry(line).unwrap();
-                    println!(
-                        "{}",
-                        values
-                            .iter()
-                            .map(|value| format!("{:#?}", value))
-                            .collect::<Vec<_>>()
-                            .join("\t")
-                    );
+                    if values.len() > 0 {
+                        println!(
+                            "{}",
+                            values
+                                .iter()
+                                .map(|value| format!("{:#?}", value))
+                                .collect::<Vec<_>>()
+                                .join("\t")
+                        );
+                    }
                     break;
                 }
                 Err(Error::SyntaxError {

mlua-sys/Cargo.toml

@@ -1,9 +1,9 @@
 [package]
 name = "mlua-sys"
-version = "0.8.0"
+version = "0.10.0"
 authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
-rust-version = "1.71"
-edition = "2021"
+rust-version = "1.85"
+edition = "2024"
 repository = "https://github.com/mlua-rs/mlua"
 documentation = "https://docs.rs/mlua-sys"
 readme = "README.md"
@@ -12,14 +12,15 @@ license = "MIT"
 links = "lua"
 build = "build/main.rs"
 description = """
-Low level (FFI) bindings to Lua 5.4/5.3/5.2/5.1 (including LuaJIT) and Luau
+Low level (FFI) bindings to Lua 5.5/5.4/5.3/5.2/5.1 (including LuaJIT) and Luau
 """
 
 [package.metadata.docs.rs]
-features = ["lua54", "vendored"]
+features = ["lua55", "vendored"]
 rustdoc-args = ["--cfg", "docsrs"]
 
 [features]
+lua55 = []
 lua54 = []
 lua53 = []
 lua52 = []
@@ -30,17 +31,19 @@ luau = ["luau0-src"]
 luau-codegen = ["luau"]
 luau-vector4 = ["luau"]
 vendored = ["lua-src", "luajit-src"]
+external = []
 module = []
 
 [dependencies]
+libc = "0.2"
 
 [build-dependencies]
 cc = "1.0"
 cfg-if = "1.0"
 pkg-config = "0.3.17"
-lua-src = { version = ">= 548.1.0, < 548.2.0", optional = true }
+lua-src = { version = ">= 550.0.0, < 550.1.0", optional = true }
 luajit-src = { version = ">= 210.6.0, < 210.7.0", optional = true }
-luau0-src = { version = "0.15.0", optional = true }
+luau0-src = { version = "0.18.0", optional = true }
 
 [lints.rust]
 unexpected_cfgs = { level = "allow", check-cfg = ['cfg(raw_dylib)'] }

mlua-sys/README.md

@@ -1,8 +1,9 @@
 # mlua-sys
 
-Low level (FFI) bindings to Lua 5.4/5.3/5.2/5.1 (including LuaJIT) and [Luau].
+Low level (FFI) bindings to Lua 5.5/5.4/5.3/5.2/5.1 (including [LuaJIT]) and [Luau].
 
 Intended to be consumed by the [mlua] crate.
 
+[LuaJIT]: https://github.com/LuaJIT/LuaJIT
 [Luau]: https://github.com/luau-lang/luau
 [mlua]: https://crates.io/crates/mlua

mlua-sys/build/find_normal.rs

@@ -31,18 +31,16 @@ pub fn probe_lua() {
 
     // Find using `pkg-config`
 
+    #[cfg(feature = "lua55")]
+    let (incl_bound, excl_bound, alt_probe, ver) = ("5.5", "5.6", ["lua5.5", "lua-5.5", "lua55"], "5.5");
     #[cfg(feature = "lua54")]
-    let (incl_bound, excl_bound, alt_probe, ver) =
-        ("5.4", "5.5", ["lua5.4", "lua-5.4", "lua54"], "5.4");
+    let (incl_bound, excl_bound, alt_probe, ver) = ("5.4", "5.5", ["lua5.4", "lua-5.4", "lua54"], "5.4");
     #[cfg(feature = "lua53")]
-    let (incl_bound, excl_bound, alt_probe, ver) =
-        ("5.3", "5.4", ["lua5.3", "lua-5.3", "lua53"], "5.3");
+    let (incl_bound, excl_bound, alt_probe, ver) = ("5.3", "5.4", ["lua5.3", "lua-5.3", "lua53"], "5.3");
     #[cfg(feature = "lua52")]
-    let (incl_bound, excl_bound, alt_probe, ver) =
-        ("5.2", "5.3", ["lua5.2", "lua-5.2", "lua52"], "5.2");
+    let (incl_bound, excl_bound, alt_probe, ver) = ("5.2", "5.3", ["lua5.2", "lua-5.2", "lua52"], "5.2");
     #[cfg(feature = "lua51")]
-    let (incl_bound, excl_bound, alt_probe, ver) =
-        ("5.1", "5.2", ["lua5.1", "lua-5.1", "lua51"], "5.1");
+    let (incl_bound, excl_bound, alt_probe, ver) = ("5.1", "5.2", ["lua5.1", "lua-5.1", "lua51"], "5.1");
     #[cfg(feature = "luajit")]
     let (incl_bound, excl_bound, alt_probe, ver) = ("2.0.4", "2.2", [], "JIT");
 
@@ -54,9 +52,7 @@ pub fn probe_lua() {
 
     if lua.is_err() {
         for pkg in alt_probe {
-            lua = pkg_config::Config::new()
-                .cargo_metadata(true)
-                .probe(pkg);
+            lua = pkg_config::Config::new().cargo_metadata(true).probe(pkg);
 
             if lua.is_ok() {
                 break;

mlua-sys/build/find_vendored.rs

@@ -1,6 +1,9 @@
 #![allow(dead_code)]
 
 pub fn probe_lua() {
+    #[cfg(feature = "lua55")]
+    let artifacts = lua_src::Build::new().build(lua_src::Lua55);
+
     #[cfg(feature = "lua54")]
     let artifacts = lua_src::Build::new().build(lua_src::Lua54);
 

mlua-sys/build/main.rs

@@ -1,19 +1,21 @@
 cfg_if::cfg_if! {
-    if #[cfg(all(feature = "lua54", not(any(feature = "lua53", feature = "lua52", feature = "lua51", feature = "luajit", feature = "luau"))))] {
+    if #[cfg(all(feature = "lua55", not(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "lua51", feature = "luajit", feature = "luau"))))] {
         include!("main_inner.rs");
-    } else if #[cfg(all(feature = "lua53", not(any(feature = "lua54", feature = "lua52", feature = "lua51", feature = "luajit", feature = "luau"))))] {
+    } else if #[cfg(all(feature = "lua54", not(any(feature = "lua55", feature = "lua53", feature = "lua52", feature = "lua51", feature = "luajit", feature = "luau"))))] {
         include!("main_inner.rs");
-    } else if #[cfg(all(feature = "lua52", not(any(feature = "lua54", feature = "lua53", feature = "lua51", feature = "luajit", feature = "luau"))))] {
+    } else if #[cfg(all(feature = "lua53", not(any(feature = "lua55", feature = "lua54", feature = "lua52", feature = "lua51", feature = "luajit", feature = "luau"))))] {
         include!("main_inner.rs");
-    } else if #[cfg(all(feature = "lua51", not(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luajit", feature = "luau"))))] {
+    } else if #[cfg(all(feature = "lua52", not(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua51", feature = "luajit", feature = "luau"))))] {
         include!("main_inner.rs");
-    } else if #[cfg(all(feature = "luajit", not(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "lua51", feature = "luau"))))] {
+    } else if #[cfg(all(feature = "lua51", not(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52", feature = "luajit", feature = "luau"))))] {
         include!("main_inner.rs");
-    } else if #[cfg(all(feature = "luau", not(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "lua51", feature = "luajit"))))] {
+    } else if #[cfg(all(feature = "luajit", not(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52", feature = "lua51", feature = "luau"))))] {
+        include!("main_inner.rs");
+    } else if #[cfg(all(feature = "luau", not(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52", feature = "lua51", feature = "luajit"))))] {
         include!("main_inner.rs");
     } else {
         fn main() {
-            compile_error!("You can enable only one of the features: lua54, lua53, lua52, lua51, luajit, luajit52, luau");
+            compile_error!("You can enable only one of the features: lua55, lua54, lua53, lua52, lua51, luajit, luajit52, luau");
         }
     }
 }

mlua-sys/build/main_inner.rs

@@ -14,22 +14,29 @@ fn main() {
     #[cfg(all(feature = "luau", feature = "module", windows))]
     compile_error!("Luau does not support `module` mode on Windows");
 
-    #[cfg(all(feature = "module", feature = "vendored"))]
-    compile_error!("`vendored` and `module` features are mutually exclusive");
+    #[cfg(any(
+        all(feature = "vendored", any(feature = "external", feature = "module")),
+        all(feature = "external", any(feature = "vendored", feature = "module")),
+        all(feature = "module", any(feature = "vendored", feature = "external"))
+    ))]
+    compile_error!("`vendored`, `external` and `module` features are mutually exclusive");
 
     println!("cargo:rerun-if-changed=build");
 
-    let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
-    if target_os == "windows" && cfg!(feature = "module") {
-        if !std::env::var("LUA_LIB_NAME").unwrap_or_default().is_empty() {
-            // Don't use raw-dylib linking
-            find::probe_lua();
-            return;
+    // Check if compilation and linking is handled by external crate
+    if cfg!(not(feature = "external")) {
+        let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
+        if target_os == "windows" && cfg!(feature = "module") {
+            if !std::env::var("LUA_LIB_NAME").unwrap_or_default().is_empty() {
+                // Don't use raw-dylib linking
+                find::probe_lua();
+                return;
+            }
+
+            println!("cargo:rustc-cfg=raw_dylib");
         }
 
-        println!("cargo:rustc-cfg=raw_dylib");
+        #[cfg(not(feature = "module"))]
+        find::probe_lua();
     }
-
-    #[cfg(not(feature = "module"))]
-    find::probe_lua();
 }

mlua-sys/src/lib.rs

@@ -1,4 +1,4 @@
-//! Low level bindings to Lua 5.4/5.3/5.2/5.1 (including LuaJIT) and Luau.
+//! Low level bindings to Lua 5.5/5.4/5.3/5.2/5.1 (including LuaJIT) and Luau.
 
 #![allow(non_camel_case_types, non_snake_case)]
 #![allow(clippy::missing_safety_doc)]
@@ -8,6 +8,9 @@
 
 use std::os::raw::c_int;
 
+#[cfg(any(feature = "lua55", doc))]
+pub use lua55::*;
+
 #[cfg(any(feature = "lua54", doc))]
 pub use lua54::*;
 
@@ -23,7 +26,7 @@ pub use lua51::*;
 #[cfg(any(feature = "luau", doc))]
 pub use luau::*;
 
-#[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+#[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
 #[doc(hidden)]
 pub const LUA_MAX_UPVALUES: c_int = 255;
 
@@ -40,14 +43,22 @@ pub const LUA_MAX_UPVALUES: c_int = 200;
 #[doc(hidden)]
 pub const LUA_TRACEBACK_STACK: c_int = 11;
 
-// Copied from https://github.com/rust-lang/rust/blob/master/library/std/src/sys/pal/common/alloc.rs
-// The minimum alignment guaranteed by the architecture. This value is used to
-// add fast paths for low alignment values.
-#[cfg(any(
+// The minimum alignment guaranteed by the architecture.
+// Copied from https://github.com/rust-lang/rust/blob/main/library/std/src/sys/alloc/mod.rs
+#[doc(hidden)]
+#[rustfmt::skip]
+pub const SYS_MIN_ALIGN: usize = if cfg!(any(
+    all(target_arch = "riscv32", any(target_os = "espidf", target_os = "zkvm")),
+    all(target_arch = "xtensa", target_os = "espidf"),
+)) {
+    // The allocator on the esp-idf and zkvm platforms guarantees 4 byte alignment.
+    4
+} else if cfg!(any(
     target_arch = "x86",
     target_arch = "arm",
     target_arch = "m68k",
     target_arch = "csky",
+    target_arch = "loongarch32",
     target_arch = "mips",
     target_arch = "mips32r6",
     target_arch = "powerpc",
@@ -55,12 +66,11 @@ pub const LUA_TRACEBACK_STACK: c_int = 11;
     target_arch = "sparc",
     target_arch = "wasm32",
     target_arch = "hexagon",
-    all(target_arch = "riscv32", not(any(target_os = "espidf", target_os = "zkvm"))),
-    all(target_arch = "xtensa", not(target_os = "espidf")),
-))]
-#[doc(hidden)]
-pub const SYS_MIN_ALIGN: usize = 8;
-#[cfg(any(
+    target_arch = "riscv32",
+    target_arch = "xtensa",
+)) {
+    8
+} else if cfg!(any(
     target_arch = "x86_64",
     target_arch = "aarch64",
     target_arch = "arm64ec",
@@ -71,20 +81,19 @@ pub const SYS_MIN_ALIGN: usize = 8;
     target_arch = "sparc64",
     target_arch = "riscv64",
     target_arch = "wasm64",
-))]
-#[doc(hidden)]
-pub const SYS_MIN_ALIGN: usize = 16;
-// The allocator on the esp-idf and zkvm platforms guarantee 4 byte alignment.
-#[cfg(any(
-    all(target_arch = "riscv32", any(target_os = "espidf", target_os = "zkvm")),
-    all(target_arch = "xtensa", target_os = "espidf"),
-))]
-#[doc(hidden)]
-pub const SYS_MIN_ALIGN: usize = 4;
+)) {
+    16
+} else {
+    panic!("no value for SYS_MIN_ALIGN")
+};
 
 #[macro_use]
 mod macros;
 
+#[cfg(any(feature = "lua55", doc))]
+#[cfg_attr(docsrs, doc(cfg(feature = "lua55")))]
+pub mod lua55;
+
 #[cfg(any(feature = "lua54", doc))]
 #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
 pub mod lua54;

mlua-sys/src/lua51/compat.rs

@@ -2,6 +2,7 @@
 //!
 //! Based on github.com/keplerproject/lua-compat-5.3
 
+use std::ffi::CStr;
 use std::os::raw::{c_char, c_int, c_void};
 use std::{mem, ptr};
 
@@ -20,8 +21,8 @@ unsafe fn compat53_reverse(L: *mut lua_State, mut a: c_int, mut b: c_int) {
     }
 }
 
-const COMPAT53_LEVELS1: c_int = 12; // size of the first part of the stack
-const COMPAT53_LEVELS2: c_int = 10; // size of the second part of the stack
+const COMPAT53_LEVELS1: c_int = 10; // size of the first part of the stack
+const COMPAT53_LEVELS2: c_int = 11; // size of the second part of the stack
 
 unsafe fn compat53_countlevels(L: *mut lua_State) -> c_int {
     let mut ar: lua_Debug = mem::zeroed();
@@ -54,11 +55,7 @@ unsafe fn compat53_checkmode(
         while *st != 0 && *st != c {
             st = st.offset(1);
         }
-        if *st == c {
-            st
-        } else {
-            ptr::null()
-        }
+        if *st == c { st } else { ptr::null() }
     }
 
     if !mode.is_null() && strchr(mode, *modename).is_null() {
@@ -88,11 +85,10 @@ unsafe fn compat53_findfield(L: *mut lua_State, objidx: c_int, level: c_int) ->
                 lua_pop(L, 1); // remove value (but keep name)
                 return 1;
             } else if compat53_findfield(L, objidx, level - 1) != 0 {
-                // try recursively
-                lua_remove(L, -2); // remove table (but keep name)
-                lua_pushliteral(L, c".");
-                lua_insert(L, -2); // place '.' between the two names
-                lua_concat(L, 3);
+                // stack: lib_name, lib_table, field_name (top)
+                lua_pushliteral(L, c"."); // place '.' between the two names
+                lua_replace(L, -3); // (in the slot occupied by table)
+                lua_concat(L, 3); // lib_name.field_name
                 return 1;
             }
         }
@@ -101,13 +97,20 @@ unsafe fn compat53_findfield(L: *mut lua_State, objidx: c_int, level: c_int) ->
     0 // not found
 }
 
-unsafe fn compat53_pushglobalfuncname(L: *mut lua_State, ar: *mut lua_Debug) -> c_int {
+unsafe fn compat53_pushglobalfuncname(L: *mut lua_State, L1: *mut lua_State, ar: *mut lua_Debug) -> c_int {
     let top = lua_gettop(L);
-    lua_getinfo(L, cstr!("f"), ar); // push function
+    lua_getinfo(L1, cstr!("f"), ar); // push function
+    lua_xmove(L1, L, 1); // and move onto L
     lua_pushvalue(L, LUA_GLOBALSINDEX);
+    luaL_checkstack(L, 6, cstr!("not enough stack")); // slots for 'findfield'
     if compat53_findfield(L, top + 1, 2) != 0 {
+        let name = lua_tostring(L, -1);
+        if CStr::from_ptr(name).to_bytes().starts_with(b"_G.") {
+            lua_pushstring(L, name.add(3)); // push name without prefix
+            lua_remove(L, -2); // remove original name
+        }
         lua_copy(L, -1, top + 1); // move name to proper place
-        lua_pop(L, 2); // remove pushed values
+        lua_settop(L, top + 1); // remove pushed values
         1
     } else {
         lua_settop(L, top); // remove function and global table
@@ -115,27 +118,23 @@ unsafe fn compat53_pushglobalfuncname(L: *mut lua_State, ar: *mut lua_Debug) ->
     }
 }
 
-unsafe fn compat53_pushfuncname(L: *mut lua_State, ar: *mut lua_Debug) {
-    if *(*ar).namewhat != b'\0' as c_char {
-        // is there a name?
-        lua_pushfstring(L, cstr!("function '%s'"), (*ar).name);
+unsafe fn compat53_pushfuncname(L: *mut lua_State, L1: *mut lua_State, ar: *mut lua_Debug) {
+    // try first a global name
+    if compat53_pushglobalfuncname(L, L1, ar) != 0 {
+        lua_pushfstring(L, cstr!("function '%s'"), lua_tostring(L, -1));
+        lua_remove(L, -2); // remove name
+    } else if *(*ar).namewhat != b'\0' as c_char {
+        // use name from code
+        lua_pushfstring(L, cstr!("%s '%s'"), (*ar).namewhat, (*ar).name);
     } else if *(*ar).what == b'm' as c_char {
         // main?
         lua_pushliteral(L, c"main chunk");
-    } else if *(*ar).what == b'C' as c_char {
-        if compat53_pushglobalfuncname(L, ar) != 0 {
-            lua_pushfstring(L, cstr!("function '%s'"), lua_tostring(L, -1));
-            lua_remove(L, -2); // remove name
-        } else {
-            lua_pushliteral(L, c"?");
-        }
+    } else if *(*ar).what != b'C' as c_char {
+        // for Lua functions, use <file:line>
+        let short_src = (*ar).short_src.as_ptr();
+        lua_pushfstring(L, cstr!("function <%s:%d>"), short_src, (*ar).linedefined);
     } else {
-        lua_pushfstring(
-            L,
-            cstr!("function <%s:%d>"),
-            (*ar).short_src.as_ptr(),
-            (*ar).linedefined,
-        );
+        lua_pushliteral(L, c"?");
     }
 }
 
@@ -186,7 +185,8 @@ pub unsafe fn lua_isinteger(L: *mut lua_State, idx: c_int) -> c_int {
     if lua_type(L, idx) == LUA_TNUMBER {
         let n = lua_tonumber(L, idx);
         let i = lua_tointeger(L, idx);
-        if (n - i as lua_Number).abs() < lua_Number::EPSILON {
+        // Lua 5.3+ returns "false" for `-0.0`
+        if n.to_bits() == (i as lua_Number).to_bits() {
             return 1;
         }
     }
@@ -458,32 +458,36 @@ pub unsafe fn luaL_traceback(L: *mut lua_State, L1: *mut lua_State, msg: *const
     let mut ar: lua_Debug = mem::zeroed();
     let top = lua_gettop(L);
     let numlevels = compat53_countlevels(L1);
-    let mark = if numlevels > COMPAT53_LEVELS1 + COMPAT53_LEVELS2 {
-        COMPAT53_LEVELS1
-    } else {
-        0
-    };
+    #[rustfmt::skip]
+    let mut limit = if numlevels - level > COMPAT53_LEVELS1 + COMPAT53_LEVELS2 { COMPAT53_LEVELS1 } else { -1 };
 
     if !msg.is_null() {
         lua_pushfstring(L, cstr!("%s\n"), msg);
     }
     lua_pushliteral(L, c"stack traceback:");
     while lua_getstack(L1, level, &mut ar) != 0 {
-        level += 1;
-        if level == mark {
+        if limit == 0 {
             // too many levels?
-            lua_pushliteral(L, c"\n\t..."); // add a '...'
-            level = numlevels - COMPAT53_LEVELS2; // and skip to last ones
+            let n = numlevels - level - COMPAT53_LEVELS2;
+            // add warning about skip ("n + 1" because we skip current level too)
+            lua_pushfstring(L, cstr!("\n\t...\t(skipping %d levels)"), n + 1); // add warning about skip
+            level += n; // and skip to last levels
         } else {
-            lua_getinfo(L1, cstr!("Slnt"), &mut ar);
-            lua_pushfstring(L, cstr!("\n\t%s:"), ar.short_src.as_ptr());
-            if ar.currentline > 0 {
-                lua_pushfstring(L, cstr!("%d:"), ar.currentline);
+            lua_getinfo(L1, cstr!("Sln"), &mut ar);
+            if *ar.what != b't' as c_char {
+                if ar.currentline <= 0 {
+                    lua_pushfstring(L, cstr!("\n\t%s: in "), ar.short_src.as_ptr());
+                } else {
+                    lua_pushfstring(L, cstr!("\n\t%s:%d: in "), ar.short_src.as_ptr(), ar.currentline);
+                }
+                compat53_pushfuncname(L, L1, &mut ar);
+                lua_concat(L, lua_gettop(L) - top);
+            } else {
+                lua_pushstring(L, cstr!("\n\t(...tail calls...)"));
             }
-            lua_pushliteral(L, c" in ");
-            compat53_pushfuncname(L, &mut ar);
-            lua_concat(L, lua_gettop(L) - top);
         }
+        level += 1;
+        limit -= 1;
     }
     lua_concat(L, lua_gettop(L) - top);
 }

mlua-sys/src/lua51/lauxlib.rs

@@ -107,8 +107,6 @@ pub unsafe fn luaL_optstring(L: *mut lua_State, n: c_int, d: *const c_char) -> *
     luaL_optlstring(L, n, d, ptr::null_mut())
 }
 
-// Deprecated from 5.3: luaL_checkint, luaL_optint, luaL_checklong, luaL_optlong
-
 #[inline(always)]
 pub unsafe fn luaL_typename(L: *mut lua_State, i: c_int) -> *const c_char {
     lua::lua_typename(L, lua::lua_type(L, i))
@@ -138,8 +136,62 @@ pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) {
     lua::lua_getfield_(L, lua::LUA_REGISTRYINDEX, n);
 }
 
-// TODO: luaL_opt
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
 
 //
-// TODO: Generic Buffer Manipulation
+// Generic Buffer Manipulation
 //
+
+#[cfg(target_arch = "wasm32")]
+const BUFSIZ: usize = 1024; // WASI libc's BUFSIZ is 1024
+#[cfg(not(target_arch = "wasm32"))]
+const BUFSIZ: usize = libc::BUFSIZ as usize;
+
+// The buffer size used by the lauxlib buffer system.
+// The "16384" workaround is taken from the LuaJIT source code.
+pub const LUAL_BUFFERSIZE: usize = if BUFSIZ > 16384 { 8192 } else { BUFSIZ };
+
+#[repr(C)]
+pub struct luaL_Buffer {
+    pub p: *mut c_char, // current position in buffer
+    pub lvl: c_int,     // number of strings in the stack
+    pub L: *mut lua_State,
+    pub buffer: [c_char; LUAL_BUFFERSIZE],
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua51", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Buffer);
+    pub fn luaL_prepbuffer(B: *mut luaL_Buffer) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Buffer, s: *const c_char, l: usize);
+    pub fn luaL_addstring(B: *mut luaL_Buffer, s: *const c_char);
+    pub fn luaL_addvalue(B: *mut luaL_Buffer);
+    pub fn luaL_pushresult(B: *mut luaL_Buffer);
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addchar(B: *mut luaL_Buffer, c: c_char) {
+    let buffer_end = (*B).buffer.as_mut_ptr().add(LUAL_BUFFERSIZE);
+    if (*B).p >= buffer_end {
+        luaL_prepbuffer(B);
+    }
+    *(*B).p = c;
+    (*B).p = (*B).p.add(1);
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addsize(B: *mut luaL_Buffer, n: usize) {
+    (*B).p = (*B).p.add(n);
+}

mlua-sys/src/lua51/lua.rs

@@ -270,7 +270,10 @@ pub unsafe fn lua_pushcfunction(L: *mut lua_State, f: lua_CFunction) {
     lua_pushcclosure(L, f, 0)
 }
 
-// TODO: lua_strlen
+#[inline(always)]
+pub unsafe fn lua_strlen(L: *mut lua_State, i: c_int) -> usize {
+    lua_objlen(L, i)
+}
 
 #[inline(always)]
 pub unsafe fn lua_isfunction(L: *mut lua_State, n: c_int) -> c_int {

mlua-sys/src/lua52/compat.rs

@@ -51,7 +51,8 @@ pub unsafe fn lua_isinteger(L: *mut lua_State, idx: c_int) -> c_int {
     if lua_type(L, idx) == LUA_TNUMBER {
         let n = lua_tonumber(L, idx);
         let i = lua_tointeger(L, idx);
-        if (n - i as lua_Number).abs() < lua_Number::EPSILON {
+        // Lua 5.3+ returns "false" for `-0.0`
+        if n.to_bits() == (i as lua_Number).to_bits() {
             return 1;
         }
     }
@@ -124,7 +125,7 @@ pub unsafe fn lua_rawget(L: *mut lua_State, idx: c_int) -> c_int {
 
 #[inline(always)]
 pub unsafe fn lua_rawgeti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_int {
-    let n = n.try_into().expect("cannot convert index to lua_Integer");
+    let n = n.try_into().expect("cannot convert index to c_int");
     lua_rawgeti_(L, idx, n);
     lua_type(L, -1)
 }
@@ -152,7 +153,7 @@ pub unsafe fn lua_seti(L: *mut lua_State, mut idx: c_int, n: lua_Integer) {
 
 #[inline(always)]
 pub unsafe fn lua_rawseti(L: *mut lua_State, idx: c_int, n: lua_Integer) {
-    let n = n.try_into().expect("cannot convert index from lua_Integer");
+    let n = n.try_into().expect("cannot convert index to c_int");
     lua_rawseti_(L, idx, n)
 }
 

mlua-sys/src/lua52/lauxlib.rs

@@ -32,7 +32,7 @@ unsafe extern "C-unwind" {
     pub fn luaL_argerror(L: *mut lua_State, arg: c_int, extramsg: *const c_char) -> c_int;
     pub fn luaL_checklstring(L: *mut lua_State, arg: c_int, l: *mut usize) -> *const c_char;
     pub fn luaL_optlstring(L: *mut lua_State, arg: c_int, def: *const c_char, l: *mut usize)
-        -> *const c_char;
+    -> *const c_char;
     pub fn luaL_checknumber(L: *mut lua_State, arg: c_int) -> lua_Number;
     pub fn luaL_optnumber(L: *mut lua_State, arg: c_int, def: lua_Number) -> lua_Number;
     pub fn luaL_checkinteger(L: *mut lua_State, arg: c_int) -> lua_Integer;
@@ -166,13 +166,76 @@ pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) {
     lua::lua_getfield_(L, lua::LUA_REGISTRYINDEX, n);
 }
 
-// luaL_opt would be implemented here but it is undocumented, so it's omitted
-
 #[inline(always)]
 pub unsafe fn luaL_loadbuffer(L: *mut lua_State, s: *const c_char, sz: usize, n: *const c_char) -> c_int {
     luaL_loadbufferx(L, s, sz, n, ptr::null())
 }
 
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
+
 //
-// TODO: Generic Buffer Manipulation
+// Generic Buffer Manipulation
 //
+
+#[cfg(target_arch = "wasm32")]
+const BUFSIZ: usize = 1024; // WASI libc's BUFSIZ is 1024
+#[cfg(not(target_arch = "wasm32"))]
+const BUFSIZ: usize = libc::BUFSIZ as usize;
+
+// The buffer size used by the lauxlib buffer system.
+// The "16384" workaround is taken from the LuaJIT source code.
+pub const LUAL_BUFFERSIZE: usize = if BUFSIZ > 16384 { 8192 } else { BUFSIZ };
+
+#[repr(C)]
+pub struct luaL_Buffer {
+    pub b: *mut c_char, // buffer address
+    pub size: usize,    // buffer size
+    pub n: usize,       // number of characters in buffer
+    pub L: *mut lua_State,
+    pub initb: [c_char; LUAL_BUFFERSIZE], // initial buffer space
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua52", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Buffer);
+    pub fn luaL_prepbuffsize(B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Buffer, s: *const c_char, l: usize);
+    pub fn luaL_addstring(B: *mut luaL_Buffer, s: *const c_char);
+    pub fn luaL_addvalue(B: *mut luaL_Buffer);
+    pub fn luaL_pushresult(B: *mut luaL_Buffer);
+    pub fn luaL_pushresultsize(B: *mut luaL_Buffer, sz: usize);
+    pub fn luaL_buffinitsize(L: *mut lua_State, B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+}
+
+// Macro implementations as inline functions
+
+#[inline(always)]
+pub unsafe fn luaL_prepbuffer(B: *mut luaL_Buffer) -> *mut c_char {
+    luaL_prepbuffsize(B, LUAL_BUFFERSIZE)
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addchar(B: *mut luaL_Buffer, c: c_char) {
+    if (*B).n >= (*B).size {
+        luaL_prepbuffsize(B, 1);
+    }
+    *(*B).b.add((*B).n) = c;
+    (*B).n += 1;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addsize(B: *mut luaL_Buffer, n: usize) {
+    (*B).n += n;
+}

mlua-sys/src/lua53/lauxlib.rs

@@ -1,7 +1,7 @@
 //! Contains definitions from `lauxlib.h`.
 
 use std::os::raw::{c_char, c_int, c_void};
-use std::ptr;
+use std::{mem, ptr};
 
 use super::lua::{self, lua_CFunction, lua_Integer, lua_Number, lua_State};
 
@@ -31,7 +31,7 @@ unsafe extern "C-unwind" {
     pub fn luaL_argerror(L: *mut lua_State, arg: c_int, extramsg: *const c_char) -> c_int;
     pub fn luaL_checklstring(L: *mut lua_State, arg: c_int, l: *mut usize) -> *const c_char;
     pub fn luaL_optlstring(L: *mut lua_State, arg: c_int, def: *const c_char, l: *mut usize)
-        -> *const c_char;
+    -> *const c_char;
     pub fn luaL_checknumber(L: *mut lua_State, arg: c_int) -> lua_Number;
     pub fn luaL_optnumber(L: *mut lua_State, arg: c_int, def: lua_Number) -> lua_Number;
     pub fn luaL_checkinteger(L: *mut lua_State, arg: c_int) -> lua_Integer;
@@ -166,13 +166,72 @@ pub unsafe fn luaL_tolstring(L: *mut lua_State, idx: c_int, len: *mut usize) ->
     luaL_tolstring_(L, lua::lua_absindex(L, idx), len)
 }
 
-// luaL_opt would be implemented here but it is undocumented, so it's omitted
-
 #[inline(always)]
 pub unsafe fn luaL_loadbuffer(L: *mut lua_State, s: *const c_char, sz: usize, n: *const c_char) -> c_int {
     luaL_loadbufferx(L, s, sz, n, ptr::null())
 }
 
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
+
 //
-// TODO: Generic Buffer Manipulation
+// Generic Buffer Manipulation
 //
+
+// The buffer size used by the lauxlib buffer system.
+// In Lua 5.3: LUAL_BUFFERSIZE = (int)(0x80 * sizeof(void*) * sizeof(lua_Integer))
+#[rustfmt::skip]
+pub const LUAL_BUFFERSIZE: usize = 0x80 * mem::size_of::<*const ()>() * mem::size_of::<lua_Integer>();
+
+#[repr(C)]
+pub struct luaL_Buffer {
+    pub b: *mut c_char, // buffer address
+    pub size: usize,    // buffer size
+    pub n: usize,       // number of characters in buffer
+    pub L: *mut lua_State,
+    pub initb: [c_char; LUAL_BUFFERSIZE], // initial buffer space
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua53", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Buffer);
+    pub fn luaL_prepbuffsize(B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Buffer, s: *const c_char, l: usize);
+    pub fn luaL_addstring(B: *mut luaL_Buffer, s: *const c_char);
+    pub fn luaL_addvalue(B: *mut luaL_Buffer);
+    pub fn luaL_pushresult(B: *mut luaL_Buffer);
+    pub fn luaL_pushresultsize(B: *mut luaL_Buffer, sz: usize);
+    pub fn luaL_buffinitsize(L: *mut lua_State, B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+}
+
+// Macro implementations as inline functions
+
+#[inline(always)]
+pub unsafe fn luaL_prepbuffer(B: *mut luaL_Buffer) -> *mut c_char {
+    luaL_prepbuffsize(B, LUAL_BUFFERSIZE)
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addchar(B: *mut luaL_Buffer, c: c_char) {
+    if (*B).n >= (*B).size {
+        luaL_prepbuffsize(B, 1);
+    }
+    *(*B).b.add((*B).n) = c;
+    (*B).n += 1;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addsize(B: *mut luaL_Buffer, n: usize) {
+    (*B).n += n;
+}

mlua-sys/src/lua54/lauxlib.rs

@@ -1,7 +1,7 @@
 //! Contains definitions from `lauxlib.h`.
 
-use std::os::raw::{c_char, c_int, c_void};
-use std::ptr;
+use std::os::raw::{c_char, c_double, c_int, c_long, c_void};
+use std::{mem, ptr};
 
 use super::lua::{self, lua_CFunction, lua_Integer, lua_Number, lua_State};
 
@@ -30,7 +30,7 @@ unsafe extern "C-unwind" {
     pub fn luaL_argerror(L: *mut lua_State, arg: c_int, extramsg: *const c_char) -> c_int;
     pub fn luaL_checklstring(L: *mut lua_State, arg: c_int, l: *mut usize) -> *const c_char;
     pub fn luaL_optlstring(L: *mut lua_State, arg: c_int, def: *const c_char, l: *mut usize)
-        -> *const c_char;
+    -> *const c_char;
     pub fn luaL_checknumber(L: *mut lua_State, arg: c_int) -> lua_Number;
     pub fn luaL_optnumber(L: *mut lua_State, arg: c_int, def: lua_Number) -> lua_Number;
     pub fn luaL_checkinteger(L: *mut lua_State, arg: c_int) -> lua_Integer;
@@ -91,7 +91,7 @@ unsafe extern "C-unwind" {
 
     pub fn luaL_len(L: *mut lua_State, idx: c_int) -> lua_Integer;
 
-    // TODO: luaL_addgsub
+    pub fn luaL_addgsub(B: *mut luaL_Buffer, s: *const c_char, p: *const c_char, r: *const c_char);
 
     pub fn luaL_gsub(
         L: *mut lua_State,
@@ -162,8 +162,6 @@ pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) {
     lua::lua_getfield(L, lua::LUA_REGISTRYINDEX, n);
 }
 
-// luaL_opt would be implemented here but it is undocumented, so it's omitted
-
 #[inline(always)]
 pub unsafe fn luaL_loadbuffer(L: *mut lua_State, s: *const c_char, sz: usize, n: *const c_char) -> c_int {
     luaL_loadbufferx(L, s, sz, n, ptr::null())
@@ -188,6 +186,96 @@ pub unsafe fn luaL_loadbufferenv(
     status
 }
 
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
+
 //
-// TODO: Generic Buffer Manipulation
+// Generic Buffer Manipulation
 //
+
+// The buffer size used by the lauxlib buffer system.
+// LUAL_BUFFERSIZE = (int)(16 * sizeof(void*) * sizeof(lua_Number))
+#[rustfmt::skip]
+pub const LUAL_BUFFERSIZE: usize = 16 * mem::size_of::<*const ()>() * mem::size_of::<lua_Number>();
+
+// Union used for the initial buffer with maximum alignment.
+// This ensures proper alignment for the buffer data.
+#[repr(C)]
+pub union luaL_BufferInit {
+    // Alignment matches LUAI_MAXALIGN
+    pub _align_n: lua_Number,
+    pub _align_u: c_double,
+    pub _align_s: *mut c_void,
+    pub _align_i: lua_Integer,
+    pub _align_l: c_long,
+    // Initial buffer space
+    pub b: [c_char; LUAL_BUFFERSIZE],
+}
+
+#[repr(C)]
+pub struct luaL_Buffer {
+    pub b: *mut c_char, // buffer address
+    pub size: usize,    // buffer size
+    pub n: usize,       // number of characters in buffer
+    pub L: *mut lua_State,
+    pub init: luaL_BufferInit, // initial buffer (union with alignment)
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua54", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Buffer);
+    pub fn luaL_prepbuffsize(B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Buffer, s: *const c_char, l: usize);
+    pub fn luaL_addstring(B: *mut luaL_Buffer, s: *const c_char);
+    pub fn luaL_addvalue(B: *mut luaL_Buffer);
+    pub fn luaL_pushresult(B: *mut luaL_Buffer);
+    pub fn luaL_pushresultsize(B: *mut luaL_Buffer, sz: usize);
+    pub fn luaL_buffinitsize(L: *mut lua_State, B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+}
+
+// Macro implementations as inline functions
+
+#[inline(always)]
+pub unsafe fn luaL_prepbuffer(B: *mut luaL_Buffer) -> *mut c_char {
+    luaL_prepbuffsize(B, LUAL_BUFFERSIZE)
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addchar(B: *mut luaL_Buffer, c: c_char) {
+    if (*B).n >= (*B).size {
+        luaL_prepbuffsize(B, 1);
+    }
+    *(*B).b.add((*B).n) = c;
+    (*B).n += 1;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addsize(B: *mut luaL_Buffer, n: usize) {
+    (*B).n += n;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_buffsub(B: *mut luaL_Buffer, n: usize) {
+    (*B).n -= n;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_bufflen(B: *mut luaL_Buffer) -> usize {
+    (*B).n
+}
+
+#[inline(always)]
+pub unsafe fn luaL_buffaddr(B: *mut luaL_Buffer) -> *mut c_char {
+    (*B).b
+}

mlua-sys/src/lua55/lauxlib.rs

@@ -0,0 +1,299 @@
+//! Contains definitions from `lauxlib.h`.
+
+use std::os::raw::{c_char, c_double, c_int, c_long, c_uint, c_void};
+use std::{mem, ptr};
+
+use super::lua::{self, lua_CFunction, lua_Integer, lua_Number, lua_State};
+
+// Extra error code for 'luaL_loadfilex'
+pub const LUA_ERRFILE: c_int = lua::LUA_ERRERR + 1;
+
+// Key, in the registry, for table of loaded modules
+pub const LUA_LOADED_TABLE: *const c_char = cstr!("_LOADED");
+
+// Key, in the registry, for table of preloaded loaders
+pub const LUA_PRELOAD_TABLE: *const c_char = cstr!("_PRELOAD");
+
+#[repr(C)]
+pub struct luaL_Reg {
+    pub name: *const c_char,
+    pub func: lua_CFunction,
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_checkversion_(L: *mut lua_State, ver: lua_Number, sz: usize);
+
+    pub fn luaL_getmetafield(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;
+    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, extramsg: *const c_char) -> c_int;
+    pub fn luaL_checklstring(L: *mut lua_State, arg: c_int, l: *mut usize) -> *const c_char;
+    pub fn luaL_optlstring(L: *mut lua_State, arg: c_int, def: *const c_char, l: *mut usize)
+    -> *const c_char;
+    pub fn luaL_checknumber(L: *mut lua_State, arg: c_int) -> lua_Number;
+    pub fn luaL_optnumber(L: *mut lua_State, arg: c_int, def: lua_Number) -> lua_Number;
+    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;
+
+    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);
+
+    pub fn luaL_newmetatable(L: *mut lua_State, tname: *const c_char) -> c_int;
+    pub fn luaL_setmetatable(L: *mut lua_State, tname: *const c_char);
+    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;
+
+    pub fn luaL_where(L: *mut lua_State, lvl: c_int);
+    pub fn luaL_error(L: *mut lua_State, fmt: *const c_char, ...) -> c_int;
+
+    pub fn luaL_checkoption(
+        L: *mut lua_State,
+        arg: c_int,
+        def: *const c_char,
+        lst: *const *const c_char,
+    ) -> c_int;
+
+    pub fn luaL_fileresult(L: *mut lua_State, stat: c_int, fname: *const c_char) -> c_int;
+    pub fn luaL_execresult(L: *mut lua_State, stat: c_int) -> c_int;
+    pub fn luaL_alloc(L: *mut lua_State, ptr: *mut c_void, osize: usize, nsize: usize) -> *mut c_void;
+}
+
+// Pre-defined references
+pub const LUA_NOREF: c_int = -2;
+pub const LUA_REFNIL: c_int = -1;
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    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#ref: c_int);
+
+    pub fn luaL_loadfilex(L: *mut lua_State, filename: *const c_char, mode: *const c_char) -> c_int;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_loadfile(L: *mut lua_State, f: *const c_char) -> c_int {
+    luaL_loadfilex(L, f, ptr::null())
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_loadbufferx(
+        L: *mut lua_State,
+        buff: *const c_char,
+        sz: usize,
+        name: *const c_char,
+        mode: *const c_char,
+    ) -> c_int;
+    pub fn luaL_loadstring(L: *mut lua_State, s: *const c_char) -> c_int;
+
+    pub fn luaL_newstate() -> *mut lua_State;
+
+    #[link_name = "luaL_makeseed"]
+    pub fn luaL_makeseed_(L: *mut lua_State) -> c_uint;
+
+    pub fn luaL_len(L: *mut lua_State, idx: c_int) -> lua_Integer;
+
+    pub fn luaL_addgsub(B: *mut luaL_Buffer, s: *const c_char, p: *const c_char, r: *const c_char);
+
+    pub fn luaL_gsub(
+        L: *mut lua_State,
+        s: *const c_char,
+        p: *const c_char,
+        r: *const c_char,
+    ) -> *const c_char;
+
+    pub fn luaL_setfuncs(L: *mut lua_State, l: *const luaL_Reg, nup: c_int);
+
+    pub fn luaL_getsubtable(L: *mut lua_State, idx: c_int, fname: *const c_char) -> c_int;
+
+    pub fn luaL_traceback(L: *mut lua_State, L1: *mut lua_State, msg: *const c_char, level: c_int);
+
+    pub fn luaL_requiref(L: *mut lua_State, modname: *const c_char, openf: lua_CFunction, glb: c_int);
+}
+
+//
+// Some useful macros (implemented as Rust functions)
+//
+
+// TODO: luaL_newlibtable, luaL_newlib
+
+#[inline(always)]
+pub unsafe fn luaL_argcheck(L: *mut lua_State, cond: c_int, arg: c_int, extramsg: *const c_char) {
+    if cond == 0 {
+        luaL_argerror(L, arg, extramsg);
+    }
+}
+
+#[inline(always)]
+pub unsafe fn luaL_checkstring(L: *mut lua_State, n: c_int) -> *const c_char {
+    luaL_checklstring(L, n, ptr::null_mut())
+}
+
+#[inline(always)]
+pub unsafe fn luaL_optstring(L: *mut lua_State, n: c_int, d: *const c_char) -> *const c_char {
+    luaL_optlstring(L, n, d, ptr::null_mut())
+}
+
+#[inline(always)]
+pub unsafe fn luaL_typename(L: *mut lua_State, i: c_int) -> *const c_char {
+    lua::lua_typename(L, lua::lua_type(L, i))
+}
+
+#[inline(always)]
+pub unsafe fn luaL_dofile(L: *mut lua_State, filename: *const c_char) -> c_int {
+    let status = luaL_loadfile(L, filename);
+    if status == 0 {
+        lua::lua_pcall(L, 0, lua::LUA_MULTRET, 0)
+    } else {
+        status
+    }
+}
+
+#[inline(always)]
+pub unsafe fn luaL_dostring(L: *mut lua_State, s: *const c_char) -> c_int {
+    let status = luaL_loadstring(L, s);
+    if status == 0 {
+        lua::lua_pcall(L, 0, lua::LUA_MULTRET, 0)
+    } else {
+        status
+    }
+}
+
+#[inline(always)]
+pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) {
+    lua::lua_getfield(L, lua::LUA_REGISTRYINDEX, n);
+}
+
+#[inline(always)]
+pub unsafe fn luaL_loadbuffer(L: *mut lua_State, s: *const c_char, sz: usize, n: *const c_char) -> c_int {
+    luaL_loadbufferx(L, s, sz, n, ptr::null())
+}
+
+pub unsafe fn luaL_loadbufferenv(
+    L: *mut lua_State,
+    data: *const c_char,
+    size: usize,
+    name: *const c_char,
+    mode: *const c_char,
+    mut env: c_int,
+) -> c_int {
+    if env != 0 {
+        env = lua::lua_absindex(L, env);
+    }
+    let status = luaL_loadbufferx(L, data, size, name, mode);
+    if status == lua::LUA_OK && env != 0 {
+        lua::lua_pushvalue(L, env);
+        lua::lua_setupvalue(L, -2, 1);
+    }
+    status
+}
+
+pub unsafe fn luaL_makeseed(L: *mut lua_State) -> c_uint {
+    #[cfg(macos)]
+    return libc::arc4random();
+    #[cfg(linux)]
+    {
+        let mut seed = 0u32;
+        let buf = &mut seed as *mut _ as *mut c_void;
+        if libc::getrandom(buf, 4, libc::GRND_NONBLOCK) == 4 {
+            return seed;
+        }
+    }
+    luaL_makeseed_(L)
+}
+
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
+
+//
+// Generic Buffer Manipulation
+//
+
+// The buffer size used by the lauxlib buffer system.
+// LUAL_BUFFERSIZE = (int)(16 * sizeof(void*) * sizeof(lua_Number))
+#[rustfmt::skip]
+pub const LUAL_BUFFERSIZE: usize = 16 * mem::size_of::<*const ()>() * mem::size_of::<lua_Number>();
+
+// Union used for the initial buffer with maximum alignment.
+// This ensures proper alignment for the buffer data.
+#[repr(C)]
+pub union luaL_BufferInit {
+    // Alignment matches LUAI_MAXALIGN
+    pub _align_n: lua_Number,
+    pub _align_u: c_double,
+    pub _align_s: *mut c_void,
+    pub _align_i: lua_Integer,
+    pub _align_l: c_long,
+    // Initial buffer space
+    pub b: [c_char; LUAL_BUFFERSIZE],
+}
+
+#[repr(C)]
+pub struct luaL_Buffer {
+    pub b: *mut c_char, // buffer address
+    pub size: usize,    // buffer size
+    pub n: usize,       // number of characters in buffer
+    pub L: *mut lua_State,
+    pub init: luaL_BufferInit, // initial buffer (union with alignment)
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Buffer);
+    pub fn luaL_prepbuffsize(B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Buffer, s: *const c_char, l: usize);
+    pub fn luaL_addstring(B: *mut luaL_Buffer, s: *const c_char);
+    pub fn luaL_addvalue(B: *mut luaL_Buffer);
+    pub fn luaL_pushresult(B: *mut luaL_Buffer);
+    pub fn luaL_pushresultsize(B: *mut luaL_Buffer, sz: usize);
+    pub fn luaL_buffinitsize(L: *mut lua_State, B: *mut luaL_Buffer, sz: usize) -> *mut c_char;
+}
+
+// Macro implementations as inline functions
+
+#[inline(always)]
+pub unsafe fn luaL_prepbuffer(B: *mut luaL_Buffer) -> *mut c_char {
+    luaL_prepbuffsize(B, LUAL_BUFFERSIZE)
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addchar(B: *mut luaL_Buffer, c: c_char) {
+    if (*B).n >= (*B).size {
+        luaL_prepbuffsize(B, 1);
+    }
+    *(*B).b.add((*B).n) = c;
+    (*B).n += 1;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addsize(B: *mut luaL_Buffer, n: usize) {
+    (*B).n += n;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_buffsub(B: *mut luaL_Buffer, n: usize) {
+    (*B).n -= n;
+}
+
+#[inline(always)]
+pub unsafe fn luaL_bufflen(B: *mut luaL_Buffer) -> usize {
+    (*B).n
+}
+
+#[inline(always)]
+pub unsafe fn luaL_buffaddr(B: *mut luaL_Buffer) -> *mut c_char {
+    (*B).b
+}

mlua-sys/src/lua55/lua.rs

@@ -0,0 +1,578 @@
+//! Contains definitions from `lua.h`.
+
+use std::ffi::CStr;
+use std::marker::{PhantomData, PhantomPinned};
+use std::os::raw::{c_char, c_double, c_int, c_uchar, c_uint, c_void};
+use std::{mem, ptr};
+
+// Mark for precompiled code (`<esc>Lua`)
+pub const LUA_SIGNATURE: &[u8] = b"\x1bLua";
+
+// Option for multiple returns in 'lua_pcall' and 'lua_call'
+pub const LUA_MULTRET: c_int = -1;
+
+// Size of the Lua stack
+#[doc(hidden)]
+pub const LUAI_MAXSTACK: c_int = c_int::MAX;
+
+// Size of a raw memory area associated with  a Lua state with very fast access.
+pub const LUA_EXTRASPACE: usize = mem::size_of::<*const ()>();
+
+//
+// Pseudo-indices
+//
+pub const LUA_REGISTRYINDEX: c_int = -(c_int::MAX / 2 + 1000);
+
+pub const fn lua_upvalueindex(i: c_int) -> c_int {
+    LUA_REGISTRYINDEX - i
+}
+
+//
+// Thread status
+//
+pub const LUA_OK: c_int = 0;
+pub const LUA_YIELD: c_int = 1;
+pub const LUA_ERRRUN: c_int = 2;
+pub const LUA_ERRSYNTAX: c_int = 3;
+pub const LUA_ERRMEM: c_int = 4;
+pub const LUA_ERRERR: c_int = 5;
+
+/// A raw Lua state associated with a thread.
+#[repr(C)]
+pub struct lua_State {
+    _data: [u8; 0],
+    _marker: PhantomData<(*mut u8, PhantomPinned)>,
+}
+
+//
+// Basic types
+//
+pub const LUA_TNONE: c_int = -1;
+
+pub const LUA_TNIL: c_int = 0;
+pub const LUA_TBOOLEAN: c_int = 1;
+pub const LUA_TLIGHTUSERDATA: c_int = 2;
+pub const LUA_TNUMBER: c_int = 3;
+pub const LUA_TSTRING: c_int = 4;
+pub const LUA_TTABLE: c_int = 5;
+pub const LUA_TFUNCTION: c_int = 6;
+pub const LUA_TUSERDATA: c_int = 7;
+pub const LUA_TTHREAD: c_int = 8;
+
+pub const LUA_NUMTYPES: c_int = 9;
+
+/// Minimum Lua stack available to a C function
+pub const LUA_MINSTACK: c_int = 20;
+
+// Predefined values in the registry
+// index 1 is reserved for the reference mechanism
+pub const LUA_RIDX_GLOBALS: lua_Integer = 2;
+pub const LUA_RIDX_MAINTHREAD: lua_Integer = 3;
+pub const LUA_RIDX_LAST: lua_Integer = 3;
+
+/// A Lua number, usually equivalent to `f64`
+pub type lua_Number = c_double;
+
+/// A Lua integer, usually equivalent to `i64`
+pub type lua_Integer = i64;
+
+/// A Lua unsigned integer, usually equivalent to `u64`
+pub type lua_Unsigned = u64;
+
+/// Type for continuation-function contexts
+pub type lua_KContext = isize;
+
+/// Type for native C functions that can be passed to Lua
+pub type lua_CFunction = unsafe extern "C-unwind" fn(L: *mut lua_State) -> c_int;
+
+/// Type for continuation functions
+pub type lua_KFunction =
+    unsafe extern "C-unwind" fn(L: *mut lua_State, status: c_int, ctx: lua_KContext) -> c_int;
+
+// Type for functions that read/write blocks when loading/dumping Lua chunks
+#[rustfmt::skip]
+pub type lua_Reader =
+    unsafe extern "C-unwind" fn(L: *mut lua_State, ud: *mut c_void, sz: *mut usize) -> *const c_char;
+#[rustfmt::skip]
+pub type lua_Writer =
+    unsafe extern "C-unwind" fn(L: *mut lua_State, p: *const c_void, sz: usize, ud: *mut c_void) -> c_int;
+
+/// Type for memory-allocation functions (no unwinding)
+#[rustfmt::skip]
+pub type lua_Alloc =
+    unsafe extern "C" fn(ud: *mut c_void, ptr: *mut c_void, osize: usize, nsize: usize) -> *mut c_void;
+
+/// Type for warning functions
+pub type lua_WarnFunction = unsafe extern "C-unwind" fn(ud: *mut c_void, msg: *const c_char, tocont: c_int);
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    //
+    // State manipulation
+    //
+    pub fn lua_newstate(f: lua_Alloc, ud: *mut c_void, seed: c_uint) -> *mut lua_State;
+    pub fn lua_close(L: *mut lua_State);
+    pub fn lua_newthread(L: *mut lua_State) -> *mut lua_State;
+    pub fn lua_closethread(L: *mut lua_State, from: *mut lua_State) -> c_int;
+
+    pub fn lua_atpanic(L: *mut lua_State, panicf: lua_CFunction) -> lua_CFunction;
+
+    pub fn lua_version(L: *mut lua_State) -> lua_Number;
+
+    //
+    // Basic stack manipulation
+    //
+    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);
+    pub fn lua_pushvalue(L: *mut lua_State, idx: c_int);
+    pub fn lua_rotate(L: *mut lua_State, idx: c_int, n: c_int);
+    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;
+
+    pub fn lua_xmove(from: *mut lua_State, to: *mut lua_State, n: c_int);
+
+    //
+    // Access functions (stack -> 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;
+    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;
+    pub fn lua_typename(L: *mut lua_State, tp: c_int) -> *const c_char;
+
+    pub fn lua_tonumberx(L: *mut lua_State, idx: c_int, isnum: *mut c_int) -> lua_Number;
+    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;
+    #[link_name = "lua_rawlen"]
+    fn lua_rawlen_(L: *mut lua_State, idx: c_int) -> lua_Unsigned;
+    pub fn lua_tocfunction(L: *mut lua_State, idx: c_int) -> Option<lua_CFunction>;
+    pub fn lua_touserdata(L: *mut lua_State, idx: c_int) -> *mut c_void;
+    pub fn lua_tothread(L: *mut lua_State, idx: c_int) -> *mut lua_State;
+    pub fn lua_topointer(L: *mut lua_State, idx: c_int) -> *const c_void;
+}
+
+// lua_rawlen's return type changed from size_t to lua_Unsigned int in Lua 5.4.
+// This adapts the crate API to the new Lua ABI.
+#[inline(always)]
+pub unsafe fn lua_rawlen(L: *mut lua_State, idx: c_int) -> usize {
+    lua_rawlen_(L, idx) as usize
+}
+
+//
+// Comparison and arithmetic functions
+//
+pub const LUA_OPADD: c_int = 0;
+pub const LUA_OPSUB: c_int = 1;
+pub const LUA_OPMUL: c_int = 2;
+pub const LUA_OPMOD: c_int = 3;
+pub const LUA_OPPOW: c_int = 4;
+pub const LUA_OPDIV: c_int = 5;
+pub const LUA_OPIDIV: c_int = 6;
+pub const LUA_OPBAND: c_int = 7;
+pub const LUA_OPBOR: c_int = 8;
+pub const LUA_OPBXOR: c_int = 9;
+pub const LUA_OPSHL: c_int = 10;
+pub const LUA_OPSHR: c_int = 11;
+pub const LUA_OPUNM: c_int = 12;
+pub const LUA_OPBNOT: c_int = 13;
+
+pub const LUA_OPEQ: c_int = 0;
+pub const LUA_OPLT: c_int = 1;
+pub const LUA_OPLE: c_int = 2;
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn lua_arith(L: *mut lua_State, op: c_int);
+    pub fn lua_rawequal(L: *mut lua_State, idx1: c_int, idx2: c_int) -> c_int;
+    pub fn lua_compare(L: *mut lua_State, idx1: c_int, idx2: c_int, op: c_int) -> c_int;
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    //
+    // Push functions (C -> stack)
+    //
+    pub fn lua_pushnil(L: *mut lua_State);
+    pub fn lua_pushnumber(L: *mut lua_State, n: lua_Number);
+    pub fn lua_pushinteger(L: *mut lua_State, n: lua_Integer);
+    pub fn lua_pushlstring(L: *mut lua_State, s: *const c_char, len: usize) -> *const c_char;
+    pub fn lua_pushexternalstring(
+        L: *mut lua_State,
+        s: *const c_char,
+        len: usize,
+        falloc: Option<lua_Alloc>,
+        ud: *mut c_void,
+    ) -> *const c_char;
+    pub fn lua_pushstring(L: *mut lua_State, s: *const c_char) -> *const c_char;
+    // lua_pushvfstring
+    pub fn lua_pushfstring(L: *mut lua_State, fmt: *const c_char, ...) -> *const c_char;
+    pub fn lua_pushcclosure(L: *mut lua_State, f: lua_CFunction, n: c_int);
+    pub fn lua_pushboolean(L: *mut lua_State, b: c_int);
+    pub fn lua_pushlightuserdata(L: *mut lua_State, p: *mut c_void);
+    pub fn lua_pushthread(L: *mut lua_State) -> c_int;
+
+    //
+    // Get functions (Lua -> stack)
+    //
+    pub fn lua_getglobal(L: *mut lua_State, name: *const c_char) -> c_int;
+    pub fn lua_gettable(L: *mut lua_State, idx: c_int) -> c_int;
+    pub fn lua_getfield(L: *mut lua_State, idx: c_int, k: *const c_char) -> c_int;
+    pub fn lua_geti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_int;
+    pub fn lua_rawget(L: *mut lua_State, idx: c_int) -> c_int;
+    pub fn lua_rawgeti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_int;
+    pub fn lua_rawgetp(L: *mut lua_State, idx: c_int, p: *const c_void) -> c_int;
+
+    pub fn lua_createtable(L: *mut lua_State, narr: c_int, nrec: c_int);
+    pub fn lua_newuserdatauv(L: *mut lua_State, sz: usize, nuvalue: c_int) -> *mut c_void;
+    pub fn lua_getmetatable(L: *mut lua_State, objindex: c_int) -> c_int;
+    pub fn lua_getiuservalue(L: *mut lua_State, idx: c_int, n: c_int) -> c_int;
+
+    //
+    // Set functions (stack -> Lua)
+    //
+    pub fn lua_setglobal(L: *mut lua_State, name: *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);
+    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);
+    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;
+    pub fn lua_setiuservalue(L: *mut lua_State, idx: c_int, n: c_int) -> c_int;
+
+    //
+    // 'load' and 'call' functions (load and run Lua code)
+    //
+    pub fn lua_callk(
+        L: *mut lua_State,
+        nargs: c_int,
+        nresults: c_int,
+        ctx: lua_KContext,
+        k: Option<lua_KFunction>,
+    );
+    pub fn lua_pcallk(
+        L: *mut lua_State,
+        nargs: c_int,
+        nresults: c_int,
+        errfunc: c_int,
+        ctx: lua_KContext,
+        k: Option<lua_KFunction>,
+    ) -> c_int;
+
+    pub fn lua_load(
+        L: *mut lua_State,
+        reader: lua_Reader,
+        data: *mut c_void,
+        chunkname: *const c_char,
+        mode: *const c_char,
+    ) -> c_int;
+
+    pub fn lua_dump(L: *mut lua_State, writer: lua_Writer, data: *mut c_void, strip: c_int) -> c_int;
+}
+
+#[inline(always)]
+pub unsafe fn lua_call(L: *mut lua_State, n: c_int, r: c_int) {
+    lua_callk(L, n, r, 0, None)
+}
+
+#[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)
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    //
+    // Coroutine functions
+    //
+    pub fn lua_yieldk(
+        L: *mut lua_State,
+        nresults: c_int,
+        ctx: lua_KContext,
+        k: Option<lua_KFunction>,
+    ) -> c_int;
+    pub fn lua_resume(L: *mut lua_State, from: *mut lua_State, narg: c_int, nres: *mut c_int) -> c_int;
+    pub fn lua_status(L: *mut lua_State) -> c_int;
+    pub fn lua_isyieldable(L: *mut lua_State) -> c_int;
+}
+
+#[inline(always)]
+pub unsafe fn lua_yield(L: *mut lua_State, n: c_int) -> c_int {
+    lua_yieldk(L, n, 0, None)
+}
+
+//
+// Warning-related functions
+//
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn lua_setwarnf(L: *mut lua_State, f: Option<lua_WarnFunction>, ud: *mut c_void);
+    pub fn lua_warning(L: *mut lua_State, msg: *const c_char, tocont: c_int);
+}
+
+//
+// Garbage-collection options
+//
+pub const LUA_GCSTOP: c_int = 0;
+pub const LUA_GCRESTART: c_int = 1;
+pub const LUA_GCCOLLECT: c_int = 2;
+pub const LUA_GCCOUNT: c_int = 3;
+pub const LUA_GCCOUNTB: c_int = 4;
+pub const LUA_GCSTEP: c_int = 5;
+pub const LUA_GCISRUNNING: c_int = 6;
+pub const LUA_GCGEN: c_int = 7;
+pub const LUA_GCINC: c_int = 8;
+pub const LUA_GCPARAM: c_int = 9;
+
+// Parameters for GC generational mode
+pub const LUA_GCPMINORMUL: c_int = 0; // control minor collections
+pub const LUA_GCPMAJORMINOR: c_int = 1; // control shift major->minor
+pub const LUA_GCPMINORMAJOR: c_int = 2; // control shift minor->major
+
+// Parameters for GC incremental mode
+pub const LUA_GCPPAUSE: c_int = 3; // size of pause between successive GCs
+pub const LUA_GCPSTEPMUL: c_int = 4; // GC "speed"
+pub const LUA_GCPSTEPSIZE: c_int = 5; // GC granularity
+
+pub const LUA_GCPNUM: c_int = 6; // number of parameters
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn lua_gc(L: *mut lua_State, what: c_int, ...) -> c_int;
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    //
+    // Miscellaneous functions
+    //
+    #[link_name = "lua_error"]
+    fn lua_error_(L: *mut lua_State) -> c_int;
+    pub fn lua_next(L: *mut lua_State, idx: c_int) -> c_int;
+    pub fn lua_concat(L: *mut lua_State, n: c_int);
+    pub fn lua_len(L: *mut lua_State, idx: c_int);
+    pub fn lua_numbertocstring(L: *mut lua_State, idx: c_int, buff: *mut c_char) -> c_uint;
+    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);
+
+    pub fn lua_toclose(L: *mut lua_State, idx: c_int);
+    pub fn lua_closeslot(L: *mut lua_State, idx: c_int);
+}
+
+// lua_error does not return but is declared to return int, and Rust translates
+// ! to void which can cause link-time errors if the platform linker is aware
+// of return types and requires they match (for example: wasm does this).
+#[inline(always)]
+pub unsafe fn lua_error(L: *mut lua_State) -> ! {
+    lua_error_(L);
+    unreachable!();
+}
+
+//
+// Some useful macros (implemented as Rust functions)
+//
+#[inline(always)]
+pub unsafe fn lua_getextraspace(L: *mut lua_State) -> *mut c_void {
+    (L as *mut c_char).sub(LUA_EXTRASPACE) as *mut c_void
+}
+
+#[inline(always)]
+pub unsafe fn lua_tonumber(L: *mut lua_State, i: c_int) -> lua_Number {
+    lua_tonumberx(L, i, ptr::null_mut())
+}
+
+#[inline(always)]
+pub unsafe fn lua_tointeger(L: *mut lua_State, i: c_int) -> lua_Integer {
+    lua_tointegerx(L, i, ptr::null_mut())
+}
+
+#[inline(always)]
+pub unsafe fn lua_pop(L: *mut lua_State, n: c_int) {
+    lua_settop(L, -n - 1)
+}
+
+#[inline(always)]
+pub unsafe fn lua_newtable(L: *mut lua_State) {
+    lua_createtable(L, 0, 0)
+}
+
+#[inline(always)]
+pub unsafe fn lua_register(L: *mut lua_State, n: *const c_char, f: lua_CFunction) {
+    lua_pushcfunction(L, f);
+    lua_setglobal(L, n)
+}
+
+#[inline(always)]
+pub unsafe fn lua_pushcfunction(L: *mut lua_State, f: lua_CFunction) {
+    lua_pushcclosure(L, f, 0)
+}
+
+#[inline(always)]
+pub unsafe fn lua_isfunction(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TFUNCTION) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_istable(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TTABLE) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_islightuserdata(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TLIGHTUSERDATA) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_isnil(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TNIL) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_isboolean(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TBOOLEAN) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_isthread(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TTHREAD) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_isnone(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TNONE) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_isnoneornil(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) <= 0) as c_int
+}
+
+#[inline(always)]
+pub unsafe fn lua_pushliteral(L: *mut lua_State, s: &'static CStr) {
+    lua_pushstring(L, s.as_ptr());
+}
+
+#[inline(always)]
+pub unsafe fn lua_pushglobaltable(L: *mut lua_State) -> c_int {
+    lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_GLOBALS)
+}
+
+#[inline(always)]
+pub unsafe fn lua_tolightuserdata(L: *mut lua_State, idx: c_int) -> *mut c_void {
+    if lua_islightuserdata(L, idx) != 0 {
+        return lua_touserdata(L, idx);
+    }
+    ptr::null_mut()
+}
+
+#[inline(always)]
+pub unsafe fn lua_tostring(L: *mut lua_State, i: c_int) -> *const c_char {
+    lua_tolstring(L, i, ptr::null_mut())
+}
+
+#[inline(always)]
+pub unsafe fn lua_insert(L: *mut lua_State, idx: c_int) {
+    lua_rotate(L, idx, 1)
+}
+
+#[inline(always)]
+pub unsafe fn lua_remove(L: *mut lua_State, idx: c_int) {
+    lua_rotate(L, idx, -1);
+    lua_pop(L, 1)
+}
+
+#[inline(always)]
+pub unsafe fn lua_replace(L: *mut lua_State, idx: c_int) {
+    lua_copy(L, -1, idx);
+    lua_pop(L, 1)
+}
+
+#[inline(always)]
+pub unsafe fn lua_xpush(from: *mut lua_State, to: *mut lua_State, idx: c_int) {
+    lua_pushvalue(from, idx);
+    lua_xmove(from, to, 1);
+}
+
+#[inline(always)]
+pub unsafe fn lua_newuserdata(L: *mut lua_State, sz: usize) -> *mut c_void {
+    lua_newuserdatauv(L, sz, 1)
+}
+
+#[inline(always)]
+pub unsafe fn lua_getuservalue(L: *mut lua_State, idx: c_int) -> c_int {
+    lua_getiuservalue(L, idx, 1)
+}
+
+#[inline(always)]
+pub unsafe fn lua_setuservalue(L: *mut lua_State, idx: c_int) -> c_int {
+    lua_setiuservalue(L, idx, 1)
+}
+
+//
+// Debug API
+//
+
+// Maximum size for the description of the source of a function in debug information.
+const LUA_IDSIZE: usize = 60;
+
+// Event codes
+pub const LUA_HOOKCALL: c_int = 0;
+pub const LUA_HOOKRET: c_int = 1;
+pub const LUA_HOOKLINE: c_int = 2;
+pub const LUA_HOOKCOUNT: c_int = 3;
+pub const LUA_HOOKTAILCALL: c_int = 4;
+
+// Event masks
+pub const LUA_MASKCALL: c_int = 1 << (LUA_HOOKCALL as usize);
+pub const LUA_MASKRET: c_int = 1 << (LUA_HOOKRET as usize);
+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 = unsafe extern "C-unwind" fn(L: *mut lua_State, ar: *mut lua_Debug);
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn lua_getstack(L: *mut lua_State, level: c_int, ar: *mut lua_Debug) -> c_int;
+    pub fn lua_getinfo(L: *mut lua_State, what: *const c_char, ar: *mut lua_Debug) -> c_int;
+    pub fn lua_getlocal(L: *mut lua_State, ar: *const lua_Debug, n: c_int) -> *const c_char;
+    pub fn lua_setlocal(L: *mut lua_State, ar: *const lua_Debug, n: c_int) -> *const c_char;
+    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;
+
+    pub fn lua_upvalueid(L: *mut lua_State, fidx: c_int, n: c_int) -> *mut c_void;
+    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: 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;
+}
+
+#[repr(C)]
+pub struct lua_Debug {
+    pub event: c_int,
+    pub name: *const c_char,             // (n)
+    pub namewhat: *const c_char,         // (n) 'global', 'local', 'field', 'method'
+    pub what: *const c_char,             // (S) 'Lua', 'C', 'main', 'tail'
+    pub source: *const c_char,           // (S)
+    pub srclen: usize,                   // (S)
+    pub currentline: c_int,              // (l)
+    pub linedefined: c_int,              // (S)
+    pub lastlinedefined: c_int,          // (S)
+    pub nups: c_uchar,                   // (u) number of upvalues
+    pub nparams: c_uchar,                // (u) number of parameters
+    pub isvararg: c_char,                // (u)
+    pub extraargs: c_uchar,              // (t) number of extra arguments
+    pub istailcall: c_char,              // (t)
+    pub ftransfer: c_int,                // (r) index of first value transferred
+    pub ntransfer: c_int,                // (r) number of transferred values
+    pub short_src: [c_char; LUA_IDSIZE], // (S)
+    // lua.h mentions this is for private use
+    i_ci: *mut c_void,
+}

mlua-sys/src/lua55/lualib.rs

@@ -0,0 +1,55 @@
+//! Contains definitions from `lualib.h`.
+
+use std::os::raw::{c_char, c_int};
+
+use super::lua::lua_State;
+
+pub const LUA_GLIBK: c_int = 1;
+
+pub const LUA_LOADLIBNAME: *const c_char = cstr!("package");
+pub const LUA_LOADLIBK: c_int = LUA_GLIBK << 1;
+
+pub const LUA_COLIBNAME: *const c_char = cstr!("coroutine");
+pub const LUA_COLIBK: c_int = LUA_GLIBK << 2;
+
+pub const LUA_DBLIBNAME: *const c_char = cstr!("debug");
+pub const LUA_DBLIBK: c_int = LUA_GLIBK << 3;
+
+pub const LUA_IOLIBNAME: *const c_char = cstr!("io");
+pub const LUA_IOLIBK: c_int = LUA_GLIBK << 4;
+
+pub const LUA_MATHLIBNAME: *const c_char = cstr!("math");
+pub const LUA_MATHLIBK: c_int = LUA_GLIBK << 5;
+
+pub const LUA_OSLIBNAME: *const c_char = cstr!("os");
+pub const LUA_OSLIBK: c_int = LUA_GLIBK << 6;
+
+pub const LUA_STRLIBNAME: *const c_char = cstr!("string");
+pub const LUA_STRLIBK: c_int = LUA_GLIBK << 7;
+
+pub const LUA_TABLIBNAME: *const c_char = cstr!("table");
+pub const LUA_TABLIBK: c_int = LUA_GLIBK << 8;
+
+pub const LUA_UTF8LIBNAME: *const c_char = cstr!("utf8");
+pub const LUA_UTF8LIBK: c_int = LUA_GLIBK << 9;
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua55", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaopen_base(L: *mut lua_State) -> c_int;
+    pub fn luaopen_package(L: *mut lua_State) -> c_int;
+    pub fn luaopen_coroutine(L: *mut lua_State) -> c_int;
+    pub fn luaopen_debug(L: *mut lua_State) -> c_int;
+    pub fn luaopen_io(L: *mut lua_State) -> c_int;
+    pub fn luaopen_math(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;
+    pub fn luaopen_table(L: *mut lua_State) -> c_int;
+    pub fn luaopen_utf8(L: *mut lua_State) -> c_int;
+
+    // open all builtin libraries
+    pub fn luaL_openselectedlibs(L: *mut lua_State, load: c_int, preload: c_int);
+}
+
+pub unsafe fn luaL_openlibs(L: *mut lua_State) {
+    luaL_openselectedlibs(L, !0, 0);
+}

mlua-sys/src/lua55/mod.rs

@@ -0,0 +1,9 @@
+//! Low level bindings to Lua 5.5.
+
+pub use lauxlib::*;
+pub use lua::*;
+pub use lualib::*;
+
+pub mod lauxlib;
+pub mod lua;
+pub mod lualib;

mlua-sys/src/luau/compat.rs

@@ -23,8 +23,8 @@ unsafe fn compat53_reverse(L: *mut lua_State, mut a: c_int, mut b: c_int) {
     }
 }
 
-const COMPAT53_LEVELS1: c_int = 12; // size of the first part of the stack
-const COMPAT53_LEVELS2: c_int = 10; // size of the second part of the stack
+const COMPAT53_LEVELS1: c_int = 10; // size of the first part of the stack
+const COMPAT53_LEVELS2: c_int = 11; // size of the second part of the stack
 
 unsafe fn compat53_findfield(L: *mut lua_State, objidx: c_int, level: c_int) -> c_int {
     if level == 0 || lua_istable(L, -1) == 0 {
@@ -41,11 +41,10 @@ unsafe fn compat53_findfield(L: *mut lua_State, objidx: c_int, level: c_int) ->
                 lua_pop(L, 1); // remove value (but keep name)
                 return 1;
             } else if compat53_findfield(L, objidx, level - 1) != 0 {
-                // try recursively
-                lua_remove(L, -2); // remove table (but keep name)
-                lua_pushliteral(L, c".");
-                lua_insert(L, -2); // place '.' between the two names
-                lua_concat(L, 3);
+                // stack: lib_name, lib_table, field_name (top)
+                lua_pushliteral(L, c"."); // place '.' between the two names
+                lua_replace(L, -3); // (in the slot occupied by table)
+                lua_concat(L, 3); // lib_name.field_name
                 return 1;
             }
         }
@@ -54,14 +53,25 @@ unsafe fn compat53_findfield(L: *mut lua_State, objidx: c_int, level: c_int) ->
     0 // not found
 }
 
-unsafe fn compat53_pushglobalfuncname(L: *mut lua_State, level: c_int, ar: *mut lua_Debug) -> c_int {
+unsafe fn compat53_pushglobalfuncname(
+    L: *mut lua_State,
+    L1: *mut lua_State,
+    level: c_int,
+    ar: *mut lua_Debug,
+) -> c_int {
     let top = lua_gettop(L);
-    // push function
-    lua_getinfo(L, level, cstr!("f"), ar);
+    lua_getinfo(L1, level, cstr!("f"), ar); // push function
+    lua_xmove(L1, L, 1); // and move onto L
     lua_pushvalue(L, LUA_GLOBALSINDEX);
+    luaL_checkstack(L, 6, cstr!("not enough stack")); // slots for 'findfield'
     if compat53_findfield(L, top + 1, 2) != 0 {
+        let name = lua_tostring(L, -1);
+        if CStr::from_ptr(name).to_bytes().starts_with(b"_G.") {
+            lua_pushstring(L, name.add(3)); // push name without prefix
+            lua_remove(L, -2); // remove original name
+        }
         lua_copy(L, -1, top + 1); // move name to proper place
-        lua_pop(L, 2); // remove pushed values
+        lua_settop(L, top + 1); // remove pushed values
         1
     } else {
         lua_settop(L, top); // remove function and global table
@@ -69,13 +79,16 @@ unsafe fn compat53_pushglobalfuncname(L: *mut lua_State, level: c_int, ar: *mut
     }
 }
 
-unsafe fn compat53_pushfuncname(L: *mut lua_State, level: c_int, ar: *mut lua_Debug) {
+unsafe fn compat53_pushfuncname(L: *mut lua_State, L1: *mut lua_State, level: c_int, ar: *mut lua_Debug) {
     if !(*ar).name.is_null() {
         // is there a name?
         lua_pushfstring(L, cstr!("function '%s'"), (*ar).name);
-    } else if compat53_pushglobalfuncname(L, level, ar) != 0 {
+    } else if compat53_pushglobalfuncname(L, L1, level, ar) != 0 {
         lua_pushfstring(L, cstr!("function '%s'"), lua_tostring(L, -1));
         lua_remove(L, -2); // remove name
+    } else if *(*ar).what != b'C' as c_char {
+        // for Lua functions, use <file:line>
+        lua_pushfstring(L, cstr!("function <%s:%d>"), (*ar).short_src, (*ar).linedefined);
     } else {
         lua_pushliteral(L, c"?");
     }
@@ -120,7 +133,8 @@ pub unsafe fn lua_isinteger(L: *mut lua_State, idx: c_int) -> c_int {
     if lua_type(L, idx) == LUA_TNUMBER {
         let n = lua_tonumber(L, idx);
         let i = lua_tointeger(L, idx);
-        if (n - i as lua_Number).abs() < lua_Number::EPSILON {
+        // Lua 5.3+ returns "false" for `-0.0`
+        if n.to_bits() == (i as lua_Number).to_bits() {
             return 1;
         }
     }
@@ -189,9 +203,7 @@ pub unsafe fn lua_rawgeti(L: *mut lua_State, idx: c_int, n: lua_Integer) -> c_in
 
 #[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);
-    lua_rawget(L, abs_i)
+    lua_rawgetptagged(L, idx, p, 0)
 }
 
 #[inline(always)]
@@ -225,11 +237,7 @@ pub unsafe fn lua_rawseti(L: *mut lua_State, idx: c_int, n: lua_Integer) {
 
 #[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 available"));
-    lua_pushlightuserdata(L, p as *mut c_void);
-    lua_insert(L, -2);
-    lua_rawset(L, abs_i);
+    lua_rawsetptagged(L, idx, p, 0)
 }
 
 #[inline(always)]
@@ -388,7 +396,7 @@ pub unsafe fn luaL_loadbufferenv(
         }
     }
 
-    if chunk_is_text {
+    let status = if chunk_is_text {
         if env < 0 {
             env -= 1;
         }
@@ -397,14 +405,21 @@ pub unsafe fn luaL_loadbufferenv(
         ptr::write(data_ud, data);
         // By deferring the `free(data)` to the userdata destructor, we ensure that
         // even if `luau_load` throws an error, the `data` is still released.
-        let ok = luau_load(L, name, data, size, env) == 0;
+        let status = luau_load(L, name, data, size, env);
         lua_replace(L, -2); // replace data with the result
-        if !ok {
-            return LUA_ERRSYNTAX;
+        status
+    } else {
+        luau_load(L, name, data, size, env)
+    };
+
+    if status != 0 {
+        if lua_isstring(L, -1) != 0 && CStr::from_ptr(lua_tostring(L, -1)) == c"not enough memory" {
+            // A case for Luau >= 0.679
+            return LUA_ERRMEM;
         }
-    } else if luau_load(L, name, data, size, env) != 0 {
         return LUA_ERRSYNTAX;
     }
+
     LUA_OK
 }
 
@@ -444,36 +459,42 @@ pub unsafe fn luaL_len(L: *mut lua_State, idx: c_int) -> lua_Integer {
 
 pub unsafe fn luaL_traceback(L: *mut lua_State, L1: *mut lua_State, msg: *const c_char, mut level: c_int) {
     let mut ar: lua_Debug = mem::zeroed();
-    let top = lua_gettop(L);
     let numlevels = lua_stackdepth(L);
-    let mark = if numlevels > COMPAT53_LEVELS1 + COMPAT53_LEVELS2 {
-        COMPAT53_LEVELS1
-    } else {
-        0
-    };
+    #[rustfmt::skip]
+    let mut limit = if numlevels - level > COMPAT53_LEVELS1 + COMPAT53_LEVELS2 { COMPAT53_LEVELS1 } else { -1 };
+
+    let mut buf: luaL_Strbuf = mem::zeroed();
+    luaL_buffinit(L, &mut buf);
 
     if !msg.is_null() {
-        lua_pushfstring(L, cstr!("%s\n"), msg);
+        luaL_addstring(&mut buf, msg);
+        luaL_addstring(&mut buf, cstr!("\n"));
     }
-    lua_pushliteral(L, c"stack traceback:");
-    while lua_getinfo(L1, level, cstr!(""), &mut ar) != 0 {
-        if level + 1 == mark {
+    luaL_addstring(&mut buf, cstr!("stack traceback:"));
+    while lua_getinfo(L1, level, cstr!("sln"), &mut ar) != 0 {
+        if limit == 0 {
             // too many levels?
-            lua_pushliteral(L, c"\n\t..."); // add a '...'
-            level = numlevels - COMPAT53_LEVELS2; // and skip to last ones
+            let n = numlevels - level - COMPAT53_LEVELS2;
+            // add warning about skip ("n + 1" because we skip current level too)
+            lua_pushfstring(L, cstr!("\n\t...\t(skipping %d levels)"), n + 1);
+            luaL_addvalue(&mut buf);
+            level += n; // and skip to last levels
         } else {
-            lua_getinfo(L1, level, cstr!("sln"), &mut ar);
-            lua_pushfstring(L, cstr!("\n\t%s:"), ar.short_src);
+            luaL_addstring(&mut buf, cstr!("\n\t"));
+            luaL_addstring(&mut buf, ar.short_src);
+            luaL_addstring(&mut buf, cstr!(":"));
             if ar.currentline > 0 {
-                lua_pushfstring(L, cstr!("%d:"), ar.currentline);
+                luaL_addunsigned(&mut buf, ar.currentline as _);
+                luaL_addstring(&mut buf, cstr!(":"));
             }
-            lua_pushliteral(L, c" in ");
-            compat53_pushfuncname(L, level, &mut ar);
-            lua_concat(L, lua_gettop(L) - top);
+            luaL_addstring(&mut buf, cstr!(" in "));
+            compat53_pushfuncname(L, L1, level, &mut ar);
+            luaL_addvalue(&mut buf);
         }
         level += 1;
+        limit -= 1;
     }
-    lua_concat(L, lua_gettop(L) - top);
+    luaL_pushresult(&mut buf);
 }
 
 pub unsafe fn luaL_tolstring(L: *mut lua_State, mut idx: c_int, len: *mut usize) -> *const c_char {
@@ -536,7 +557,7 @@ pub unsafe fn luaL_getsubtable(L: *mut lua_State, idx: c_int, fname: *const c_ch
 
 pub unsafe fn luaL_requiref(L: *mut lua_State, modname: *const c_char, openf: lua_CFunction, glb: c_int) {
     luaL_checkstack(L, 3, cstr!("not enough stack slots available"));
-    luaL_getsubtable(L, LUA_REGISTRYINDEX, cstr!("_LOADED"));
+    luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
     if lua_getfield(L, -1, modname) == LUA_TNIL {
         lua_pop(L, 1);
         lua_pushcfunction(L, openf);

mlua-sys/src/luau/lauxlib.rs

@@ -3,7 +3,10 @@
 use std::os::raw::{c_char, c_float, c_int, c_void};
 use std::ptr;
 
-use super::lua::{self, lua_CFunction, lua_Number, lua_State, lua_Unsigned, LUA_REGISTRYINDEX};
+use super::lua::{self, LUA_REGISTRYINDEX, lua_CFunction, lua_Number, lua_State, lua_Unsigned};
+
+// Key, in the registry, for table of loaded modules
+pub const LUA_LOADED_TABLE: *const c_char = cstr!("_LOADED");
 
 #[repr(C)]
 pub struct luaL_Reg {
@@ -82,6 +85,9 @@ unsafe extern "C-unwind" {
 
     pub fn luaL_callyieldable(L: *mut lua_State, nargs: c_int, nresults: c_int) -> c_int;
 
+    #[link_name = "luaL_traceback"]
+    pub fn luaL_traceback_(L: *mut lua_State, L1: *mut lua_State, msg: *const c_char, level: c_int);
+
     // sandbox libraries and globals
     #[link_name = "luaL_sandbox"]
     pub fn luaL_sandbox_(L: *mut lua_State);
@@ -116,7 +122,19 @@ pub unsafe fn luaL_optstring(L: *mut lua_State, n: c_int, d: *const c_char) -> *
     luaL_optlstring(L, n, d, ptr::null_mut())
 }
 
-// TODO: luaL_opt
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
 
 #[inline(always)]
 pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) -> c_int {
@@ -209,3 +227,18 @@ pub unsafe fn luaL_addstring(B: *mut luaL_Strbuf, s: *const c_char) {
     }
     luaL_addlstring(B, s, len);
 }
+
+pub unsafe fn luaL_addunsigned(B: *mut luaL_Strbuf, mut n: lua_Unsigned) {
+    let mut buf: [c_char; 32] = [0; 32];
+    let mut i = 32;
+    loop {
+        i -= 1;
+        let digit = (n % 10) as u8;
+        buf[i] = (b'0' + digit) as c_char;
+        n /= 10;
+        if n == 0 {
+            break;
+        }
+    }
+    luaL_addlstring(B, buf.as_ptr().add(i), 32 - i);
+}

mlua-sys/src/luau/lua.rs

@@ -37,6 +37,16 @@ pub const LUA_ERRRUN: c_int = 2;
 pub const LUA_ERRSYNTAX: c_int = 3;
 pub const LUA_ERRMEM: c_int = 4;
 pub const LUA_ERRERR: c_int = 5;
+pub const LUA_BREAK: c_int = 6; // yielded for a debug breakpoint
+
+//
+// Coroutine status
+//
+pub const LUA_CORUN: c_int = 0; // running
+pub const LUA_COSUS: c_int = 1; // suspended
+pub const LUA_CONOR: c_int = 2; // 'normal' (it resumed another coroutine)
+pub const LUA_COFIN: c_int = 3; // finished
+pub const LUA_COERR: c_int = 4; // finished with error
 
 /// A raw Lua state associated with a thread.
 #[repr(C)]
@@ -145,8 +155,15 @@ unsafe extern "C-unwind" {
     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;
     pub fn lua_tostringatom(L: *mut lua_State, idx: c_int, atom: *mut c_int) -> *const c_char;
+    pub fn lua_tolstringatom(
+        L: *mut lua_State,
+        idx: c_int,
+        len: *mut usize,
+        atom: *mut c_int,
+    ) -> *const c_char;
     pub fn lua_namecallatom(L: *mut lua_State, atom: *mut c_int) -> *const c_char;
-    pub fn lua_objlen(L: *mut lua_State, idx: c_int) -> usize;
+    #[link_name = "lua_objlen"]
+    pub fn lua_objlen_(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_tocfunction(L: *mut lua_State, idx: c_int) -> Option<lua_CFunction>;
     pub fn lua_tolightuserdata(L: *mut lua_State, idx: c_int) -> *mut c_void;
     pub fn lua_tolightuserdatatagged(L: *mut lua_State, idx: c_int, tag: c_int) -> *mut c_void;
@@ -203,6 +220,7 @@ unsafe extern "C-unwind" {
     pub fn lua_rawget(L: *mut lua_State, idx: c_int) -> c_int;
     #[link_name = "lua_rawgeti"]
     pub fn lua_rawgeti_(L: *mut lua_State, idx: c_int, n: c_int) -> c_int;
+    pub fn lua_rawgetptagged(L: *mut lua_State, idx: c_int, p: *const c_void, tag: c_int) -> c_int;
     pub fn lua_createtable(L: *mut lua_State, narr: c_int, nrec: c_int);
 
     pub fn lua_setreadonly(L: *mut lua_State, idx: c_int, enabled: c_int);
@@ -217,9 +235,11 @@ unsafe extern "C-unwind" {
     //
     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);
+    pub fn lua_rawsetfield(L: *mut lua_State, idx: c_int, k: *const c_char);
     pub fn lua_rawset(L: *mut lua_State, idx: c_int);
     #[link_name = "lua_rawseti"]
     pub fn lua_rawseti_(L: *mut lua_State, idx: c_int, n: c_int);
+    pub fn lua_rawsetptagged(L: *mut lua_State, idx: c_int, p: *const c_void, tag: c_int);
     pub fn lua_setmetatable(L: *mut lua_State, objindex: c_int) -> c_int;
     pub fn lua_setfenv(L: *mut lua_State, idx: c_int) -> c_int;
 
@@ -235,6 +255,7 @@ unsafe extern "C-unwind" {
     ) -> c_int;
     pub fn lua_call(L: *mut lua_State, nargs: c_int, nresults: c_int);
     pub fn lua_pcall(L: *mut lua_State, nargs: c_int, nresults: c_int, errfunc: c_int) -> c_int;
+    pub fn lua_cpcall(L: *mut lua_State, f: lua_CFunction, ud: *mut c_void) -> c_int;
 
     //
     // Coroutine functions
@@ -248,6 +269,12 @@ unsafe extern "C-unwind" {
     pub fn lua_isyieldable(L: *mut lua_State) -> c_int;
     pub fn lua_getthreaddata(L: *mut lua_State) -> *mut c_void;
     pub fn lua_setthreaddata(L: *mut lua_State, data: *mut c_void);
+    pub fn lua_costatus(L: *mut lua_State, co: *mut lua_State) -> c_int;
+}
+
+#[inline(always)]
+pub unsafe fn lua_objlen(L: *mut lua_State, idx: c_int) -> usize {
+    lua_objlen_(L, idx) as usize
 }
 
 //
@@ -284,7 +311,7 @@ unsafe extern "C-unwind" {
     pub fn lua_next(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_rawiter(L: *mut lua_State, idx: c_int, iter: c_int) -> c_int;
     pub fn lua_concat(L: *mut lua_State, n: c_int);
-    // TODO: lua_encodepointer
+    pub fn lua_encodepointer(L: *mut lua_State, p: usize) -> usize;
     pub fn lua_clock() -> c_double;
     pub fn lua_setuserdatatag(L: *mut lua_State, idx: c_int, tag: c_int);
     pub fn lua_setuserdatadtor(L: *mut lua_State, tag: c_int, dtor: Option<lua_Destructor>);
@@ -295,6 +322,7 @@ unsafe extern "C-unwind" {
     pub fn lua_getlightuserdataname(L: *mut lua_State, tag: c_int) -> *const c_char;
     pub fn lua_clonefunction(L: *mut lua_State, idx: c_int);
     pub fn lua_cleartable(L: *mut lua_State, idx: c_int);
+    pub fn lua_clonetable(L: *mut lua_State, idx: c_int);
     pub fn lua_getallocf(L: *mut lua_State, ud: *mut *mut c_void) -> lua_Alloc;
 }
 
@@ -354,7 +382,10 @@ pub unsafe fn lua_newuserdata_t<T>(L: *mut lua_State, data: T) -> *mut T {
     ud_ptr
 }
 
-// TODO: lua_strlen
+#[inline(always)]
+pub unsafe fn lua_strlen(L: *mut lua_State, i: c_int) -> usize {
+    lua_objlen(L, i)
+}
 
 #[inline(always)]
 pub unsafe fn lua_isfunction(L: *mut lua_State, n: c_int) -> c_int {
@@ -544,4 +575,9 @@ unsafe extern "C" {
 unsafe extern "C" {
     pub fn luau_setfflag(name: *const c_char, value: c_int) -> c_int;
     pub fn lua_getmetatablepointer(L: *mut lua_State, idx: c_int) -> *const c_void;
+    pub fn lua_gcdump(
+        L: *mut lua_State,
+        file: *mut c_void,
+        category_name: Option<unsafe extern "C" fn(L: *mut lua_State, memcat: u8) -> *const c_char>,
+    );
 }

mlua-sys/src/luau/luarequire.rs

@@ -23,6 +23,16 @@ pub enum luarequire_WriteResult {
     Failure,
 }
 
+/// Represents whether a configuration file is present, and if so, its syntax.
+#[repr(C)]
+pub enum luarequire_ConfigStatus {
+    Absent,
+    // Signals the presence of multiple configuration files
+    Ambiguous,
+    PresentJson,
+    PresentLuau,
+}
+
 #[repr(C)]
 pub struct luarequire_Configuration {
     // Returns whether requires are permitted from the given chunkname.
@@ -48,6 +58,29 @@ pub struct luarequire_Configuration {
         path: *const c_char,
     ) -> luarequire_NavigateResult,
 
+    // Provides an initial alias override opportunity prior to searching for configuration files.
+    // If NAVIGATE_SUCCESS is returned, the internal state must be updated to point at the
+    // aliased location.
+    // Can be left undefined.
+    pub to_alias_override: Option<
+        unsafe extern "C-unwind" fn(
+            L: *mut lua_State,
+            ctx: *mut c_void,
+            alias_unprefixed: *const c_char,
+        ) -> luarequire_NavigateResult,
+    >,
+
+    // Provides a final override opportunity if an alias cannot be found in configuration files. If
+    // NAVIGATE_SUCCESS is returned, this must update the internal state to point at the aliased module.
+    // Can be left undefined.
+    pub to_alias_fallback: Option<
+        unsafe extern "C-unwind" fn(
+            L: *mut lua_State,
+            ctx: *mut c_void,
+            alias_unprefixed: *const c_char,
+        ) -> luarequire_NavigateResult,
+    >,
+
     // Navigates through the context by making mutations to the internal state.
     pub to_parent:
         unsafe extern "C-unwind" fn(L: *mut lua_State, ctx: *mut c_void) -> luarequire_NavigateResult,
@@ -90,13 +123,14 @@ pub struct luarequire_Configuration {
         size_out: *mut usize,
     ) -> luarequire_WriteResult,
 
-    // Returns whether a configuration file is present in the current context.
-    // If not, require-by-string will call to_parent until either a configuration file is present or
+    // Returns whether a configuration file is present in the current context, and if so, its syntax.
+    // If not present, require-by-string will call to_parent until either a configuration file is present or
     // NAVIGATE_FAILURE is returned (at root).
-    pub is_config_present: unsafe extern "C-unwind" fn(L: *mut lua_State, ctx: *mut c_void) -> bool,
+    pub get_config_status:
+        unsafe extern "C-unwind" fn(L: *mut lua_State, ctx: *mut c_void) -> luarequire_ConfigStatus,
 
     // Parses the configuration file in the current context for the given alias and returns its
-    // value or WRITE_FAILURE if not found. This function is only called if is_config_present
+    // value or WRITE_FAILURE if not found. This function is only called if get_config_status
     // returns true. If this function pointer is set, get_config must not be set. Opting in to this
     // function pointer disables parsing configuration files internally and can be used for finer
     // control over the configuration file parsing process.
@@ -111,9 +145,10 @@ pub struct luarequire_Configuration {
         ) -> luarequire_WriteResult,
     >,
 
-    // Provides the contents of the configuration file in the current context. This function is only called
-    // if is_config_present returns true. If this function pointer is set, get_alias must not be set. Opting
-    // in to this function pointer enables parsing configuration files internally.
+    // Provides the contents of the configuration file in the current context.
+    // This function is only called if get_config_status does not return CONFIG_ABSENT. If this function
+    // pointer is set, get_alias must not be set. Opting in to this function pointer enables parsing
+    // configuration files internally.
     pub get_config: Option<
         unsafe extern "C-unwind" fn(
             L: *mut lua_State,
@@ -124,6 +159,13 @@ pub struct luarequire_Configuration {
         ) -> luarequire_WriteResult,
     >,
 
+    // Returns the maximum number of milliseconds to allow for executing a given Luau-syntax configuration
+    // file. This function is only called if get_config_status returns CONFIG_PRESENT_LUAU and can be left
+    // undefined if support for Luau-syntax configuration files is not needed. A default value of 2000ms is
+    // used. Negative values are treated as infinite.
+    pub get_luau_config_timeout:
+        Option<unsafe extern "C-unwind" fn(L: *mut lua_State, ctx: *mut c_void) -> c_int>,
+
     // Executes the module and places the result on the stack. Returns the number of results placed on the
     // stack.
     // Returning -1 directs the requiring thread to yield. In this case, this thread should be resumed with

mlua_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mlua_derive"
-version = "0.11.0-beta.2"
+version = "0.11.0"
 authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
 edition = "2021"
 description = "Procedural macros for the mlua crate."

mlua_derive/src/lib.rs

@@ -129,13 +129,13 @@ pub fn chunk(input: TokenStream) -> TokenStream {
             let globals = lua.globals();
             let env = lua.create_table()?;
             let meta = lua.create_table()?;
-            meta.raw_set("__index", globals.clone())?;
-            meta.raw_set("__newindex", globals)?;
+            meta.raw_set("__index", &globals)?;
+            meta.raw_set("__newindex", &globals)?;
 
             // Add captured variables
             #(#caps)*
 
-            env.set_metatable(Some(meta));
+            env.set_metatable(Some(meta))?;
             Ok(env)
         };
 

src/buffer.rs

@@ -1,6 +1,9 @@
+use std::io;
+
 #[cfg(feature = "serde")]
 use serde::ser::{Serialize, Serializer};
 
+use crate::state::RawLua;
 use crate::types::ValueRef;
 
 /// A Luau buffer type.
@@ -16,12 +19,14 @@ pub struct Buffer(pub(crate) ValueRef);
 impl Buffer {
     /// Copies the buffer data into a new `Vec<u8>`.
     pub fn to_vec(&self) -> Vec<u8> {
-        unsafe { self.as_slice().to_vec() }
+        let lua = self.0.lua.lock();
+        self.as_slice(&lua).to_vec()
     }
 
     /// Returns the length of the buffer.
     pub fn len(&self) -> usize {
-        unsafe { self.as_slice().len() }
+        let lua = self.0.lua.lock();
+        self.as_slice(&lua).len()
     }
 
     /// Returns `true` if the buffer is empty.
@@ -34,7 +39,8 @@ impl Buffer {
     /// Offset is 0-based.
     #[track_caller]
     pub fn read_bytes<const N: usize>(&self, offset: usize) -> [u8; N] {
-        let data = unsafe { self.as_slice() };
+        let lua = self.0.lua.lock();
+        let data = self.as_slice(&lua);
         let mut bytes = [0u8; N];
         bytes.copy_from_slice(&data[offset..offset + N]);
         bytes
@@ -45,21 +51,36 @@ impl Buffer {
     /// Offset is 0-based.
     #[track_caller]
     pub fn write_bytes(&self, offset: usize, bytes: &[u8]) {
-        let data = unsafe {
-            let (buf, size) = self.as_raw_parts();
-            std::slice::from_raw_parts_mut(buf, size)
-        };
+        let lua = self.0.lua.lock();
+        let data = self.as_slice_mut(&lua);
         data[offset..offset + bytes.len()].copy_from_slice(bytes);
     }
 
-    pub(crate) unsafe fn as_slice(&self) -> &[u8] {
-        let (buf, size) = self.as_raw_parts();
-        std::slice::from_raw_parts(buf, size)
+    /// Returns an adaptor implementing [`io::Read`], [`io::Write`] and [`io::Seek`] over the
+    /// buffer.
+    ///
+    /// Buffer operations are infallible, none of the read/write functions will return a Err.
+    pub fn cursor(self) -> impl io::Read + io::Write + io::Seek {
+        BufferCursor(self, 0)
+    }
+
+    pub(crate) fn as_slice(&self, lua: &RawLua) -> &[u8] {
+        unsafe {
+            let (buf, size) = self.as_raw_parts(lua);
+            std::slice::from_raw_parts(buf, size)
+        }
+    }
+
+    #[allow(clippy::mut_from_ref)]
+    fn as_slice_mut(&self, lua: &RawLua) -> &mut [u8] {
+        unsafe {
+            let (buf, size) = self.as_raw_parts(lua);
+            std::slice::from_raw_parts_mut(buf, size)
+        }
     }
 
     #[cfg(feature = "luau")]
-    unsafe fn as_raw_parts(&self) -> (*mut u8, usize) {
-        let lua = self.0.lua.lock();
+    unsafe fn as_raw_parts(&self, lua: &RawLua) -> (*mut u8, usize) {
         let mut size = 0usize;
         let buf = ffi::lua_tobuffer(lua.ref_thread(), self.0.index, &mut size);
         mlua_assert!(!buf.is_null(), "invalid Luau buffer");
@@ -67,15 +88,76 @@ impl Buffer {
     }
 
     #[cfg(not(feature = "luau"))]
-    unsafe fn as_raw_parts(&self) -> (*mut u8, usize) {
+    unsafe fn as_raw_parts(&self, lua: &RawLua) -> (*mut u8, usize) {
         unreachable!()
     }
 }
 
+struct BufferCursor(Buffer, usize);
+
+impl io::Read for BufferCursor {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let lua = self.0 .0.lua.lock();
+        let data = self.0.as_slice(&lua);
+        if self.1 == data.len() {
+            return Ok(0);
+        }
+        let len = buf.len().min(data.len() - self.1);
+        buf[..len].copy_from_slice(&data[self.1..self.1 + len]);
+        self.1 += len;
+        Ok(len)
+    }
+}
+
+impl io::Write for BufferCursor {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        let lua = self.0 .0.lua.lock();
+        let data = self.0.as_slice_mut(&lua);
+        if self.1 == data.len() {
+            return Ok(0);
+        }
+        let len = buf.len().min(data.len() - self.1);
+        data[self.1..self.1 + len].copy_from_slice(&buf[..len]);
+        self.1 += len;
+        Ok(len)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+impl io::Seek for BufferCursor {
+    fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
+        let lua = self.0 .0.lua.lock();
+        let data = self.0.as_slice(&lua);
+        let new_offset = match pos {
+            io::SeekFrom::Start(offset) => offset as i64,
+            io::SeekFrom::End(offset) => data.len() as i64 + offset,
+            io::SeekFrom::Current(offset) => self.1 as i64 + offset,
+        };
+        if new_offset < 0 {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "invalid seek to a negative position",
+            ));
+        }
+        if new_offset as usize > data.len() {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "invalid seek to a position beyond the end of the buffer",
+            ));
+        }
+        self.1 = new_offset as usize;
+        Ok(self.1 as u64)
+    }
+}
+
 #[cfg(feature = "serde")]
 impl Serialize for Buffer {
     fn serialize<S: Serializer>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error> {
-        serializer.serialize_bytes(unsafe { self.as_slice() })
+        let lua = self.0.lua.lock();
+        serializer.serialize_bytes(self.as_slice(&lua))
     }
 }
 

src/chunk.rs

@@ -160,18 +160,39 @@ pub enum CompileConstant {
     Boolean(bool),
     Number(crate::Number),
     Vector(crate::Vector),
-    String(String),
+    String(StdString),
 }
 
-#[cfg(feature = "luau")]
-impl From<&'static str> for CompileConstant {
-    fn from(s: &'static str) -> Self {
-        CompileConstant::String(s.to_string())
+#[cfg(any(feature = "luau", doc))]
+impl From<bool> for CompileConstant {
+    fn from(b: bool) -> Self {
+        CompileConstant::Boolean(b)
     }
 }
 
 #[cfg(any(feature = "luau", doc))]
-type LibraryMemberConstantMap = std::sync::Arc<HashMap<(String, String), CompileConstant>>;
+impl From<crate::Number> for CompileConstant {
+    fn from(n: crate::Number) -> Self {
+        CompileConstant::Number(n)
+    }
+}
+
+#[cfg(any(feature = "luau", doc))]
+impl From<crate::Vector> for CompileConstant {
+    fn from(v: crate::Vector) -> Self {
+        CompileConstant::Vector(v)
+    }
+}
+
+#[cfg(any(feature = "luau", doc))]
+impl From<&str> for CompileConstant {
+    fn from(s: &str) -> Self {
+        CompileConstant::String(s.to_owned())
+    }
+}
+
+#[cfg(any(feature = "luau", doc))]
+type LibraryMemberConstantMap = HashMap<(StdString, StdString), CompileConstant>;
 
 /// Luau compiler
 #[cfg(any(feature = "luau", doc))]
@@ -182,14 +203,14 @@ pub struct Compiler {
     debug_level: u8,
     type_info_level: u8,
     coverage_level: u8,
-    vector_lib: Option<String>,
-    vector_ctor: Option<String>,
-    vector_type: Option<String>,
-    mutable_globals: Vec<String>,
-    userdata_types: Vec<String>,
-    libraries_with_known_members: Vec<String>,
+    vector_lib: Option<StdString>,
+    vector_ctor: Option<StdString>,
+    vector_type: Option<StdString>,
+    mutable_globals: Vec<StdString>,
+    userdata_types: Vec<StdString>,
+    libraries_with_known_members: Vec<StdString>,
     library_constants: Option<LibraryMemberConstantMap>,
-    disabled_builtins: Vec<String>,
+    disabled_builtins: Vec<StdString>,
 }
 
 #[cfg(any(feature = "luau", doc))]
@@ -267,70 +288,102 @@ impl Compiler {
         self
     }
 
+    /// Sets alternative global builtin to construct vectors, in addition to default builtin
+    /// `vector.create`.
+    ///
+    /// To set the library and method name, use the `lib.ctor` format.
     #[doc(hidden)]
     #[must_use]
-    pub fn set_vector_lib(mut self, lib: impl Into<String>) -> Self {
-        self.vector_lib = Some(lib.into());
+    pub fn set_vector_ctor(mut self, ctor: impl Into<StdString>) -> Self {
+        let ctor = ctor.into();
+        let lib_ctor = ctor.split_once('.');
+        self.vector_lib = lib_ctor.as_ref().map(|&(lib, _)| lib.to_owned());
+        self.vector_ctor = (lib_ctor.as_ref())
+            .map(|&(_, ctor)| ctor.to_owned())
+            .or(Some(ctor));
         self
     }
 
+    /// Sets alternative vector type name for type tables, in addition to default type `vector`.
     #[doc(hidden)]
     #[must_use]
-    pub fn set_vector_ctor(mut self, ctor: impl Into<String>) -> Self {
-        self.vector_ctor = Some(ctor.into());
-        self
-    }
-
-    #[doc(hidden)]
-    #[must_use]
-    pub fn set_vector_type(mut self, r#type: impl Into<String>) -> Self {
+    pub fn set_vector_type(mut self, r#type: impl Into<StdString>) -> Self {
         self.vector_type = Some(r#type.into());
         self
     }
 
+    /// Adds a mutable global.
+    ///
+    /// It disables the import optimization for fields accessed through it.
+    #[must_use]
+    pub fn add_mutable_global(mut self, global: impl Into<StdString>) -> Self {
+        self.mutable_globals.push(global.into());
+        self
+    }
+
     /// Sets a list of globals that are mutable.
     ///
     /// It disables the import optimization for fields accessed through these.
     #[must_use]
-    pub fn set_mutable_globals<S: Into<String>>(mut self, globals: Vec<S>) -> Self {
+    pub fn set_mutable_globals<S: Into<StdString>>(mut self, globals: impl IntoIterator<Item = S>) -> Self {
         self.mutable_globals = globals.into_iter().map(|s| s.into()).collect();
         self
     }
 
+    /// Adds a userdata type to the list that will be included in the type information.
+    #[must_use]
+    pub fn add_userdata_type(mut self, r#type: impl Into<StdString>) -> Self {
+        self.userdata_types.push(r#type.into());
+        self
+    }
+
     /// Sets a list of userdata types that will be included in the type information.
     #[must_use]
-    pub fn set_userdata_types<S: Into<String>>(mut self, types: Vec<S>) -> Self {
+    pub fn set_userdata_types<S: Into<StdString>>(mut self, types: impl IntoIterator<Item = S>) -> Self {
         self.userdata_types = types.into_iter().map(|s| s.into()).collect();
         self
     }
 
-    /// Sets constants for known library members.
+    /// Adds a constant for a known library member.
     ///
     /// The constants are used by the compiler to optimize the generated bytecode.
     /// Optimization level must be at least 2 for this to have any effect.
     ///
-    /// The first element of the tuple is the library name,the second is the member name, and the
-    /// third is the constant value.
+    /// The `name` is a string in the format `lib.member`, where `lib` is the library name
+    /// and `member` is the member (constant) name.
     #[must_use]
-    pub fn set_library_constants<L, M>(mut self, constants: Vec<(L, M, CompileConstant)>) -> Self
-    where
-        L: Into<String>,
-        M: Into<String>,
-    {
-        let map = constants
-            .into_iter()
-            .map(|(lib, member, cons)| ((lib.into(), member.into()), cons))
-            .collect::<HashMap<_, _>>();
-        self.library_constants = Some(std::sync::Arc::new(map));
-        self.libraries_with_known_members = (self.library_constants.clone())
-            .map(|map| map.keys().map(|(lib, _)| lib.clone()).collect())
-            .unwrap_or_default();
+    pub fn add_library_constant(
+        mut self,
+        name: impl AsRef<str>,
+        r#const: impl Into<CompileConstant>,
+    ) -> Self {
+        let Some((lib, member)) = name.as_ref().split_once('.') else {
+            return self;
+        };
+        let (lib, member) = (lib.to_owned(), member.to_owned());
+
+        if !self.libraries_with_known_members.contains(&lib) {
+            self.libraries_with_known_members.push(lib.clone());
+        }
+        self.library_constants
+            .get_or_insert_with(HashMap::new)
+            .insert((lib, member), r#const.into());
+        self
+    }
+
+    /// Adds a builtin that should be disabled.
+    #[must_use]
+    pub fn add_disabled_builtin(mut self, builtin: impl Into<StdString>) -> Self {
+        self.disabled_builtins.push(builtin.into());
         self
     }
 
     /// Sets a list of builtins that should be disabled.
     #[must_use]
-    pub fn set_disabled_builtins<S: Into<String>>(mut self, builtins: Vec<S>) -> Self {
+    pub fn set_disabled_builtins<S: Into<StdString>>(
+        mut self,
+        builtins: impl IntoIterator<Item = S>,
+    ) -> Self {
         self.disabled_builtins = builtins.into_iter().map(|s| s.into()).collect();
         self
     }
@@ -437,7 +490,7 @@ impl Compiler {
         if bytecode.first() == Some(&0) {
             // The rest of the bytecode is the error message starting with `:`
             // See https://github.com/luau-lang/luau/blob/0.640/Compiler/src/Compiler.cpp#L4336
-            let message = String::from_utf8_lossy(&bytecode[2..]).to_string();
+            let message = StdString::from_utf8_lossy(&bytecode[2..]).into_owned();
             return Err(Error::SyntaxError {
                 incomplete_input: message.ends_with("<eof>"),
                 message,
@@ -460,7 +513,7 @@ impl Chunk<'_> {
     /// - `@` - file path (when truncation is needed, the end of the file path is kept, as this is
     ///   more useful for identifying the file)
     /// - `=` - custom chunk name (when truncation is needed, the beginning of the name is kept)
-    pub fn set_name(mut self, name: impl Into<String>) -> Self {
+    pub fn set_name(mut self, name: impl Into<StdString>) -> Self {
         self.name = name.into();
         self
     }
@@ -708,7 +761,7 @@ impl Chunk<'_> {
         ChunkMode::Text
     }
 
-    fn convert_name(name: String) -> Result<CString> {
+    fn convert_name(name: StdString) -> Result<CString> {
         CString::new(name).map_err(|err| Error::runtime(format!("invalid name: {err}")))
     }
 

src/conversion.rs

@@ -500,11 +500,21 @@ impl FromLua for crate::Buffer {
 impl IntoLua for StdString {
     #[inline]
     fn into_lua(self, lua: &Lua) -> Result<Value> {
+        #[cfg(feature = "lua55")]
+        if true {
+            return Ok(Value::String(lua.create_external_string(self)?));
+        }
+
         Ok(Value::String(lua.create_string(self)?))
     }
 
     #[inline]
     unsafe fn push_into_stack(self, lua: &RawLua) -> Result<()> {
+        #[cfg(feature = "lua55")]
+        if lua.unlikely_memory_error() {
+            return crate::util::push_external_string(lua.state(), self.into(), false);
+        }
+
         push_bytes_into_stack(self, lua)
     }
 }
@@ -591,6 +601,11 @@ impl FromLua for Box<str> {
 impl IntoLua for CString {
     #[inline]
     fn into_lua(self, lua: &Lua) -> Result<Value> {
+        #[cfg(feature = "lua55")]
+        if true {
+            return Ok(Value::String(lua.create_external_string(self)?));
+        }
+
         Ok(Value::String(lua.create_string(self.as_bytes())?))
     }
 }
@@ -635,6 +650,11 @@ impl IntoLua for Cow<'_, CStr> {
 impl IntoLua for BString {
     #[inline]
     fn into_lua(self, lua: &Lua) -> Result<Value> {
+        #[cfg(feature = "lua55")]
+        if true {
+            return Ok(Value::String(lua.create_external_string(self)?));
+        }
+
         Ok(Value::String(lua.create_string(self)?))
     }
 }
@@ -645,7 +665,7 @@ impl FromLua for BString {
         match value {
             Value::String(s) => Ok((*s.as_bytes()).into()),
             #[cfg(feature = "luau")]
-            Value::Buffer(buf) => unsafe { Ok(buf.as_slice().into()) },
+            Value::Buffer(buf) => Ok(buf.to_vec().into()),
             _ => Ok((*lua
                 .coerce_string(value)?
                 .ok_or_else(|| Error::FromLuaConversionError {
@@ -1191,7 +1211,8 @@ impl<L: FromLua, R: FromLua> FromLua for Either<L, R> {
             Err(_) => match R::from_stack(idx, lua).map(Either::Right) {
                 Ok(r) => Ok(r),
                 Err(_) => {
-                    let value_type_name = CStr::from_ptr(ffi::luaL_typename(lua.state(), idx));
+                    let value_type_name =
+                        CStr::from_ptr(ffi::lua_typename(lua.state(), ffi::lua_type(lua.state(), idx)));
                     Err(Error::FromLuaConversionError {
                         from: value_type_name.to_str().unwrap(),
                         to: Self::type_name(),

src/debug.rs

@@ -1,66 +1,33 @@
 use std::borrow::Cow;
-use std::cell::UnsafeCell;
-use std::ops::Deref;
-#[cfg(not(feature = "luau"))]
-use std::ops::{BitOr, BitOrAssign};
 use std::os::raw::c_int;
 
-use ffi::lua_Debug;
+use ffi::{lua_Debug, lua_State};
 
+use crate::function::Function;
 use crate::state::RawLua;
-use crate::types::ReentrantMutexGuard;
-use crate::util::{linenumber_to_usize, ptr_to_lossy_str, ptr_to_str};
+use crate::util::{assert_stack, linenumber_to_usize, ptr_to_lossy_str, ptr_to_str, StackGuard};
 
 /// 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 [documentation].
+/// You may call the methods on this structure to retrieve information about the Lua code executing
+/// at the specific level. Further information can be found in the Lua [documentation].
 ///
 /// [documentation]: https://www.lua.org/manual/5.4/manual.html#lua_Debug
-/// [`Lua::set_hook`]: crate::Lua::set_hook
 pub struct Debug<'a> {
-    lua: EitherLua<'a>,
-    ar: ActivationRecord,
-    #[cfg(feature = "luau")]
+    state: *mut lua_State,
+    lua: &'a RawLua,
+    #[cfg_attr(not(feature = "luau"), allow(unused))]
     level: c_int,
-}
-
-enum EitherLua<'a> {
-    Owned(ReentrantMutexGuard<'a, RawLua>),
-    #[cfg(not(feature = "luau"))]
-    Borrowed(&'a RawLua),
-}
-
-impl Deref for EitherLua<'_> {
-    type Target = RawLua;
-
-    fn deref(&self) -> &Self::Target {
-        match self {
-            EitherLua::Owned(guard) => guard,
-            #[cfg(not(feature = "luau"))]
-            EitherLua::Borrowed(lua) => lua,
-        }
-    }
+    ar: *mut lua_Debug,
 }
 
 impl<'a> Debug<'a> {
-    // We assume the lock is held when this function is called.
-    #[cfg(not(feature = "luau"))]
-    pub(crate) fn new(lua: &'a RawLua, ar: *mut lua_Debug) -> Self {
+    pub(crate) fn new(lua: &'a RawLua, level: c_int, ar: *mut lua_Debug) -> Self {
         Debug {
-            lua: EitherLua::Borrowed(lua),
-            ar: ActivationRecord::Borrowed(ar),
-        }
-    }
-
-    pub(crate) fn new_owned(guard: ReentrantMutexGuard<'a, RawLua>, _level: c_int, ar: lua_Debug) -> Self {
-        Debug {
-            lua: EitherLua::Owned(guard),
-            ar: ActivationRecord::Owned(UnsafeCell::new(ar)),
-            #[cfg(feature = "luau")]
-            level: _level,
+            state: lua.state(),
+            lua,
+            ar,
+            level,
         }
     }
 
@@ -74,7 +41,7 @@ impl<'a> Debug<'a> {
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn event(&self) -> DebugEvent {
         unsafe {
-            match (*self.ar.get()).event {
+            match (*self.ar).event {
                 ffi::LUA_HOOKCALL => DebugEvent::Call,
                 ffi::LUA_HOOKRET => DebugEvent::Ret,
                 ffi::LUA_HOOKTAILCALL => DebugEvent::TailCall,
@@ -85,24 +52,48 @@ impl<'a> Debug<'a> {
         }
     }
 
-    /// Corresponds to the `n` what mask.
-    pub fn names(&self) -> DebugNames {
+    /// Returns the function that is running at the given level.
+    ///
+    /// Corresponds to the `f` "what" mask.
+    pub fn function(&self) -> Function {
+        unsafe {
+            let _sg = StackGuard::new(self.state);
+            assert_stack(self.state, 1);
+
+            #[cfg(not(feature = "luau"))]
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, cstr!("f"), self.ar) != 0,
+                "lua_getinfo failed with `f`"
+            );
+            #[cfg(feature = "luau")]
+            mlua_assert!(
+                ffi::lua_getinfo(self.state, self.level, cstr!("f"), self.ar) != 0,
+                "lua_getinfo failed with `f`"
+            );
+
+            ffi::lua_xmove(self.state, self.lua.ref_thread(), 1);
+            Function(self.lua.pop_ref_thread())
+        }
+    }
+
+    /// Corresponds to the `n` "what" mask.
+    pub fn names(&self) -> DebugNames<'_> {
         unsafe {
             #[cfg(not(feature = "luau"))]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), cstr!("n"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, cstr!("n"), self.ar) != 0,
                 "lua_getinfo failed with `n`"
             );
             #[cfg(feature = "luau")]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), self.level, cstr!("n"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, self.level, cstr!("n"), self.ar) != 0,
                 "lua_getinfo failed with `n`"
             );
 
             DebugNames {
-                name: ptr_to_lossy_str((*self.ar.get()).name),
+                name: ptr_to_lossy_str((*self.ar).name),
                 #[cfg(not(feature = "luau"))]
-                name_what: match ptr_to_str((*self.ar.get()).namewhat) {
+                name_what: match ptr_to_str((*self.ar).namewhat) {
                     Some("") => None,
                     val => val,
                 },
@@ -112,118 +103,110 @@ impl<'a> Debug<'a> {
         }
     }
 
-    /// Corresponds to the `S` what mask.
-    pub fn source(&self) -> DebugSource {
+    /// Corresponds to the `S` "what" mask.
+    pub fn source(&self) -> DebugSource<'_> {
         unsafe {
             #[cfg(not(feature = "luau"))]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), cstr!("S"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, cstr!("S"), self.ar) != 0,
                 "lua_getinfo failed with `S`"
             );
             #[cfg(feature = "luau")]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), self.level, cstr!("s"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, self.level, cstr!("s"), self.ar) != 0,
                 "lua_getinfo failed with `s`"
             );
 
             DebugSource {
-                source: ptr_to_lossy_str((*self.ar.get()).source),
+                source: ptr_to_lossy_str((*self.ar).source),
                 #[cfg(not(feature = "luau"))]
-                short_src: ptr_to_lossy_str((*self.ar.get()).short_src.as_ptr()),
+                short_src: ptr_to_lossy_str((*self.ar).short_src.as_ptr()),
                 #[cfg(feature = "luau")]
-                short_src: ptr_to_lossy_str((*self.ar.get()).short_src),
-                line_defined: linenumber_to_usize((*self.ar.get()).linedefined),
+                short_src: ptr_to_lossy_str((*self.ar).short_src),
+                line_defined: linenumber_to_usize((*self.ar).linedefined),
                 #[cfg(not(feature = "luau"))]
-                last_line_defined: linenumber_to_usize((*self.ar.get()).lastlinedefined),
+                last_line_defined: linenumber_to_usize((*self.ar).lastlinedefined),
                 #[cfg(feature = "luau")]
                 last_line_defined: None,
-                what: ptr_to_str((*self.ar.get()).what).unwrap_or("main"),
+                what: ptr_to_str((*self.ar).what).unwrap_or("main"),
             }
         }
     }
 
-    /// Corresponds to the `l` what mask. Returns the current line.
+    #[doc(hidden)]
+    #[deprecated(note = "Use `current_line` instead")]
     pub fn curr_line(&self) -> i32 {
+        self.current_line().map(|n| n as i32).unwrap_or(-1)
+    }
+
+    /// Corresponds to the `l` "what" mask. Returns the current line.
+    pub fn current_line(&self) -> Option<usize> {
         unsafe {
             #[cfg(not(feature = "luau"))]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), cstr!("l"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, cstr!("l"), self.ar) != 0,
                 "lua_getinfo failed with `l`"
             );
             #[cfg(feature = "luau")]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), self.level, cstr!("l"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, self.level, cstr!("l"), self.ar) != 0,
                 "lua_getinfo failed with `l`"
             );
 
-            (*self.ar.get()).currentline
+            linenumber_to_usize((*self.ar).currentline)
         }
     }
 
-    /// Corresponds to the `t` what mask. Returns true if the hook is in a function tail call, false
-    /// otherwise.
-    #[cfg(not(feature = "luau"))]
-    #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
+    /// Corresponds to the `t` "what" mask. Returns true if the hook is in a function tail call,
+    /// false otherwise.
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52")))
+    )]
     pub fn is_tail_call(&self) -> bool {
         unsafe {
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), cstr!("t"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, cstr!("t"), self.ar) != 0,
                 "lua_getinfo failed with `t`"
             );
-            (*self.ar.get()).currentline != 0
+            (*self.ar).istailcall != 0
         }
     }
 
-    /// Corresponds to the `u` what mask.
+    /// Corresponds to the `u` "what" mask.
     pub fn stack(&self) -> DebugStack {
         unsafe {
             #[cfg(not(feature = "luau"))]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), cstr!("u"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, cstr!("u"), self.ar) != 0,
                 "lua_getinfo failed with `u`"
             );
             #[cfg(feature = "luau")]
             mlua_assert!(
-                ffi::lua_getinfo(self.lua.state(), self.level, cstr!("au"), self.ar.get()) != 0,
+                ffi::lua_getinfo(self.state, self.level, cstr!("au"), self.ar) != 0,
                 "lua_getinfo failed with `au`"
             );
 
             #[cfg(not(feature = "luau"))]
             let stack = DebugStack {
-                num_ups: (*self.ar.get()).nups as _,
-                #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
-                num_params: (*self.ar.get()).nparams as _,
-                #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
-                is_vararg: (*self.ar.get()).isvararg != 0,
+                num_ups: (*self.ar).nups as _,
+                #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
+                num_params: (*self.ar).nparams as _,
+                #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
+                is_vararg: (*self.ar).isvararg != 0,
             };
             #[cfg(feature = "luau")]
             let stack = DebugStack {
-                num_ups: (*self.ar.get()).nupvals,
-                num_params: (*self.ar.get()).nparams,
-                is_vararg: (*self.ar.get()).isvararg != 0,
+                num_ups: (*self.ar).nupvals,
+                num_params: (*self.ar).nparams,
+                is_vararg: (*self.ar).isvararg != 0,
             };
             stack
         }
     }
 }
 
-enum ActivationRecord {
-    #[cfg(not(feature = "luau"))]
-    Borrowed(*mut lua_Debug),
-    Owned(UnsafeCell<lua_Debug>),
-}
-
-impl ActivationRecord {
-    #[inline]
-    fn get(&self) -> *mut lua_Debug {
-        match self {
-            #[cfg(not(feature = "luau"))]
-            ActivationRecord::Borrowed(x) => *x,
-            ActivationRecord::Owned(x) => x.get(),
-        }
-    }
-}
-
 /// Represents a specific event that triggered the hook.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum DebugEvent {
@@ -265,17 +248,41 @@ pub struct DebugStack {
     /// Number of upvalues.
     pub num_ups: u8,
     /// Number of parameters.
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau"))]
+    #[cfg(any(
+        feature = "lua55",
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luau"
+    ))]
     #[cfg_attr(
         docsrs,
-        doc(cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau")))
+        doc(cfg(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "luau"
+        )))
     )]
     pub num_params: u8,
     /// Whether the function is a vararg function.
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau"))]
+    #[cfg(any(
+        feature = "lua55",
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luau"
+    ))]
     #[cfg_attr(
         docsrs,
-        doc(cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau")))
+        doc(cfg(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "luau"
+        )))
     )]
     pub is_vararg: bool,
 }
@@ -382,7 +389,7 @@ impl HookTriggers {
 }
 
 #[cfg(not(feature = "luau"))]
-impl BitOr for HookTriggers {
+impl std::ops::BitOr for HookTriggers {
     type Output = Self;
 
     fn bitor(mut self, rhs: Self) -> Self::Output {
@@ -397,7 +404,7 @@ impl BitOr for HookTriggers {
 }
 
 #[cfg(not(feature = "luau"))]
-impl BitOrAssign for HookTriggers {
+impl std::ops::BitOrAssign for HookTriggers {
     fn bitor_assign(&mut self, rhs: Self) {
         *self = *self | rhs;
     }

src/function.rs

@@ -18,7 +18,7 @@ use {
     crate::traits::LuaNativeAsyncFn,
     crate::types::AsyncCallback,
     std::future::{self, Future},
-    std::pin::Pin,
+    std::pin::{pin, Pin},
     std::task::{Context, Poll},
 };
 
@@ -32,6 +32,7 @@ pub struct Function(pub(crate) ValueRef);
 ///
 /// [`Lua Debug Interface`]: https://www.lua.org/manual/5.4/manual.html#4.7
 #[derive(Clone, Debug)]
+#[non_exhaustive]
 pub struct FunctionInfo {
     /// A (reasonable) name of the function (`None` if the name cannot be found).
     pub name: Option<String>,
@@ -50,6 +51,16 @@ pub struct FunctionInfo {
     pub line_defined: Option<usize>,
     /// The line number where the definition of the function ends (not set by Luau).
     pub last_line_defined: Option<usize>,
+    /// The number of upvalues of the function.
+    pub num_upvalues: u8,
+    /// The number of parameters of the function (always 0 for C).
+    #[cfg(any(not(any(feature = "lua51", feature = "luajit")), doc))]
+    #[cfg_attr(docsrs, doc(cfg(not(any(feature = "lua51", feature = "luajit")))))]
+    pub num_params: u8,
+    /// Whether the function is a variadic function (always true for C).
+    #[cfg(any(not(any(feature = "lua51", feature = "luajit")), doc))]
+    #[cfg_attr(docsrs, doc(cfg(not(any(feature = "lua51", feature = "luajit")))))]
+    pub is_vararg: bool,
 }
 
 /// Luau function coverage snapshot.
@@ -276,7 +287,7 @@ impl Function {
 
             #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
             ffi::lua_getfenv(state, -1);
-            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
             for i in 1..=255 {
                 // Traverse upvalues until we find the _ENV one
                 match ffi::lua_getupvalue(state, -1, i) {
@@ -316,7 +327,7 @@ impl Function {
                 lua.push_ref(&env.0);
                 ffi::lua_setfenv(state, -2);
             }
-            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
             for i in 1..=255 {
                 match ffi::lua_getupvalue(state, -1, i) {
                     s if s.is_null() => return Ok(false),
@@ -343,7 +354,8 @@ impl Function {
 
     /// Returns information about the function.
     ///
-    /// Corresponds to the `>Sn` what mask for [`lua_getinfo`] when applied to the function.
+    /// Corresponds to the `>Snu` (`>Sn` for Luau) what mask for
+    /// [`lua_getinfo`] when applied to the function.
     ///
     /// [`lua_getinfo`]: https://www.lua.org/manual/5.4/manual.html#lua_getinfo
     pub fn info(&self) -> FunctionInfo {
@@ -355,11 +367,16 @@ impl Function {
 
             let mut ar: ffi::lua_Debug = mem::zeroed();
             lua.push_ref(&self.0);
+
             #[cfg(not(feature = "luau"))]
-            let res = ffi::lua_getinfo(state, cstr!(">Sn"), &mut ar);
+            let res = ffi::lua_getinfo(state, cstr!(">Snu"), &mut ar);
+            #[cfg(not(feature = "luau"))]
+            mlua_assert!(res != 0, "lua_getinfo failed with `>Snu`");
+
             #[cfg(feature = "luau")]
-            let res = ffi::lua_getinfo(state, -1, cstr!("sn"), &mut ar);
-            mlua_assert!(res != 0, "lua_getinfo failed with `>Sn`");
+            let res = ffi::lua_getinfo(state, -1, cstr!("snau"), &mut ar);
+            #[cfg(feature = "luau")]
+            mlua_assert!(res != 0, "lua_getinfo failed with `snau`");
 
             FunctionInfo {
                 name: ptr_to_lossy_str(ar.name).map(|s| s.into_owned()),
@@ -381,6 +398,14 @@ impl Function {
                 last_line_defined: linenumber_to_usize(ar.lastlinedefined),
                 #[cfg(feature = "luau")]
                 last_line_defined: None,
+                #[cfg(not(feature = "luau"))]
+                num_upvalues: ar.nups as _,
+                #[cfg(feature = "luau")]
+                num_upvalues: ar.nupvals,
+                #[cfg(not(any(feature = "lua51", feature = "luajit")))]
+                num_params: ar.nparams,
+                #[cfg(not(any(feature = "lua51", feature = "luajit")))]
+                is_vararg: ar.isvararg != 0,
             }
         }
     }
@@ -400,11 +425,14 @@ impl Function {
             _state: *mut ffi::lua_State,
             buf: *const c_void,
             buf_len: usize,
-            data: *mut c_void,
+            data_ptr: *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);
+            // If `data` is null, then it's a signal that write is finished.
+            if !data_ptr.is_null() && buf_len > 0 {
+                let data = &mut *(data_ptr as *mut Vec<u8>);
+                let buf = slice::from_raw_parts(buf as *const u8, buf_len);
+                data.extend_from_slice(buf);
+            }
             0
         }
 
@@ -434,7 +462,7 @@ impl Function {
     /// [`Compiler::set_coverage_level`]: crate::chunk::Compiler::set_coverage_level
     #[cfg(any(feature = "luau", doc))]
     #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
-    pub fn coverage<F>(&self, mut func: F)
+    pub fn coverage<F>(&self, func: F)
     where
         F: FnMut(CoverageInfo),
     {
@@ -454,13 +482,16 @@ impl Function {
             } else {
                 None
             };
-            let rust_callback = &mut *(data as *mut F);
-            rust_callback(CoverageInfo {
-                function,
-                line_defined,
-                depth,
-                hits: slice::from_raw_parts(hits, size).to_vec(),
-            });
+            let rust_callback = &*(data as *const RefCell<F>);
+            if let Ok(mut rust_callback) = rust_callback.try_borrow_mut() {
+                // Call the Rust callback with CoverageInfo
+                rust_callback(CoverageInfo {
+                    function,
+                    line_defined,
+                    depth,
+                    hits: slice::from_raw_parts(hits, size).to_vec(),
+                });
+            }
         }
 
         let lua = self.0.lua.lock();
@@ -470,7 +501,8 @@ impl Function {
             assert_stack(state, 1);
 
             lua.push_ref(&self.0);
-            let func_ptr = &mut func as *mut F as *mut c_void;
+            let func = RefCell::new(func);
+            let func_ptr = &func as *const RefCell<F> as *mut c_void;
             ffi::lua_getcoverage(state, -1, func_ptr, callback::<F>);
         }
     }
@@ -492,16 +524,24 @@ impl Function {
     /// This function returns shallow clone (same handle) for Rust/C functions.
     #[cfg(any(feature = "luau", doc))]
     #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
-    pub fn deep_clone(&self) -> Self {
+    pub fn deep_clone(&self) -> Result<Self> {
         let lua = self.0.lua.lock();
-        let ref_thread = lua.ref_thread();
+        let state = lua.state();
         unsafe {
-            if ffi::lua_iscfunction(ref_thread, self.0.index) != 0 {
-                return self.clone();
+            let _sg = StackGuard::new(state);
+            check_stack(state, 2)?;
+
+            lua.push_ref(&self.0);
+            if ffi::lua_iscfunction(state, -1) != 0 {
+                return Ok(self.clone());
             }
 
-            ffi::lua_clonefunction(ref_thread, self.0.index);
-            Function(lua.pop_ref_thread())
+            if lua.unlikely_memory_error() {
+                ffi::lua_clonefunction(state, -1);
+            } else {
+                protect_lua!(state, 1, 1, fn(state) ffi::lua_clonefunction(state, -1))?;
+            }
+            Ok(Function(lua.pop_ref()))
         }
     }
 }
@@ -645,18 +685,21 @@ impl LuaType for Function {
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct AsyncCallFuture<R: FromLuaMulti>(Result<AsyncThread<R>>);
 
+#[cfg(feature = "async")]
+impl<R: FromLuaMulti> AsyncCallFuture<R> {
+    pub(crate) fn error(err: Error) -> Self {
+        AsyncCallFuture(Err(err))
+    }
+}
+
 #[cfg(feature = "async")]
 impl<R: FromLuaMulti> Future for AsyncCallFuture<R> {
     type Output = Result<R>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        // Safety: We're not moving any pinned data
-        let this = unsafe { self.get_unchecked_mut() };
+        let this = self.get_mut();
         match &mut this.0 {
-            Ok(thread) => {
-                let pinned_thread = unsafe { Pin::new_unchecked(thread) };
-                pinned_thread.poll(cx)
-            }
+            Ok(thread) => pin!(thread).poll(cx),
             Err(err) => Poll::Ready(Err(err.clone())),
         }
     }

src/lib.rs

@@ -75,9 +75,9 @@ mod macros;
 mod buffer;
 mod chunk;
 mod conversion;
+mod debug;
 mod error;
 mod function;
-mod hook;
 #[cfg(any(feature = "luau", doc))]
 mod luau;
 mod memory;
@@ -101,9 +101,9 @@ pub use bstr::BString;
 pub use ffi::{self, lua_CFunction, lua_State};
 
 pub use crate::chunk::{AsChunk, Chunk, ChunkMode};
+pub use crate::debug::{Debug, DebugEvent, DebugNames, DebugSource, DebugStack};
 pub use crate::error::{Error, ErrorContext, ExternalError, ExternalResult, Result};
 pub use crate::function::{Function, FunctionInfo};
-pub use crate::hook::{Debug, DebugEvent, DebugNames, DebugSource, DebugStack};
 pub use crate::multi::{MultiValue, Variadic};
 pub use crate::scope::Scope;
 pub use crate::state::{GCMode, Lua, LuaOptions, WeakLua};
@@ -124,7 +124,7 @@ pub use crate::userdata::{
 pub use crate::value::{Nil, Value};
 
 #[cfg(not(feature = "luau"))]
-pub use crate::hook::HookTriggers;
+pub use crate::debug::HookTriggers;
 
 #[cfg(any(feature = "luau", doc))]
 #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
@@ -132,7 +132,7 @@ pub use crate::{
     buffer::Buffer,
     chunk::{CompileConstant, Compiler},
     function::CoverageInfo,
-    luau::{NavigateError, Require, TextRequirer},
+    luau::{HeapDump, NavigateError, Require, TextRequirer},
     vector::Vector,
 };
 
@@ -142,7 +142,10 @@ pub use crate::{thread::AsyncThread, traits::LuaNativeAsyncFn};
 
 #[cfg(feature = "serde")]
 #[doc(inline)]
-pub use crate::serde::{de::Options as DeserializeOptions, ser::Options as SerializeOptions, LuaSerdeExt};
+pub use crate::{
+    serde::{de::Options as DeserializeOptions, ser::Options as SerializeOptions, LuaSerdeExt},
+    value::SerializableValue,
+};
 
 #[cfg(feature = "serde")]
 #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]

src/luau/heap_dump.rs

@@ -0,0 +1,178 @@
+use std::collections::HashMap;
+use std::hash::Hash;
+use std::mem;
+use std::os::raw::c_char;
+
+use crate::state::ExtraData;
+
+use super::json::{self, Json};
+
+/// Represents a heap dump of a Luau memory state.
+#[cfg(any(feature = "luau", doc))]
+#[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+pub struct HeapDump {
+    data: Json<'static>, // refers to the contents of `buf`
+    buf: Box<str>,
+}
+
+impl HeapDump {
+    /// Dumps the current Lua heap state.
+    pub(crate) unsafe fn new(state: *mut ffi::lua_State) -> Option<Self> {
+        unsafe extern "C" fn category_name(state: *mut ffi::lua_State, cat: u8) -> *const c_char {
+            (&*ExtraData::get(state))
+                .mem_categories
+                .get(cat as usize)
+                .map(|s| s.as_ptr())
+                .unwrap_or(cstr!("unknown"))
+        }
+
+        let mut buf = Vec::new();
+        unsafe {
+            let file = libc::tmpfile();
+            if file.is_null() {
+                return None;
+            }
+            ffi::lua_gcdump(state, file as *mut _, Some(category_name));
+            libc::fseek(file, 0, libc::SEEK_END);
+            let len = libc::ftell(file) as usize;
+            libc::rewind(file);
+            if len > 0 {
+                buf.reserve(len);
+                libc::fread(buf.as_mut_ptr() as *mut _, 1, len, file);
+                buf.set_len(len);
+            }
+            libc::fclose(file);
+        }
+
+        let buf = String::from_utf8(buf).ok()?.into_boxed_str();
+        let data = json::parse(unsafe { mem::transmute::<&str, &'static str>(&buf) }).ok()?;
+        Some(HeapDump { data, buf })
+    }
+
+    /// Returns the raw JSON representation of the heap dump.
+    ///
+    /// The JSON structure is an internal detail and may change in future versions.
+    #[doc(hidden)]
+    pub fn to_json(&self) -> &str {
+        &self.buf
+    }
+
+    /// Returns the total size of the Lua heap in bytes.
+    pub fn size(&self) -> u64 {
+        self.data["stats"]["size"].as_u64().unwrap_or_default()
+    }
+
+    /// Returns a mapping from object type to (count, total size in bytes).
+    ///
+    /// If `category` is provided, only objects in that category are considered.
+    pub fn size_by_type<'a>(&'a self, category: Option<&str>) -> HashMap<&'a str, (usize, u64)> {
+        self.size_by_type_inner(category).unwrap_or_default()
+    }
+
+    fn size_by_type_inner<'a>(&'a self, category: Option<&str>) -> Option<HashMap<&'a str, (usize, u64)>> {
+        let category_id = match category {
+            // If we cannot find the category, return empty result
+            Some(cat) => Some(self.find_category_id(cat)?),
+            None => None,
+        };
+
+        let mut size_by_type = HashMap::new();
+        let objects = self.data["objects"].as_object()?;
+        for obj in objects.values() {
+            if let Some(cat_id) = category_id {
+                if obj["cat"].as_i64()? != cat_id {
+                    continue;
+                }
+            }
+            update_size(&mut size_by_type, obj["type"].as_str()?, obj["size"].as_u64()?);
+        }
+        Some(size_by_type)
+    }
+
+    /// Returns a mapping from category name to total size in bytes.
+    pub fn size_by_category(&self) -> HashMap<&str, u64> {
+        let mut size_by_category = HashMap::new();
+        if let Some(categories) = self.data["stats"]["categories"].as_object() {
+            for cat in categories.values() {
+                if let Some(cat_name) = cat["name"].as_str() {
+                    size_by_category.insert(cat_name, cat["size"].as_u64().unwrap_or_default());
+                }
+            }
+        }
+        size_by_category
+    }
+
+    /// Returns a mapping from userdata type to (count, total size in bytes).
+    pub fn size_by_userdata<'a>(&'a self, category: Option<&str>) -> HashMap<&'a str, (usize, u64)> {
+        self.size_by_userdata_inner(category).unwrap_or_default()
+    }
+
+    fn size_by_userdata_inner<'a>(
+        &'a self,
+        category: Option<&str>,
+    ) -> Option<HashMap<&'a str, (usize, u64)>> {
+        let category_id = match category {
+            // If we cannot find the category, return empty result
+            Some(cat) => Some(self.find_category_id(cat)?),
+            None => None,
+        };
+
+        let mut size_by_userdata = HashMap::new();
+        let objects = self.data["objects"].as_object()?;
+        for obj in objects.values() {
+            if obj["type"] != "userdata" {
+                continue;
+            }
+            if let Some(cat_id) = category_id {
+                if obj["cat"].as_i64()? != cat_id {
+                    continue;
+                }
+            }
+
+            // Determine userdata type from metatable
+            let mut ud_type = "unknown";
+            if let Some(metatable_addr) = obj["metatable"].as_str() {
+                if let Some(t) = get_key(objects, &objects[metatable_addr], "__type") {
+                    ud_type = t;
+                }
+            }
+            update_size(&mut size_by_userdata, ud_type, obj["size"].as_u64()?);
+        }
+        Some(size_by_userdata)
+    }
+
+    /// Finds the category ID for a given category name.
+    fn find_category_id(&self, category: &str) -> Option<i64> {
+        let categories = self.data["stats"]["categories"].as_object()?;
+        for (cat_id, cat) in categories {
+            if cat["name"].as_str() == Some(category) {
+                return cat_id.parse().ok();
+            }
+        }
+        None
+    }
+}
+
+/// Updates the size mapping for a given key.
+fn update_size<K: Eq + Hash>(size_type: &mut HashMap<K, (usize, u64)>, key: K, size: u64) {
+    let (ref mut count, ref mut total_size) = size_type.entry(key).or_insert((0, 0));
+    *count += 1;
+    *total_size += size;
+}
+
+/// Retrieves the value associated with a given `key` from a Lua table `tbl`.
+fn get_key<'a>(objects: &'a HashMap<&'a str, Json>, tbl: &Json, key: &str) -> Option<&'a str> {
+    let pairs = tbl["pairs"].as_array()?;
+    for kv in pairs.chunks_exact(2) {
+        #[rustfmt::skip]
+        let (Some(key_addr), Some(val_addr)) = (kv[0].as_str(), kv[1].as_str()) else { continue; };
+        if objects[key_addr]["type"] == "string" && objects[key_addr]["data"].as_str() == Some(key) {
+            if objects[val_addr]["type"] == "string" {
+                return objects[val_addr]["data"].as_str();
+            } else {
+                break;
+            }
+        }
+    }
+    None
+}

src/luau/json.rs

@@ -0,0 +1,327 @@
+use std::array;
+use std::collections::HashMap;
+use std::iter::Peekable;
+use std::ops::Index;
+use std::str::CharIndices;
+
+// A simple JSON parser and representation.
+// This parser supports only a subset of JSON specification and is intended for Luau's use cases.
+
+#[derive(Debug, PartialEq)]
+pub(crate) enum Json<'a> {
+    Null,
+    Bool(bool),
+    Integer(i64),
+    Number(f64),
+    String(&'a str),
+    Array(Vec<Json<'a>>),
+    Object(HashMap<&'a str, Json<'a>>),
+}
+
+impl<'a> Index<&str> for Json<'a> {
+    type Output = Json<'a>;
+
+    fn index(&self, key: &str) -> &Self::Output {
+        match self {
+            Json::Object(map) => map.get(key).unwrap_or(&Json::Null),
+            _ => &Json::Null,
+        }
+    }
+}
+
+impl PartialEq<&str> for Json<'_> {
+    fn eq(&self, other: &&str) -> bool {
+        matches!(self, Json::String(s) if s == other)
+    }
+}
+
+impl<'a> Json<'a> {
+    pub(crate) fn as_str(&self) -> Option<&'a str> {
+        match self {
+            Json::String(s) => Some(s),
+            _ => None,
+        }
+    }
+
+    pub(crate) fn as_i64(&self) -> Option<i64> {
+        match self {
+            Json::Integer(i) => Some(*i),
+            Json::Number(n) if n.fract() == 0.0 => Some(*n as i64),
+            _ => None,
+        }
+    }
+
+    pub(crate) fn as_u64(&self) -> Option<u64> {
+        self.as_i64()
+            .and_then(|i| if i >= 0 { Some(i as u64) } else { None })
+    }
+
+    pub(crate) fn as_array(&self) -> Option<&[Json<'a>]> {
+        match self {
+            Json::Array(arr) => Some(arr),
+            _ => None,
+        }
+    }
+
+    pub(crate) fn as_object(&self) -> Option<&HashMap<&'a str, Json<'a>>> {
+        match self {
+            Json::Object(map) => Some(map),
+            _ => None,
+        }
+    }
+}
+
+pub(crate) fn parse<'a>(s: &'a str) -> Result<Json<'a>, &'static str> {
+    let s = s.trim_ascii();
+    let mut chars = s.char_indices().peekable();
+    let value = parse_value(s, &mut chars)?;
+    Ok(value)
+}
+
+fn parse_value<'a>(s: &'a str, chars: &mut Peekable<CharIndices>) -> Result<Json<'a>, &'static str> {
+    skip_whitespace(chars);
+    match chars.peek() {
+        Some((_, '{')) => parse_object(s, chars),
+        Some((_, '[')) => parse_array(s, chars),
+        Some((_, '"')) => parse_string(s, chars).map(Json::String),
+        Some((_, 't' | 'f')) => parse_bool(chars),
+        Some((_, 'n')) => parse_null(chars),
+        Some((_, '-' | '0'..='9')) => parse_number(chars),
+        Some(_) => Err("unexpected character"),
+        None => Err("unexpected end of input"),
+    }
+}
+
+fn parse_object<'a>(s: &'a str, chars: &mut Peekable<CharIndices>) -> Result<Json<'a>, &'static str> {
+    chars.next(); // consume '{'
+
+    let mut map = HashMap::new();
+    skip_whitespace(chars);
+    if matches!(chars.peek(), Some((_, '}'))) {
+        chars.next();
+        return Ok(Json::Object(map));
+    }
+    loop {
+        skip_whitespace(chars);
+        let key = parse_string(s, chars)?;
+        skip_whitespace(chars);
+        if !matches!(chars.next(), Some((_, ':'))) {
+            return Err("expected ':'");
+        }
+        let value = parse_value(s, chars)?;
+        map.insert(key, value);
+        skip_whitespace(chars);
+        match chars.next() {
+            Some((_, ',')) => continue,
+            Some((_, '}')) => break,
+            _ => return Err("expected ',' or '}'"),
+        }
+    }
+    Ok(Json::Object(map))
+}
+
+fn parse_array<'a>(s: &'a str, chars: &mut Peekable<CharIndices>) -> Result<Json<'a>, &'static str> {
+    chars.next(); // consume '['
+
+    let mut arr = Vec::new();
+    skip_whitespace(chars);
+    if matches!(chars.peek(), Some((_, ']'))) {
+        chars.next();
+        return Ok(Json::Array(arr));
+    }
+    loop {
+        skip_whitespace(chars);
+        arr.push(parse_value(s, chars)?);
+        skip_whitespace(chars);
+        match chars.next() {
+            Some((_, ',')) => continue,
+            Some((_, ']')) => return Ok(Json::Array(arr)),
+            _ => return Err("expected ',' or ']'"),
+        }
+    }
+}
+
+fn parse_string<'a>(s: &'a str, chars: &mut Peekable<CharIndices>) -> Result<&'a str, &'static str> {
+    if !matches!(chars.next(), Some((_, '"'))) {
+        return Err("expected string starting with '\"'");
+    }
+    let start = chars.peek().map(|(i, _)| *i).unwrap_or(0);
+    for (i, c) in chars {
+        if c == '"' {
+            return Ok(&s[start..i]);
+        }
+    }
+    Err("unterminated string")
+}
+
+fn parse_number(chars: &mut Peekable<CharIndices>) -> Result<Json<'static>, &'static str> {
+    let mut is_float = false;
+    let mut num = String::new();
+    while let Some((_, c @ ('0'..='9' | '-' | '.' | 'e' | 'E' | '+'))) = chars.peek() {
+        num.push(*c);
+        is_float = is_float || matches!(c, '.' | 'e' | 'E');
+        chars.next();
+    }
+    if !is_float {
+        let i = num.parse::<i64>().map_err(|_| "invalid integer")?;
+        return Ok(Json::Integer(i));
+    }
+    let n = num.parse::<f64>().map_err(|_| "invalid number")?;
+    Ok(Json::Number(n))
+}
+
+fn parse_bool(chars: &mut Peekable<CharIndices>) -> Result<Json<'static>, &'static str> {
+    let bool = next_chars(chars);
+    if bool == [Some('t'), Some('r'), Some('u'), Some('e')] {
+        return Ok(Json::Bool(true));
+    }
+    if bool == [Some('f'), Some('a'), Some('l'), Some('s')] && matches!(chars.next(), Some((_, 'e'))) {
+        return Ok(Json::Bool(false));
+    }
+    Err("invalid boolean literal")
+}
+
+fn parse_null(chars: &mut Peekable<CharIndices>) -> Result<Json<'static>, &'static str> {
+    if next_chars(chars) == [Some('n'), Some('u'), Some('l'), Some('l')] {
+        return Ok(Json::Null);
+    }
+    Err("invalid \"null\" literal")
+}
+
+fn skip_whitespace(chars: &mut Peekable<CharIndices>) {
+    while let Some((_, ' ' | '\n' | '\r' | '\t')) = chars.peek() {
+        chars.next();
+    }
+}
+
+fn next_chars<const N: usize>(chars: &mut Peekable<CharIndices>) -> [Option<char>; N] {
+    array::from_fn(|_| chars.next().map(|(_, c)| c))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse() {
+        assert_eq!(parse("null").unwrap(), Json::Null);
+        assert_eq!(parse("true").unwrap(), Json::Bool(true));
+        assert_eq!(parse("false").unwrap(), Json::Bool(false));
+        assert_eq!(parse("42").unwrap(), Json::Integer(42));
+        assert_eq!(parse("42.0").unwrap(), Json::Number(42.0));
+        assert_eq!(parse(r#""hello""#).unwrap(), Json::String("hello"));
+        assert_eq!(
+            parse("[1,2.0,3]").unwrap(),
+            Json::Array(vec![Json::Integer(1), Json::Number(2.0), Json::Integer(3)])
+        );
+        let mut obj = HashMap::new();
+        obj.insert("key", Json::String("value"));
+        assert_eq!(parse(r#"{"key":"value"}"#).unwrap(), Json::Object(obj));
+    }
+
+    #[test]
+    fn test_whitespace_handling() {
+        assert_eq!(parse("  null  ").unwrap(), Json::Null);
+        assert_eq!(parse("  true  ").unwrap(), Json::Bool(true));
+        assert_eq!(
+            parse(" [ 1 , 2.0 , 3 ] ").unwrap(),
+            Json::Array(vec![Json::Integer(1), Json::Number(2.0), Json::Integer(3)])
+        );
+        let mut obj = HashMap::new();
+        obj.insert("key", Json::String("value"));
+        assert_eq!(parse(r#"  { "key" : "value" }  "#).unwrap(), Json::Object(obj));
+    }
+
+    #[test]
+    fn test_empty_collections() {
+        assert_eq!(parse("[]").unwrap(), Json::Array(vec![]));
+        assert_eq!(parse("{}").unwrap(), Json::Object(HashMap::new()));
+        assert_eq!(parse("[ ]").unwrap(), Json::Array(vec![]));
+        assert_eq!(parse("{ }").unwrap(), Json::Object(HashMap::new()));
+    }
+
+    #[test]
+    fn test_nested_structures() {
+        assert_eq!(
+            parse(r#"{"nested":{"inner":"value"}}"#).unwrap(),
+            Json::Object({
+                let mut outer = HashMap::new();
+                let mut inner = HashMap::new();
+                inner.insert("inner", Json::String("value"));
+                outer.insert("nested", Json::Object(inner));
+                outer
+            })
+        );
+        assert_eq!(
+            parse("[[1,2],[3,4]]").unwrap(),
+            Json::Array(vec![
+                Json::Array(vec![Json::Integer(1), Json::Integer(2)]),
+                Json::Array(vec![Json::Integer(3), Json::Integer(4)])
+            ])
+        );
+    }
+
+    #[test]
+    fn test_numbers() {
+        assert_eq!(parse("0").unwrap(), Json::Integer(0));
+        assert_eq!(parse("-42").unwrap(), Json::Integer(-42));
+        assert_eq!(parse("3.14").unwrap(), Json::Number(3.14));
+        assert_eq!(parse("-3.14").unwrap(), Json::Number(-3.14));
+        assert_eq!(parse("1e10").unwrap(), Json::Number(1e10));
+        assert_eq!(parse("1E10").unwrap(), Json::Number(1E10));
+        assert_eq!(parse("1e-10").unwrap(), Json::Number(1e-10));
+        assert_eq!(parse("1.5e+10").unwrap(), Json::Number(1.5e+10));
+    }
+
+    #[test]
+    fn test_strings() {
+        assert_eq!(parse(r#""""#).unwrap(), Json::String(""));
+        assert_eq!(parse(r#""hello world""#).unwrap(), Json::String("hello world"));
+        assert_eq!(
+            parse(r#""with spaces and 123""#).unwrap(),
+            Json::String("with spaces and 123")
+        );
+    }
+
+    #[test]
+    fn test_mixed_array() {
+        assert_eq!(
+            parse(r#"[null, true, false, 35.1, 42, "text", [], {}]"#).unwrap(),
+            Json::Array(vec![
+                Json::Null,
+                Json::Bool(true),
+                Json::Bool(false),
+                Json::Number(35.1),
+                Json::Integer(42),
+                Json::String("text"),
+                Json::Array(vec![]),
+                Json::Object(HashMap::new())
+            ])
+        );
+    }
+
+    #[test]
+    fn test_object_multiple_keys() {
+        let mut obj = HashMap::new();
+        obj.insert("a", Json::Integer(1));
+        obj.insert("b", Json::Bool(true));
+        obj.insert("c", Json::Null);
+        assert_eq!(parse(r#"{"a":1,"b":true,"c":null}"#).unwrap(), Json::Object(obj));
+    }
+
+    #[test]
+    fn test_error_cases() {
+        assert!(parse("").is_err());
+        assert!(parse("nul").is_err());
+        assert!(parse("tru").is_err()); // typos:ignore
+        assert!(parse("fals").is_err()); // typos:ignore
+        assert!(parse(r#""unterminated"#).is_err());
+        assert!(parse("[1,2,]").is_err());
+        assert!(parse(r#"{"key""#).is_err());
+        assert!(parse(r#"{"key":"value""#).is_err());
+        assert!(parse(r#"{"key":"value",}"#).is_err());
+        assert!(parse("invalid").is_err());
+        assert!(parse("[1 2]").is_err());
+        assert!(parse(r#"{"key":"value" "key2":"value2"}"#).is_err());
+    }
+}

src/luau/mod.rs

@@ -1,13 +1,15 @@
-use std::ffi::CStr;
+use std::ffi::{CStr, CString};
 use std::os::raw::c_int;
 use std::ptr;
 
 use crate::chunk::ChunkMode;
-use crate::error::Result;
+use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::state::{callback_error_ext, Lua};
+use crate::state::{callback_error_ext, ExtraData, Lua};
 use crate::traits::{FromLuaMulti, IntoLua};
+use crate::types::MaybeSend;
 
+pub use heap_dump::HeapDump;
 pub use require::{NavigateError, Require, TextRequirer};
 
 // Since Luau has some missing standard functions, we re-implement them here
@@ -17,10 +19,60 @@ impl Lua {
     /// and load modules.
     #[cfg(any(feature = "luau", doc))]
     #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
-    pub fn create_require_function<R: Require + 'static>(&self, require: R) -> Result<Function> {
+    pub fn create_require_function<R: Require + MaybeSend + 'static>(&self, require: R) -> Result<Function> {
         require::create_require_function(self, require)
     }
 
+    /// Set the memory category for subsequent allocations from this Lua state.
+    ///
+    /// The category "main" is reserved for the default memory category.
+    /// Maximum of 255 categories can be registered.
+    /// The category is set per Lua thread (state) and affects all allocations made from that
+    /// thread.
+    ///
+    /// Return error if too many categories are registered or if the category name is invalid.
+    ///
+    /// See [`Lua::heap_dump`] for tracking memory usage by category.
+    #[cfg(any(feature = "luau", doc))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub fn set_memory_category(&self, category: &str) -> Result<()> {
+        let lua = self.lock();
+
+        if category.contains(|c| !matches!(c, 'a'..='z' | 'A'..='Z' | '0'..='9' | '-' | '_')) {
+            return Err(Error::runtime("invalid memory category name"));
+        }
+        let cat_id = unsafe {
+            let extra = ExtraData::get(lua.state());
+            match ((*extra).mem_categories.iter().enumerate())
+                .find(|&(_, name)| name.as_bytes() == category.as_bytes())
+            {
+                Some((id, _)) => id as u8,
+                None => {
+                    let new_id = (*extra).mem_categories.len() as u8;
+                    if new_id == 255 {
+                        return Err(Error::runtime("too many memory categories registered"));
+                    }
+                    (*extra).mem_categories.push(CString::new(category).unwrap());
+                    new_id
+                }
+            }
+        };
+        unsafe { ffi::lua_setmemcat(lua.state(), cat_id as i32) };
+
+        Ok(())
+    }
+
+    /// Dumps the current Lua VM heap state.
+    ///
+    /// The returned `HeapDump` can be used to analyze memory usage.
+    /// It's recommended to call [`Lua::gc_collect`] before dumping the heap.
+    #[cfg(any(feature = "luau", doc))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub fn heap_dump(&self) -> Result<HeapDump> {
+        let lua = self.lock();
+        unsafe { heap_dump::HeapDump::new(lua.state()).ok_or_else(|| Error::runtime("unable to dump heap")) }
+    }
+
     pub(crate) unsafe fn configure_luau(&self) -> Result<()> {
         let globals = self.globals();
 
@@ -45,16 +97,17 @@ unsafe extern "C-unwind" fn lua_collectgarbage(state: *mut ffi::lua_State) -> c_
     let option = ffi::luaL_optstring(state, 1, cstr!("collect"));
     let option = CStr::from_ptr(option);
     let arg = ffi::luaL_optinteger(state, 2, 0);
+    let is_sandboxed = (*ExtraData::get(state)).sandboxed;
     match option.to_str() {
-        Ok("collect") => {
+        Ok("collect") if !is_sandboxed => {
             ffi::lua_gc(state, ffi::LUA_GCCOLLECT, 0);
             0
         }
-        Ok("stop") => {
+        Ok("stop") if !is_sandboxed => {
             ffi::lua_gc(state, ffi::LUA_GCSTOP, 0);
             0
         }
-        Ok("restart") => {
+        Ok("restart") if !is_sandboxed => {
             ffi::lua_gc(state, ffi::LUA_GCRESTART, 0);
             0
         }
@@ -64,12 +117,12 @@ unsafe extern "C-unwind" fn lua_collectgarbage(state: *mut ffi::lua_State) -> c_
             ffi::lua_pushnumber(state, kbytes + kbytes_rem / 1024.0);
             1
         }
-        Ok("step") => {
+        Ok("step") if !is_sandboxed => {
             let res = ffi::lua_gc(state, ffi::LUA_GCSTEP, arg as _);
             ffi::lua_pushboolean(state, res);
             1
         }
-        Ok("isrunning") => {
+        Ok("isrunning") if !is_sandboxed => {
             let res = ffi::lua_gc(state, ffi::LUA_GCISRUNNING, 0);
             ffi::lua_pushboolean(state, res);
             1
@@ -94,4 +147,6 @@ unsafe extern "C-unwind" fn lua_loadstring(state: *mut ffi::lua_State) -> c_int
     })
 }
 
+mod heap_dump;
+mod json;
 mod require;

src/luau/require.rs

@@ -1,12 +1,10 @@
 use std::cell::RefCell;
-use std::collections::VecDeque;
 use std::ffi::CStr;
 use std::io::Result as IoResult;
 use std::ops::{Deref, DerefMut};
 use std::os::raw::{c_char, c_int, c_void};
-use std::path::{Component, Path, PathBuf};
 use std::result::Result as StdResult;
-use std::{env, fmt, fs, mem, ptr};
+use std::{fmt, mem, ptr};
 
 use crate::error::{Error, Result};
 use crate::function::Function;
@@ -14,9 +12,10 @@ use crate::state::{callback_error_ext, Lua};
 use crate::table::Table;
 use crate::types::MaybeSend;
 
-/// An error that can occur during navigation in the Luau `require` system.
-#[cfg(any(feature = "luau", doc))]
-#[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+// TODO: Rename to FsRequirer
+pub use fs::TextRequirer;
+
+/// An error that can occur during navigation in the Luau `require-by-string` system.
 #[derive(Debug, Clone)]
 pub enum NavigateError {
     Ambiguous,
@@ -50,10 +49,11 @@ impl From<Error> for NavigateError {
 #[cfg(feature = "luau")]
 type WriteResult = ffi::luarequire_WriteResult;
 
-/// A trait for handling modules loading and navigation in the Luau `require` system.
-#[cfg(any(feature = "luau", doc))]
-#[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
-pub trait Require: MaybeSend {
+#[cfg(feature = "luau")]
+type ConfigStatus = ffi::luarequire_ConfigStatus;
+
+/// A trait for handling modules loading and navigation in the Luau `require-by-string` system.
+pub trait Require {
     /// Returns `true` if "require" is permitted for the given chunk name.
     fn is_require_allowed(&self, chunk_name: &str) -> bool;
 
@@ -73,7 +73,7 @@ pub trait Require: MaybeSend {
     /// Navigate to the given child directory.
     fn to_child(&mut self, name: &str) -> StdResult<(), NavigateError>;
 
-    /// Returns whether the context is currently pointing at a module
+    /// Returns whether the context is currently pointing at a module.
     fn has_module(&self) -> bool;
 
     /// Provides a cache key representing the current module.
@@ -103,203 +103,31 @@ impl fmt::Debug for dyn Require {
     }
 }
 
-/// The standard implementation of Luau `require` navigation.
-#[doc(hidden)]
-#[derive(Default, Debug)]
-pub struct TextRequirer {
-    abs_path: PathBuf,
-    rel_path: PathBuf,
-    module_path: PathBuf,
+struct Context {
+    require: Box<dyn Require>,
+    config_cache: Option<IoResult<Vec<u8>>>,
 }
 
-impl TextRequirer {
-    /// Creates a new `TextRequirer` instance.
-    pub fn new() -> Self {
-        Self::default()
-    }
-
-    fn normalize_chunk_name(chunk_name: &str) -> &str {
-        if let Some((path, line)) = chunk_name.split_once(':') {
-            if line.parse::<u32>().is_ok() {
-                return path;
-            }
-        }
-        chunk_name
-    }
-
-    // Normalizes the path by removing unnecessary components
-    fn normalize_path(path: &Path) -> PathBuf {
-        let mut components = VecDeque::new();
-
-        for comp in path.components() {
-            match comp {
-                Component::Prefix(..) | Component::RootDir => {
-                    components.push_back(comp);
-                }
-                Component::CurDir => {}
-                Component::ParentDir => {
-                    if matches!(components.back(), None | Some(Component::ParentDir)) {
-                        components.push_back(Component::ParentDir);
-                    } else if matches!(components.back(), Some(Component::Normal(..))) {
-                        components.pop_back();
-                    }
-                }
-                Component::Normal(..) => components.push_back(comp),
-            }
-        }
-
-        if matches!(components.front(), None | Some(Component::Normal(..))) {
-            components.push_front(Component::CurDir);
-        }
-
-        // Join the components back together
-        components.into_iter().collect()
-    }
-
-    fn find_module(path: &Path) -> StdResult<PathBuf, NavigateError> {
-        let mut found_path = None;
-
-        if path.components().next_back() != Some(Component::Normal("init".as_ref())) {
-            let current_ext = (path.extension().and_then(|s| s.to_str()))
-                .map(|s| format!("{s}."))
-                .unwrap_or_default();
-            for ext in ["luau", "lua"] {
-                let candidate = path.with_extension(format!("{current_ext}{ext}"));
-                if candidate.is_file() && found_path.replace(candidate).is_some() {
-                    return Err(NavigateError::Ambiguous);
-                }
-            }
-        }
-        if path.is_dir() {
-            for component in ["init.luau", "init.lua"] {
-                let candidate = path.join(component);
-                if candidate.is_file() && found_path.replace(candidate).is_some() {
-                    return Err(NavigateError::Ambiguous);
-                }
-            }
-
-            if found_path.is_none() {
-                found_path = Some(PathBuf::new());
-            }
-        }
-
-        found_path.ok_or(NavigateError::NotFound)
-    }
-}
-
-impl Require for TextRequirer {
-    fn is_require_allowed(&self, chunk_name: &str) -> bool {
-        chunk_name.starts_with('@')
-    }
-
-    fn reset(&mut self, chunk_name: &str) -> StdResult<(), NavigateError> {
-        if !chunk_name.starts_with('@') {
-            return Err(NavigateError::NotFound);
-        }
-        let chunk_name = Self::normalize_chunk_name(&chunk_name[1..]);
-        let chunk_path = Self::normalize_path(chunk_name.as_ref());
-
-        if chunk_path.extension() == Some("rs".as_ref()) {
-            let cwd = env::current_dir().map_err(|_| NavigateError::NotFound)?;
-            self.abs_path = Self::normalize_path(&cwd.join(&chunk_path));
-            self.rel_path = chunk_path;
-            self.module_path = PathBuf::new();
-
-            return Ok(());
-        }
-
-        if chunk_path.is_absolute() {
-            let module_path = Self::find_module(&chunk_path)?;
-            self.abs_path = chunk_path.clone();
-            self.rel_path = chunk_path;
-            self.module_path = module_path;
-        } else {
-            // Relative path
-            let cwd = env::current_dir().map_err(|_| NavigateError::NotFound)?;
-            let abs_path = Self::normalize_path(&cwd.join(&chunk_path));
-            let module_path = Self::find_module(&abs_path)?;
-            self.abs_path = abs_path;
-            self.rel_path = chunk_path;
-            self.module_path = module_path;
-        }
-
-        Ok(())
-    }
-
-    fn jump_to_alias(&mut self, path: &str) -> StdResult<(), NavigateError> {
-        let path = Self::normalize_path(path.as_ref());
-        let module_path = Self::find_module(&path)?;
-
-        self.abs_path = path.clone();
-        self.rel_path = path;
-        self.module_path = module_path;
-
-        Ok(())
-    }
-
-    fn to_parent(&mut self) -> StdResult<(), NavigateError> {
-        let mut abs_path = self.abs_path.clone();
-        if !abs_path.pop() {
-            return Err(NavigateError::NotFound);
-        }
-        let mut rel_parent = self.rel_path.clone();
-        rel_parent.pop();
-        let module_path = Self::find_module(&abs_path)?;
-
-        self.abs_path = abs_path;
-        self.rel_path = Self::normalize_path(&rel_parent);
-        self.module_path = module_path;
-
-        Ok(())
-    }
-
-    fn to_child(&mut self, name: &str) -> StdResult<(), NavigateError> {
-        let abs_path = self.abs_path.join(name);
-        let rel_path = self.rel_path.join(name);
-        let module_path = Self::find_module(&abs_path)?;
-
-        self.abs_path = abs_path;
-        self.rel_path = rel_path;
-        self.module_path = module_path;
-
-        Ok(())
-    }
-
-    fn has_module(&self) -> bool {
-        self.module_path.is_file()
-    }
-
-    fn cache_key(&self) -> String {
-        self.module_path.display().to_string()
-    }
-
-    fn has_config(&self) -> bool {
-        self.abs_path.is_dir() && self.abs_path.join(".luaurc").is_file()
-    }
-
-    fn config(&self) -> IoResult<Vec<u8>> {
-        fs::read(self.abs_path.join(".luaurc"))
-    }
-
-    fn loader(&self, lua: &Lua) -> Result<Function> {
-        let name = format!("@{}", self.rel_path.display());
-        lua.load(&*self.module_path).set_name(name).into_function()
-    }
-}
-
-struct Context(Box<dyn Require>);
-
 impl Deref for Context {
     type Target = dyn Require;
 
     fn deref(&self) -> &Self::Target {
-        &*self.0
+        &*self.require
     }
 }
 
 impl DerefMut for Context {
     fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut *self.0
+        &mut *self.require
+    }
+}
+
+impl Context {
+    fn new(require: impl Require + MaybeSend + 'static) -> Self {
+        Context {
+            require: Box::new(require),
+            config_cache: None,
+        }
     }
 }
 
@@ -424,9 +252,18 @@ pub(super) unsafe extern "C-unwind" fn init_config(config: *mut ffi::luarequire_
         write_to_buffer(buffer, buffer_size, size_out, cache_key.as_bytes())
     }
 
-    unsafe extern "C-unwind" fn is_config_present(state: *mut ffi::lua_State, ctx: *mut c_void) -> bool {
-        let this = try_borrow!(state, ctx);
-        this.has_config()
+    unsafe extern "C-unwind" fn get_config_status(
+        state: *mut ffi::lua_State,
+        ctx: *mut c_void,
+    ) -> ConfigStatus {
+        let mut this = try_borrow_mut!(state, ctx);
+        if this.has_config() {
+            this.config_cache = Some(this.config());
+            if let Some(Ok(data)) = &this.config_cache {
+                return detect_config_format(data);
+            }
+        }
+        ConfigStatus::Absent
     }
 
     unsafe extern "C-unwind" fn get_config(
@@ -436,8 +273,10 @@ pub(super) unsafe extern "C-unwind" fn init_config(config: *mut ffi::luarequire_
         buffer_size: usize,
         size_out: *mut usize,
     ) -> WriteResult {
-        let this = try_borrow!(state, ctx);
-        let config = callback_error_ext(state, ptr::null_mut(), true, move |_, _| Ok(this.config()?));
+        let mut this = try_borrow_mut!(state, ctx);
+        let config = callback_error_ext(state, ptr::null_mut(), true, move |_, _| {
+            Ok(this.config_cache.take().unwrap_or_else(|| this.config())?)
+        });
         write_to_buffer(buffer, buffer_size, size_out, &config)
     }
 
@@ -460,18 +299,33 @@ pub(super) unsafe extern "C-unwind" fn init_config(config: *mut ffi::luarequire_
     (*config).is_require_allowed = is_require_allowed;
     (*config).reset = reset;
     (*config).jump_to_alias = jump_to_alias;
+    (*config).to_alias_override = None;
+    (*config).to_alias_fallback = None;
     (*config).to_parent = to_parent;
     (*config).to_child = to_child;
     (*config).is_module_present = is_module_present;
     (*config).get_chunkname = get_chunkname;
     (*config).get_loadname = get_loadname;
     (*config).get_cache_key = get_cache_key;
-    (*config).is_config_present = is_config_present;
+    (*config).get_config_status = get_config_status;
     (*config).get_alias = None;
     (*config).get_config = Some(get_config);
     (*config).load = load;
 }
 
+/// Detect configuration file format (JSON or Luau)
+#[cfg(feature = "luau")]
+fn detect_config_format(data: &[u8]) -> ConfigStatus {
+    let data = data.trim_ascii();
+    if data.starts_with(b"{") {
+        let data = &data[1..].trim_ascii_start();
+        if data.starts_with(b"\"") || data == b"}" {
+            return ConfigStatus::PresentJson;
+        }
+    }
+    ConfigStatus::PresentLuau
+}
+
 /// Helper function to write data to a buffer
 #[cfg(feature = "luau")]
 unsafe fn write_to_buffer(
@@ -494,7 +348,10 @@ unsafe fn write_to_buffer(
 }
 
 #[cfg(feature = "luau")]
-pub fn create_require_function<R: Require + 'static>(lua: &Lua, require: R) -> Result<Function> {
+pub(super) fn create_require_function<R: Require + MaybeSend + 'static>(
+    lua: &Lua,
+    require: R,
+) -> Result<Function> {
     unsafe extern "C-unwind" fn find_current_file(state: *mut ffi::lua_State) -> c_int {
         let mut ar: ffi::lua_Debug = mem::zeroed();
         for level in 2.. {
@@ -519,7 +376,7 @@ pub fn create_require_function<R: Require + 'static>(lua: &Lua, require: R) -> R
 
     let (get_cache_key, find_current_file, proxyrequire, registered_modules, loader_cache) = unsafe {
         lua.exec_raw::<(Function, Function, Function, Table, Table)>((), move |state| {
-            let context = Context(Box::new(require));
+            let context = Context::new(require);
             let context_ptr = ffi::lua_newuserdata_t(state, RefCell::new(context));
             ffi::lua_pushcclosured(state, get_cache_key, cstr!("get_cache_key"), 1);
             ffi::lua_pushcfunctiond(state, find_current_file, cstr!("find_current_file"));
@@ -541,10 +398,26 @@ pub fn create_require_function<R: Require + 'static>(lua: &Lua, require: R) -> R
         1
     }
 
-    let (error, r#type) = unsafe {
-        lua.exec_raw::<(Function, Function)>((), move |state| {
+    unsafe extern "C-unwind" fn to_lowercase(state: *mut ffi::lua_State) -> c_int {
+        let s = ffi::luaL_checkstring(state, 1);
+        let s = CStr::from_ptr(s);
+        if !s.to_bytes().iter().any(|&c| c.is_ascii_uppercase()) {
+            // If the string does not contain any uppercase ASCII letters, return it as is
+            return 1;
+        }
+        callback_error_ext(state, ptr::null_mut(), true, |extra, _| {
+            let s = (s.to_bytes().iter())
+                .map(|&c| c.to_ascii_lowercase())
+                .collect::<bstr::BString>();
+            (*extra).raw_lua().push(s).map(|_| 1)
+        })
+    }
+
+    let (error, r#type, to_lowercase) = unsafe {
+        lua.exec_raw::<(Function, Function, Function)>((), move |state| {
             ffi::lua_pushcfunctiond(state, error, cstr!("error"));
             ffi::lua_pushcfunctiond(state, r#type, cstr!("type"));
+            ffi::lua_pushcfunctiond(state, to_lowercase, cstr!("to_lowercase"));
         })
     }?;
 
@@ -557,6 +430,7 @@ pub fn create_require_function<R: Require + 'static>(lua: &Lua, require: R) -> R
     env.raw_set("LOADER_CACHE", loader_cache)?;
     env.raw_set("error", error)?;
     env.raw_set("type", r#type)?;
+    env.raw_set("to_lowercase", to_lowercase)?;
 
     lua.load(
         r#"
@@ -566,7 +440,7 @@ pub fn create_require_function<R: Require + 'static>(lua: &Lua, require: R) -> R
         end
 
         -- Check if the module (path) is explicitly registered
-        local maybe_result = REGISTERED_MODULES[path]
+        local maybe_result = REGISTERED_MODULES[to_lowercase(path)]
         if maybe_result ~= nil then
             return maybe_result
         end
@@ -594,52 +468,4 @@ pub fn create_require_function<R: Require + 'static>(lua: &Lua, require: R) -> R
     .into_function()
 }
 
-#[cfg(test)]
-mod tests {
-    use std::path::Path;
-
-    use super::TextRequirer;
-
-    #[test]
-    fn test_path_normalize() {
-        for (input, expected) in [
-            // Basic formatting checks
-            ("", "./"),
-            (".", "./"),
-            ("a/relative/path", "./a/relative/path"),
-            // Paths containing extraneous '.' and '/' symbols
-            ("./remove/extraneous/symbols/", "./remove/extraneous/symbols"),
-            ("./remove/extraneous//symbols", "./remove/extraneous/symbols"),
-            ("./remove/extraneous/symbols/.", "./remove/extraneous/symbols"),
-            ("./remove/extraneous/./symbols", "./remove/extraneous/symbols"),
-            ("../remove/extraneous/symbols/", "../remove/extraneous/symbols"),
-            ("../remove/extraneous//symbols", "../remove/extraneous/symbols"),
-            ("../remove/extraneous/symbols/.", "../remove/extraneous/symbols"),
-            ("../remove/extraneous/./symbols", "../remove/extraneous/symbols"),
-            ("/remove/extraneous/symbols/", "/remove/extraneous/symbols"),
-            ("/remove/extraneous//symbols", "/remove/extraneous/symbols"),
-            ("/remove/extraneous/symbols/.", "/remove/extraneous/symbols"),
-            ("/remove/extraneous/./symbols", "/remove/extraneous/symbols"),
-            // Paths containing '..'
-            ("./remove/me/..", "./remove"),
-            ("./remove/me/../", "./remove"),
-            ("../remove/me/..", "../remove"),
-            ("../remove/me/../", "../remove"),
-            ("/remove/me/..", "/remove"),
-            ("/remove/me/../", "/remove"),
-            ("./..", "../"),
-            ("./../", "../"),
-            ("../..", "../../"),
-            ("../../", "../../"),
-            // '..' disappears if path is absolute and component is non-erasable
-            ("/../", "/"),
-        ] {
-            let path = TextRequirer::normalize_path(input.as_ref());
-            assert_eq!(
-                &path,
-                expected.as_ref() as &Path,
-                "wrong normalization for {input}"
-            );
-        }
-    }
-}
+mod fs;

src/luau/require/fs.rs

@@ -0,0 +1,278 @@
+use std::collections::VecDeque;
+use std::io::Result as IoResult;
+use std::path::{Component, Path, PathBuf};
+use std::result::Result as StdResult;
+use std::{env, fs};
+
+use crate::error::Result;
+use crate::function::Function;
+use crate::state::Lua;
+
+use super::{NavigateError, Require};
+
+/// The standard implementation of Luau `require-by-string` navigation.
+#[derive(Default, Debug)]
+pub struct TextRequirer {
+    /// An absolute path to the current Luau module (not mapped to a physical file)
+    abs_path: PathBuf,
+    /// A relative path to the current Luau module (not mapped to a physical file)
+    rel_path: PathBuf,
+    /// A physical path to the current Luau module, which is a file or a directory with an
+    /// `init.lua(u)` file
+    resolved_path: Option<PathBuf>,
+}
+
+impl TextRequirer {
+    /// The prefix used for chunk names in the require system.
+    /// Only chunk names starting with this prefix are allowed to be used in `require`.
+    const CHUNK_PREFIX: &str = "@";
+
+    /// The file extensions that are considered valid for Luau modules.
+    const FILE_EXTENSIONS: &[&str] = &["luau", "lua"];
+
+    /// The filename for the JSON configuration file.
+    const LUAURC_CONFIG_FILENAME: &str = ".luaurc";
+
+    /// The filename for the Luau configuration file.
+    const LUAU_CONFIG_FILENAME: &str = ".config.luau";
+
+    /// Creates a new `TextRequirer` instance.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    fn normalize_chunk_name(chunk_name: &str) -> &str {
+        if let Some((path, line)) = chunk_name.rsplit_once(':') {
+            if line.parse::<u32>().is_ok() {
+                return path;
+            }
+        }
+        chunk_name
+    }
+
+    // Normalizes the path by removing unnecessary components
+    fn normalize_path(path: &Path) -> PathBuf {
+        let mut components = VecDeque::new();
+
+        for comp in path.components() {
+            match comp {
+                Component::Prefix(..) | Component::RootDir => {
+                    components.push_back(comp);
+                }
+                Component::CurDir => {}
+                Component::ParentDir => {
+                    if matches!(components.back(), None | Some(Component::ParentDir)) {
+                        components.push_back(Component::ParentDir);
+                    } else if matches!(components.back(), Some(Component::Normal(..))) {
+                        components.pop_back();
+                    }
+                }
+                Component::Normal(..) => components.push_back(comp),
+            }
+        }
+
+        if matches!(components.front(), None | Some(Component::Normal(..))) {
+            components.push_front(Component::CurDir);
+        }
+
+        // Join the components back together
+        components.into_iter().collect()
+    }
+
+    /// Resolve a Luau module path to a physical file or directory.
+    ///
+    /// Empty directories without init files are considered valid as "intermediate" directories.
+    fn resolve_module(path: &Path) -> StdResult<Option<PathBuf>, NavigateError> {
+        let mut found_path = None;
+
+        if path.components().next_back() != Some(Component::Normal("init".as_ref())) {
+            let current_ext = (path.extension().and_then(|s| s.to_str()))
+                .map(|s| format!("{s}."))
+                .unwrap_or_default();
+            for ext in Self::FILE_EXTENSIONS {
+                let candidate = path.with_extension(format!("{current_ext}{ext}"));
+                if candidate.is_file() && found_path.replace(candidate).is_some() {
+                    return Err(NavigateError::Ambiguous);
+                }
+            }
+        }
+        if path.is_dir() {
+            for component in Self::FILE_EXTENSIONS.iter().map(|ext| format!("init.{ext}")) {
+                let candidate = path.join(component);
+                if candidate.is_file() && found_path.replace(candidate).is_some() {
+                    return Err(NavigateError::Ambiguous);
+                }
+            }
+
+            if found_path.is_none() {
+                // Directories without init files are considered valid "intermediate" path
+                return Ok(None);
+            }
+        }
+
+        Ok(Some(found_path.ok_or(NavigateError::NotFound)?))
+    }
+}
+
+impl Require for TextRequirer {
+    fn is_require_allowed(&self, chunk_name: &str) -> bool {
+        chunk_name.starts_with(Self::CHUNK_PREFIX)
+    }
+
+    fn reset(&mut self, chunk_name: &str) -> StdResult<(), NavigateError> {
+        if !chunk_name.starts_with(Self::CHUNK_PREFIX) {
+            return Err(NavigateError::NotFound);
+        }
+        let chunk_name = Self::normalize_chunk_name(&chunk_name[1..]);
+        let chunk_path = Self::normalize_path(chunk_name.as_ref());
+
+        if chunk_path.extension() == Some("rs".as_ref()) {
+            // Special case for Rust source files, reset to the current directory
+            let chunk_filename = chunk_path.file_name().unwrap();
+            let cwd = env::current_dir().map_err(|_| NavigateError::NotFound)?;
+            self.abs_path = Self::normalize_path(&cwd.join(chunk_filename));
+            self.rel_path = ([Component::CurDir, Component::Normal(chunk_filename)].into_iter()).collect();
+            self.resolved_path = None;
+
+            return Ok(());
+        }
+
+        if chunk_path.is_absolute() {
+            let resolved_path = Self::resolve_module(&chunk_path)?;
+            self.abs_path = chunk_path.clone();
+            self.rel_path = chunk_path;
+            self.resolved_path = resolved_path;
+        } else {
+            // Relative path
+            let cwd = env::current_dir().map_err(|_| NavigateError::NotFound)?;
+            let abs_path = Self::normalize_path(&cwd.join(&chunk_path));
+            let resolved_path = Self::resolve_module(&abs_path)?;
+            self.abs_path = abs_path;
+            self.rel_path = chunk_path;
+            self.resolved_path = resolved_path;
+        }
+
+        Ok(())
+    }
+
+    fn jump_to_alias(&mut self, path: &str) -> StdResult<(), NavigateError> {
+        let path = Self::normalize_path(path.as_ref());
+        let resolved_path = Self::resolve_module(&path)?;
+
+        self.abs_path = path.clone();
+        self.rel_path = path;
+        self.resolved_path = resolved_path;
+
+        Ok(())
+    }
+
+    fn to_parent(&mut self) -> StdResult<(), NavigateError> {
+        let mut abs_path = self.abs_path.clone();
+        if !abs_path.pop() {
+            // It's important to return `NotFound` if we reached the root, as it's a "recoverable" error if we
+            // cannot go beyond the root directory.
+            // Luau "require-by-string` has a special logic to search for config file to resolve aliases.
+            return Err(NavigateError::NotFound);
+        }
+        let mut rel_parent = self.rel_path.clone();
+        rel_parent.pop();
+        let resolved_path = Self::resolve_module(&abs_path)?;
+
+        self.abs_path = abs_path;
+        self.rel_path = Self::normalize_path(&rel_parent);
+        self.resolved_path = resolved_path;
+
+        Ok(())
+    }
+
+    fn to_child(&mut self, name: &str) -> StdResult<(), NavigateError> {
+        let abs_path = self.abs_path.join(name);
+        let rel_path = self.rel_path.join(name);
+        let resolved_path = Self::resolve_module(&abs_path)?;
+
+        self.abs_path = abs_path;
+        self.rel_path = rel_path;
+        self.resolved_path = resolved_path;
+
+        Ok(())
+    }
+
+    fn has_module(&self) -> bool {
+        (self.resolved_path.as_deref())
+            .map(Path::is_file)
+            .unwrap_or(false)
+    }
+
+    fn cache_key(&self) -> String {
+        self.resolved_path.as_deref().unwrap().display().to_string()
+    }
+
+    fn has_config(&self) -> bool {
+        self.abs_path.is_dir() && self.abs_path.join(Self::LUAURC_CONFIG_FILENAME).is_file()
+            || self.abs_path.is_dir() && self.abs_path.join(Self::LUAU_CONFIG_FILENAME).is_file()
+    }
+
+    fn config(&self) -> IoResult<Vec<u8>> {
+        if self.abs_path.join(Self::LUAURC_CONFIG_FILENAME).is_file() {
+            return fs::read(self.abs_path.join(Self::LUAURC_CONFIG_FILENAME));
+        }
+        fs::read(self.abs_path.join(Self::LUAU_CONFIG_FILENAME))
+    }
+
+    fn loader(&self, lua: &Lua) -> Result<Function> {
+        let name = format!("@{}", self.rel_path.display());
+        lua.load(self.resolved_path.as_deref().unwrap())
+            .set_name(name)
+            .into_function()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::path::Path;
+
+    use super::TextRequirer;
+
+    #[test]
+    fn test_path_normalize() {
+        for (input, expected) in [
+            // Basic formatting checks
+            ("", "./"),
+            (".", "./"),
+            ("a/relative/path", "./a/relative/path"),
+            // Paths containing extraneous '.' and '/' symbols
+            ("./remove/extraneous/symbols/", "./remove/extraneous/symbols"),
+            ("./remove/extraneous//symbols", "./remove/extraneous/symbols"),
+            ("./remove/extraneous/symbols/.", "./remove/extraneous/symbols"),
+            ("./remove/extraneous/./symbols", "./remove/extraneous/symbols"),
+            ("../remove/extraneous/symbols/", "../remove/extraneous/symbols"),
+            ("../remove/extraneous//symbols", "../remove/extraneous/symbols"),
+            ("../remove/extraneous/symbols/.", "../remove/extraneous/symbols"),
+            ("../remove/extraneous/./symbols", "../remove/extraneous/symbols"),
+            ("/remove/extraneous/symbols/", "/remove/extraneous/symbols"),
+            ("/remove/extraneous//symbols", "/remove/extraneous/symbols"),
+            ("/remove/extraneous/symbols/.", "/remove/extraneous/symbols"),
+            ("/remove/extraneous/./symbols", "/remove/extraneous/symbols"),
+            // Paths containing '..'
+            ("./remove/me/..", "./remove"),
+            ("./remove/me/../", "./remove"),
+            ("../remove/me/..", "../remove"),
+            ("../remove/me/../", "../remove"),
+            ("/remove/me/..", "/remove"),
+            ("/remove/me/../", "/remove"),
+            ("./..", "../"),
+            ("./../", "../"),
+            ("../..", "../../"),
+            ("../../", "../../"),
+            // '..' disappears if path is absolute and component is non-erasable
+            ("/../", "/"),
+        ] {
+            let path = TextRequirer::normalize_path(input.as_ref());
+            assert_eq!(
+                &path,
+                expected.as_ref() as &Path,
+                "wrong normalization for {input}"
+            );
+        }
+    }
+}

src/memory.rs

@@ -83,7 +83,7 @@ impl MemoryState {
     }
 
     // Does nothing apart from calling `f()`, we don't need to bypass any limits
-    #[cfg(any(feature = "lua52", feature = "lua53", feature = "lua54"))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
     #[inline]
     pub(crate) unsafe fn relax_limit_with(_state: *mut ffi::lua_State, f: impl FnOnce()) {
         f();

src/multi.rs

@@ -204,6 +204,23 @@ impl IntoLuaMulti for MultiValue {
     }
 }
 
+impl IntoLuaMulti for &MultiValue {
+    #[inline]
+    fn into_lua_multi(self, _: &Lua) -> Result<MultiValue> {
+        Ok(self.clone())
+    }
+
+    #[inline]
+    unsafe fn push_into_stack_multi(self, lua: &RawLua) -> Result<c_int> {
+        let nresults = self.len() as i32;
+        check_stack(lua.state(), nresults + 1)?;
+        for value in &self.0 {
+            lua.push_value(value)?;
+        }
+        Ok(nresults)
+    }
+}
+
 impl FromLuaMulti for MultiValue {
     #[inline]
     fn from_lua_multi(values: MultiValue, _: &Lua) -> Result<Self> {
@@ -297,6 +314,15 @@ impl<T: IntoLua> IntoLuaMulti for Variadic<T> {
     fn into_lua_multi(self, lua: &Lua) -> Result<MultiValue> {
         MultiValue::from_lua_iter(lua, self)
     }
+
+    unsafe fn push_into_stack_multi(self, lua: &RawLua) -> Result<c_int> {
+        let nresults = self.len() as i32;
+        check_stack(lua.state(), nresults + 1)?;
+        for value in self.0 {
+            value.push_into_stack(lua)?;
+        }
+        Ok(nresults)
+    }
 }
 
 impl<T: FromLua> FromLuaMulti for Variadic<T> {

src/prelude.rs

@@ -25,7 +25,8 @@ pub use crate::HookTriggers as LuaHookTriggers;
 #[doc(no_inline)]
 pub use crate::{
     CompileConstant as LuaCompileConstant, CoverageInfo as LuaCoverageInfo,
-    NavigateError as LuaNavigateError, Require as LuaRequire, Vector as LuaVector,
+    NavigateError as LuaNavigateError, Require as LuaRequire, TextRequirer as LuaTextRequirer,
+    Vector as LuaVector,
 };
 
 #[cfg(feature = "async")]
@@ -35,5 +36,6 @@ pub use crate::{AsyncThread as LuaAsyncThread, LuaNativeAsyncFn};
 #[cfg(feature = "serde")]
 #[doc(no_inline)]
 pub use crate::{
-    DeserializeOptions as LuaDeserializeOptions, LuaSerdeExt, SerializeOptions as LuaSerializeOptions,
+    DeserializeOptions as LuaDeserializeOptions, LuaSerdeExt, SerializableValue as LuaSerializableValue,
+    SerializeOptions as LuaSerializeOptions,
 };

src/serde/de.rs

@@ -15,11 +15,12 @@ use crate::userdata::AnyUserData;
 use crate::value::Value;
 
 /// A struct for deserializing Lua values into Rust values.
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Deserializer {
     value: Value,
     options: Options,
     visited: Rc<RefCell<FxHashSet<*const c_void>>>,
+    len: Option<usize>, // A length hint for sequences
 }
 
 /// A struct with options to change default deserializer behavior.
@@ -54,6 +55,19 @@ pub struct Options {
     ///
     /// Default: **false**
     pub encode_empty_tables_as_array: bool,
+
+    /// If true, enable detection of mixed tables.
+    ///
+    /// A mixed table is a table that has both array-like and map-like entries or several borders.
+    /// See [`The Length Operator`] documentation for details about borders.
+    ///
+    /// When this option is disabled, a table with a non-zero length (with one or more borders) will
+    /// be always encoded as an array.
+    ///
+    /// Default: **false**
+    ///
+    /// [`The Length Operator`]: https://www.lua.org/manual/5.4/manual.html#3.4.7
+    pub detect_mixed_tables: bool,
 }
 
 impl Default for Options {
@@ -70,6 +84,7 @@ impl Options {
             deny_recursive_tables: true,
             sort_keys: false,
             encode_empty_tables_as_array: false,
+            detect_mixed_tables: false,
         }
     }
 
@@ -108,6 +123,15 @@ impl Options {
         self.encode_empty_tables_as_array = enabled;
         self
     }
+
+    /// Sets [`detect_mixed_tables`] option.
+    ///
+    /// [`detect_mixed_tables`]: #structfield.detect_mixed_tables
+    #[must_use]
+    pub const fn detect_mixed_tables(mut self, enable: bool) -> Self {
+        self.detect_mixed_tables = enable;
+        self
+    }
 }
 
 impl Deserializer {
@@ -121,7 +145,7 @@ impl Deserializer {
         Deserializer {
             value,
             options,
-            visited: Rc::new(RefCell::new(FxHashSet::default())),
+            ..Default::default()
         }
     }
 
@@ -130,8 +154,14 @@ impl Deserializer {
             value,
             options,
             visited,
+            ..Default::default()
         }
     }
+
+    fn with_len(mut self, len: usize) -> Self {
+        self.len = Some(len);
+        self
+    }
 }
 
 impl<'de> serde::Deserializer<'de> for Deserializer {
@@ -155,17 +185,22 @@ impl<'de> serde::Deserializer<'de> for Deserializer {
                 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(ref t) if self.options.encode_empty_tables_as_array && t.is_empty() => {
-                self.deserialize_seq(visitor)
+            Value::Table(ref t) => {
+                if let Some(len) = t.encode_as_array(self.options) {
+                    self.with_len(len).deserialize_seq(visitor)
+                } else {
+                    self.deserialize_map(visitor)
+                }
             }
-            Value::Table(_) => self.deserialize_map(visitor),
             Value::LightUserData(ud) if ud.0.is_null() => visitor.visit_none(),
             Value::UserData(ud) if ud.is_serializable() => {
                 serde_userdata(ud, |value| value.deserialize_any(visitor))
             }
             #[cfg(feature = "luau")]
-            Value::Buffer(buf) => visitor.visit_bytes(unsafe { buf.as_slice() }),
+            Value::Buffer(buf) => {
+                let lua = buf.0.lua.lock();
+                visitor.visit_bytes(buf.as_slice(&lua))
+            }
             Value::Function(_)
             | Value::Thread(_)
             | Value::UserData(_)
@@ -267,14 +302,14 @@ impl<'de> serde::Deserializer<'de> for Deserializer {
             Value::Table(t) => {
                 let _guard = RecursionGuard::new(&t, &self.visited);
 
-                let len = t.raw_len();
+                let len = self.len.unwrap_or_else(|| t.raw_len());
                 let mut deserializer = SeqDeserializer {
-                    seq: t.sequence_values(),
+                    seq: t.sequence_values().with_len(len),
                     options: self.options,
                     visited: self.visited,
                 };
                 let seq = visitor.visit_seq(&mut deserializer)?;
-                if deserializer.seq.count() == 0 {
+                if deserializer.seq.next().is_none() {
                     Ok(seq)
                 } else {
                     Err(de::Error::invalid_length(len, &"fewer elements in the table"))

src/serde/ser.rs

@@ -256,7 +256,7 @@ impl<'a> ser::Serializer for Serializer<'a> {
     fn serialize_seq(self, len: Option<usize>) -> Result<Self::SerializeSeq> {
         let table = self.lua.create_table_with_capacity(len.unwrap_or(0), 0)?;
         if self.options.set_array_metatable {
-            table.set_metatable(Some(self.lua.array_metatable()));
+            table.set_metatable(Some(self.lua.array_metatable()))?;
         }
         Ok(SerializeSeq::new(self.lua, table, self.options))
     }
@@ -529,8 +529,8 @@ impl ser::SerializeStruct for SerializeStruct<'_> {
     fn end(self) -> Result<Value> {
         match self.inner {
             Some(table @ Value::Table(_)) => Ok(table),
-            Some(value) if self.options.detect_serde_json_arbitrary_precision => {
-                let number_s = value.as_str().expect("not an arbitrary precision number");
+            Some(value @ Value::String(_)) if self.options.detect_serde_json_arbitrary_precision => {
+                let number_s = value.to_string()?;
                 if number_s.contains(['.', 'e', 'E']) {
                     if let Ok(number) = number_s.parse().map(Value::Number) {
                         return Ok(number);

src/state.rs

@@ -8,9 +8,9 @@ use std::result::Result as StdResult;
 use std::{fmt, mem, ptr};
 
 use crate::chunk::{AsChunk, Chunk};
+use crate::debug::Debug;
 use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::hook::Debug;
 use crate::memory::MemoryState;
 use crate::multi::MultiValue;
 use crate::scope::Scope;
@@ -28,7 +28,7 @@ use crate::util::{assert_stack, check_stack, protect_lua_closure, push_string, r
 use crate::value::{Nil, Value};
 
 #[cfg(not(feature = "luau"))]
-use crate::{hook::HookTriggers, types::HookKind};
+use crate::{debug::HookTriggers, types::HookKind};
 
 #[cfg(any(feature = "luau", doc))]
 use crate::{buffer::Buffer, chunk::Compiler};
@@ -37,6 +37,7 @@ use crate::{buffer::Buffer, chunk::Compiler};
 use {
     crate::types::LightUserData,
     std::future::{self, Future},
+    std::task::Poll,
 };
 
 #[cfg(feature = "serde")]
@@ -72,8 +73,8 @@ pub(crate) struct LuaGuard(ArcReentrantMutexGuard<RawLua>);
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum GCMode {
     Incremental,
-    #[cfg(feature = "lua54")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
     Generational,
 }
 
@@ -248,7 +249,7 @@ impl Lua {
             ffi::luaL_loadstring as _,
             ffi::luaL_openlibs as _,
         ]);
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
         {
             _symbols.push(ffi::lua_getglobal as _);
             _symbols.push(ffi::lua_setglobal as _);
@@ -336,6 +337,39 @@ impl Lua {
         R::from_stack_multi(nresults, &lua)
     }
 
+    /// Runs callback with the inner RawLua value. It can be used to manually push and get values on
+    /// the stack.
+    ///
+    /// This function is safe because all unsafe actions with RawLua can only be done with unsafe
+    ///
+    /// # Example
+    /// ```
+    /// # use mlua::{Lua, Result, FromLua, IntoLua};
+    /// # fn main() -> Result<()> {
+    /// let lua = Lua::new();
+    /// let n: i32 = {
+    ///     let num = 11i32;
+    ///     lua.exec_raw_lua(|lua| {
+    ///         unsafe {
+    ///             <i32 as IntoLua>::push_into_stack(num, lua)?;
+    ///         }
+    ///
+    ///         let n = unsafe {
+    ///             <i32 as FromLua>::from_stack(-1, lua)?
+    ///         };
+    ///         Result::Ok(n)
+    ///     })
+    /// }?;
+    /// assert_eq!(n, 11);
+    /// # Ok(())
+    /// # }
+    /// ```
+    #[doc(hidden)]
+    pub fn exec_raw_lua<R>(&self, f: impl FnOnce(&RawLua) -> R) -> R {
+        let lua = self.lock();
+        f(&lua)
+    }
+
     /// Loads the specified subset of the standard libraries into an existing Lua state.
     ///
     /// Use the [`StdLib`] flags to specify the libraries you want to load.
@@ -358,6 +392,8 @@ impl Lua {
         if cfg!(feature = "luau") && !modname.starts_with('@') {
             return Err(Error::runtime("module name must begin with '@'"));
         }
+        #[cfg(feature = "luau")]
+        let modname = modname.to_ascii_lowercase();
         unsafe {
             self.exec_raw::<()>(value, |state| {
                 ffi::luaL_getsubtable(state, ffi::LUA_REGISTRYINDEX, LOADED_MODULES_KEY);
@@ -379,7 +415,7 @@ impl Lua {
     #[cfg(not(feature = "luau"))]
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn preload_module(&self, modname: &str, func: Function) -> Result<()> {
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
         let preload = unsafe {
             self.exec_raw::<Option<Table>>((), |state| {
                 ffi::lua_getfield(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_PRELOAD_TABLE);
@@ -486,6 +522,7 @@ impl Lua {
     /// - Set globals to read-only (and activates safeenv)
     /// - Setup local environment table that performs writes locally and proxies reads to the global
     ///   environment.
+    /// - Allow only `count` mode in `collectgarbage` function.
     ///
     /// # Examples
     ///
@@ -543,7 +580,7 @@ impl Lua {
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn set_global_hook<F>(&self, triggers: HookTriggers, callback: F) -> Result<()>
     where
-        F: Fn(&Lua, Debug) -> Result<VmState> + MaybeSend + 'static,
+        F: Fn(&Lua, &Debug) -> Result<VmState> + MaybeSend + 'static,
     {
         let lua = self.lock();
         unsafe {
@@ -576,7 +613,7 @@ impl Lua {
     /// # fn main() -> Result<()> {
     /// let lua = Lua::new();
     /// lua.set_hook(HookTriggers::EVERY_LINE, |_lua, debug| {
-    ///     println!("line {}", debug.curr_line());
+    ///     println!("line {:?}", debug.current_line());
     ///     Ok(VmState::Continue)
     /// });
     ///
@@ -593,7 +630,7 @@ impl Lua {
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn set_hook<F>(&self, triggers: HookTriggers, callback: F) -> Result<()>
     where
-        F: Fn(&Lua, Debug) -> Result<VmState> + MaybeSend + 'static,
+        F: Fn(&Lua, &Debug) -> Result<VmState> + MaybeSend + 'static,
     {
         let lua = self.lock();
         unsafe { lua.set_thread_hook(lua.state(), HookKind::Thread(triggers, XRc::new(callback))) }
@@ -628,13 +665,13 @@ impl Lua {
     ///
     /// Any Luau code is guaranteed to call this handler "eventually"
     /// (in practice this can happen at any function call or at any loop iteration).
+    /// This is similar to `Lua::set_hook` but in more simplified form.
     ///
     /// The provided interrupt function can error, and this error will be propagated through
     /// the Luau code that was executing at the time the interrupt was triggered.
     /// Also this can be used to implement continuous execution limits by instructing Luau VM to
-    /// yield by returning [`VmState::Yield`].
-    ///
-    /// This is similar to `Lua::set_hook` but in more simplified form.
+    /// yield by returning [`VmState::Yield`]. The yield will happen only at yieldable points
+    /// of execution (not across metamethod/C-call boundaries).
     ///
     /// # Example
     ///
@@ -692,7 +729,10 @@ impl Lua {
             match result {
                 VmState::Continue => {}
                 VmState::Yield => {
-                    ffi::lua_yield(state, 0);
+                    // We can yield only at yieldable points, otherwise ignore and continue
+                    if ffi::lua_isyieldable(state) != 0 {
+                        ffi::lua_yield(state, 0);
+                    }
                 }
             }
         }
@@ -807,8 +847,8 @@ impl Lua {
     }
 
     /// Sets the warning function to be used by Lua to emit warnings.
-    #[cfg(feature = "lua54")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
     pub fn set_warning_function<F>(&self, callback: F)
     where
         F: Fn(&Lua, &str, bool) -> Result<()> + MaybeSend + 'static,
@@ -840,8 +880,8 @@ impl Lua {
     /// Removes warning function previously set by `set_warning_function`.
     ///
     /// This function has no effect if a warning function was not previously set.
-    #[cfg(feature = "lua54")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
     pub fn remove_warning_function(&self) {
         let lua = self.lock();
         unsafe {
@@ -854,8 +894,8 @@ impl Lua {
     ///
     /// A message in a call with `incomplete` set to `true` should be continued in
     /// another call to this function.
-    #[cfg(feature = "lua54")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
     pub fn warning(&self, msg: impl AsRef<str>, incomplete: bool) {
         let msg = msg.as_ref();
         let mut bytes = vec![0; msg.len() + 1];
@@ -868,18 +908,16 @@ impl Lua {
         }
     }
 
-    /// Gets information about the interpreter runtime stack.
+    /// Gets information about the interpreter runtime stack at the given level.
     ///
-    /// This function returns [`Debug`] structure that can be used to get information about the
-    /// function executing at a given level. Level `0` is the current running function, whereas
-    /// level `n+1` is the function that has called level `n` (except for tail calls, which do
-    /// not count in the stack).
-    ///
-    /// [`Debug`]: crate::hook::Debug
-    pub fn inspect_stack(&self, level: usize) -> Option<Debug> {
+    /// This function calls callback `f`, passing the [`Debug`] structure that can be used to get
+    /// information about the function executing at a given level.
+    /// Level `0` is the current running function, whereas level `n+1` is the function that has
+    /// called level `n` (except for tail calls, which do not count in the stack).
+    pub fn inspect_stack<R>(&self, level: usize, f: impl FnOnce(&Debug) -> R) -> Option<R> {
         let lua = self.lock();
         unsafe {
-            let mut ar: ffi::lua_Debug = mem::zeroed();
+            let mut ar = mem::zeroed::<ffi::lua_Debug>();
             let level = level as c_int;
             #[cfg(not(feature = "luau"))]
             if ffi::lua_getstack(lua.state(), level, &mut ar) == 0 {
@@ -889,7 +927,28 @@ impl Lua {
             if ffi::lua_getinfo(lua.state(), level, cstr!(""), &mut ar) == 0 {
                 return None;
             }
-            Some(Debug::new_owned(lua, level, ar))
+
+            Some(f(&Debug::new(&lua, level, &mut ar)))
+        }
+    }
+
+    /// Creates a traceback of the call stack at the given level.
+    ///
+    /// The `msg` parameter, if provided, is added at the beginning of the traceback.
+    /// The `level` parameter works the same way as in [`Lua::inspect_stack`].
+    pub fn traceback(&self, msg: Option<&str>, level: usize) -> Result<String> {
+        let lua = self.lock();
+        unsafe {
+            check_stack(lua.state(), 3)?;
+            protect_lua!(lua.state(), 0, 1, |state| {
+                let msg = match msg {
+                    Some(s) => ffi::lua_pushlstring(state, s.as_ptr() as *const c_char, s.len()),
+                    None => ptr::null(),
+                };
+                // `protect_lua` adds it's own call frame, so we need to increase level by 1
+                ffi::luaL_traceback(state, state, msg, (level + 1) as c_int);
+            })?;
+            Ok(String(lua.pop_ref()))
         }
     }
 
@@ -928,7 +987,13 @@ impl Lua {
     }
 
     /// Returns `true` if the garbage collector is currently running automatically.
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau"))]
+    #[cfg(any(
+        feature = "lua55",
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luau"
+    ))]
     pub fn gc_is_running(&self) -> bool {
         let lua = self.lock();
         unsafe { ffi::lua_gc(lua.main_state(), ffi::LUA_GCISRUNNING, 0) != 0 }
@@ -993,8 +1058,12 @@ impl Lua {
         let lua = self.lock();
         let state = lua.main_state();
         unsafe {
-            #[cfg(not(feature = "luau"))]
+            #[cfg(feature = "lua55")]
+            return ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPPAUSE, pause);
+
+            #[cfg(not(any(feature = "lua55", feature = "luau")))]
             return ffi::lua_gc(state, ffi::LUA_GCSETPAUSE, pause);
+
             #[cfg(feature = "luau")]
             return ffi::lua_gc(state, ffi::LUA_GCSETGOAL, pause);
         }
@@ -1008,7 +1077,18 @@ impl Lua {
     /// [documentation]: https://www.lua.org/manual/5.4/manual.html#2.5
     pub fn gc_set_step_multiplier(&self, step_multiplier: c_int) -> c_int {
         let lua = self.lock();
-        unsafe { ffi::lua_gc(lua.main_state(), ffi::LUA_GCSETSTEPMUL, step_multiplier) }
+        unsafe {
+            #[cfg(feature = "lua55")]
+            return ffi::lua_gc(
+                lua.main_state(),
+                ffi::LUA_GCPARAM,
+                ffi::LUA_GCPSTEPMUL,
+                step_multiplier,
+            );
+
+            #[cfg(not(feature = "lua55"))]
+            return ffi::lua_gc(lua.main_state(), ffi::LUA_GCSETSTEPMUL, step_multiplier);
+        }
     }
 
     /// Changes the collector to incremental mode with the given parameters.
@@ -1047,12 +1127,19 @@ impl Lua {
             #[cfg(not(feature = "luau"))]
             let _ = step_size; // Ignored
 
-            GCMode::Incremental
+            return GCMode::Incremental;
         }
 
+        #[cfg(feature = "lua55")]
+        let prev_mode = unsafe {
+            ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPPAUSE, pause);
+            ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPSTEPMUL, step_multiplier);
+            ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPSTEPSIZE, step_size);
+            ffi::lua_gc(state, ffi::LUA_GCINC)
+        };
         #[cfg(feature = "lua54")]
         let prev_mode = unsafe { ffi::lua_gc(state, ffi::LUA_GCINC, pause, step_multiplier, step_size) };
-        #[cfg(feature = "lua54")]
+        #[cfg(any(feature = "lua55", feature = "lua54"))]
         match prev_mode {
             ffi::LUA_GCINC => GCMode::Incremental,
             ffi::LUA_GCGEN => GCMode::Generational,
@@ -1066,11 +1153,19 @@ impl Lua {
     /// can be found in the Lua 5.4 [documentation][lua_doc].
     ///
     /// [lua_doc]: https://www.lua.org/manual/5.4/manual.html#2.5.2
-    #[cfg(feature = "lua54")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
     pub fn gc_gen(&self, minor_multiplier: c_int, major_multiplier: c_int) -> GCMode {
         let lua = self.lock();
         let state = lua.main_state();
+        #[cfg(feature = "lua55")]
+        let prev_mode = unsafe {
+            ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPMINORMUL, minor_multiplier);
+            ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPMINORMAJOR, major_multiplier);
+            // TODO: LUA_GCPMAJORMINOR
+            ffi::lua_gc(state, ffi::LUA_GCGEN)
+        };
+        #[cfg(not(feature = "lua55"))]
         let prev_mode = unsafe { ffi::lua_gc(state, ffi::LUA_GCGEN, minor_multiplier, major_multiplier) };
         match prev_mode {
             ffi::LUA_GCGEN => GCMode::Generational,
@@ -1148,36 +1243,52 @@ impl Lua {
         }
     }
 
-    /// Create and return an interned Lua string.
+    /// Creates and returns an interned Lua string.
     ///
     /// Lua strings can be arbitrary `[u8]` data including embedded nulls, so in addition to `&str`
     /// and `&String`, you can also pass plain `&[u8]` here.
     #[inline]
     pub fn create_string(&self, s: impl AsRef<[u8]>) -> Result<String> {
-        unsafe { self.lock().create_string(s) }
+        unsafe { self.lock().create_string(s.as_ref()) }
     }
 
-    /// Create and return a Luau [buffer] object from a byte slice of data.
+    /// Creates and returns an external Lua string.
+    ///
+    /// External string is a string where the memory is managed by Rust code, and Lua only holds a
+    /// reference to it. This can be used to avoid copying large strings into Lua memory.
+    #[cfg(feature = "lua55")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "lua55")))]
+    #[inline]
+    pub fn create_external_string(&self, s: impl Into<Vec<u8>>) -> Result<String> {
+        unsafe { self.lock().create_external_string(s.into()) }
+    }
+
+    /// Creates and returns a Luau [buffer] object from a byte slice of data.
     ///
     /// [buffer]: https://luau.org/library#buffer-library
     #[cfg(any(feature = "luau", doc))]
     #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
-    pub fn create_buffer(&self, buf: impl AsRef<[u8]>) -> Result<Buffer> {
+    pub fn create_buffer(&self, data: impl AsRef<[u8]>) -> Result<Buffer> {
         let lua = self.lock();
-        let state = lua.state();
+        let data = data.as_ref();
         unsafe {
-            if lua.unlikely_memory_error() {
-                crate::util::push_buffer(state, buf.as_ref(), false)?;
-                return Ok(Buffer(lua.pop_ref()));
-            }
-
-            let _sg = StackGuard::new(state);
-            check_stack(state, 3)?;
-            crate::util::push_buffer(state, buf.as_ref(), true)?;
-            Ok(Buffer(lua.pop_ref()))
+            let (ptr, buffer) = lua.create_buffer_with_capacity(data.len())?;
+            ptr.copy_from_nonoverlapping(data.as_ptr(), data.len());
+            Ok(buffer)
         }
     }
 
+    /// Creates and returns a Luau [buffer] object with the specified size.
+    ///
+    /// Size limit is 1GB. All bytes will be initialized to zero.
+    ///
+    /// [buffer]: https://luau.org/library#buffer-library
+    #[cfg(any(feature = "luau", doc))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub fn create_buffer_with_capacity(&self, size: usize) -> Result<Buffer> {
+        unsafe { Ok(self.lock().create_buffer_with_capacity(size)?.1) }
+    }
+
     /// Creates and returns a new empty table.
     #[inline]
     pub fn create_table(&self) -> Result<Table> {
@@ -1286,8 +1397,29 @@ impl Lua {
     /// This function is unsafe because provides a way to execute unsafe C function.
     pub unsafe fn create_c_function(&self, func: ffi::lua_CFunction) -> Result<Function> {
         let lua = self.lock();
-        ffi::lua_pushcfunction(lua.ref_thread(), func);
-        Ok(Function(lua.pop_ref_thread()))
+        if cfg!(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52"
+        )) {
+            ffi::lua_pushcfunction(lua.ref_thread(), func);
+            return Ok(Function(lua.pop_ref_thread()));
+        }
+
+        // Lua <5.2 requires memory allocation to push a C function
+        let state = lua.state();
+        {
+            let _sg = StackGuard::new(state);
+            check_stack(state, 3)?;
+
+            if lua.unlikely_memory_error() {
+                ffi::lua_pushcfunction(state, func);
+            } else {
+                protect_lua!(state, 0, 1, |state| ffi::lua_pushcfunction(state, func))?;
+            }
+            Ok(Function(lua.pop_ref()))
+        }
     }
 
     /// Wraps a Rust async function or closure, creating a callable Lua function handle to it.
@@ -1416,7 +1548,7 @@ impl Lua {
         let lua = self.lock();
         unsafe {
             // Deregister the type if it already registered
-            if let Some(&table_id) = (*lua.extra.get()).registered_userdata_t.get(&type_id) {
+            if let Some(table_id) = (*lua.extra.get()).registered_userdata_t.remove(&type_id) {
                 ffi::luaL_unref(lua.state(), ffi::LUA_REGISTRYINDEX, table_id);
             }
 
@@ -1467,7 +1599,27 @@ impl Lua {
         unsafe { self.lock().make_userdata(UserDataStorage::new(ud)) }
     }
 
-    /// Sets the metatable for a Lua builtin type.
+    /// Gets the metatable of a Lua built-in (primitive) type.
+    ///
+    /// The metatable is shared by all values of the given type.
+    ///
+    /// See [`Lua::set_type_metatable`] for examples.
+    #[allow(private_bounds)]
+    pub fn type_metatable<T: LuaType>(&self) -> Option<Table> {
+        let lua = self.lock();
+        let state = lua.state();
+        unsafe {
+            let _sg = StackGuard::new(state);
+            assert_stack(state, 2);
+
+            if lua.push_primitive_type::<T>() && ffi::lua_getmetatable(state, -1) != 0 {
+                return Some(Table(lua.pop_ref()));
+            }
+        }
+        None
+    }
+
+    /// Sets the metatable for a Lua built-in (primitive) type.
     ///
     /// The metatable will be shared by all values of the given type.
     ///
@@ -1494,44 +1646,13 @@ impl Lua {
             let _sg = StackGuard::new(state);
             assert_stack(state, 2);
 
-            match T::TYPE_ID {
-                ffi::LUA_TBOOLEAN => {
-                    ffi::lua_pushboolean(state, 0);
+            if lua.push_primitive_type::<T>() {
+                match metatable {
+                    Some(metatable) => lua.push_ref(&metatable.0),
+                    None => ffi::lua_pushnil(state),
                 }
-                ffi::LUA_TLIGHTUSERDATA => {
-                    ffi::lua_pushlightuserdata(state, ptr::null_mut());
-                }
-                ffi::LUA_TNUMBER => {
-                    ffi::lua_pushnumber(state, 0.);
-                }
-                #[cfg(feature = "luau")]
-                ffi::LUA_TVECTOR => {
-                    #[cfg(not(feature = "luau-vector4"))]
-                    ffi::lua_pushvector(state, 0., 0., 0.);
-                    #[cfg(feature = "luau-vector4")]
-                    ffi::lua_pushvector(state, 0., 0., 0., 0.);
-                }
-                ffi::LUA_TSTRING => {
-                    ffi::lua_pushstring(state, b"\0" as *const u8 as *const _);
-                }
-                ffi::LUA_TFUNCTION => match self.load("function() end").eval::<Function>() {
-                    Ok(func) => lua.push_ref(&func.0),
-                    Err(_) => return,
-                },
-                ffi::LUA_TTHREAD => {
-                    ffi::lua_pushthread(state);
-                }
-                #[cfg(feature = "luau")]
-                ffi::LUA_TBUFFER => {
-                    ffi::lua_newbuffer(state, 0);
-                }
-                _ => return,
+                ffi::lua_setmetatable(state, -2);
             }
-            match metatable {
-                Some(metatable) => lua.push_ref(&metatable.0),
-                None => ffi::lua_pushnil(state),
-            }
-            ffi::lua_setmetatable(state, -2);
         }
     }
 
@@ -1542,7 +1663,7 @@ impl Lua {
         unsafe {
             let _sg = StackGuard::new(state);
             assert_stack(state, 1);
-            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
             ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_RIDX_GLOBALS);
             #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
             ffi::lua_pushvalue(state, ffi::LUA_GLOBALSINDEX);
@@ -1550,6 +1671,39 @@ impl Lua {
         }
     }
 
+    /// Sets the global environment.
+    ///
+    /// This will replace the current global environment with the provided `globals` table.
+    ///
+    /// For Lua 5.2+ the globals table is stored in the registry and shared between all threads.
+    /// For Lua 5.1 and Luau the globals table is stored in each thread.
+    ///
+    /// Please note that any existing Lua functions have cached global environment and will not
+    /// see the changes made by this method.
+    /// To update the environment for existing Lua functions, use [`Function::set_environment`].
+    pub fn set_globals(&self, globals: Table) -> Result<()> {
+        let lua = self.lock();
+        let state = lua.state();
+        unsafe {
+            #[cfg(feature = "luau")]
+            if (*lua.extra.get()).sandboxed {
+                return Err(Error::runtime("cannot change globals in a sandboxed Lua state"));
+            }
+
+            let _sg = StackGuard::new(state);
+            check_stack(state, 1)?;
+
+            lua.push_ref(&globals.0);
+
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
+            ffi::lua_rawseti(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_RIDX_GLOBALS);
+            #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
+            ffi::lua_replace(state, ffi::LUA_GLOBALSINDEX);
+        }
+
+        Ok(())
+    }
+
     /// Returns a handle to the active `Thread`.
     ///
     /// For calls to `Lua` this will be the main Lua thread, for parameters given to a callback,
@@ -1955,7 +2109,7 @@ impl Lua {
     /// Panics if the data object of type `T` is currently mutably borrowed. Multiple immutable
     /// reads can be taken out at the same time.
     #[track_caller]
-    pub fn app_data_ref<T: 'static>(&self) -> Option<AppDataRef<T>> {
+    pub fn app_data_ref<T: 'static>(&self) -> Option<AppDataRef<'_, T>> {
         let guard = self.lock_arc();
         let extra = unsafe { &*guard.extra.get() };
         extra.app_data.borrow(Some(guard))
@@ -1963,7 +2117,7 @@ impl Lua {
 
     /// Tries to get a reference to an application data object stored by [`Lua::set_app_data`] of
     /// type `T`.
-    pub fn try_app_data_ref<T: 'static>(&self) -> StdResult<Option<AppDataRef<T>>, BorrowError> {
+    pub fn try_app_data_ref<T: 'static>(&self) -> StdResult<Option<AppDataRef<'_, T>>, BorrowError> {
         let guard = self.lock_arc();
         let extra = unsafe { &*guard.extra.get() };
         extra.app_data.try_borrow(Some(guard))
@@ -1976,7 +2130,7 @@ impl Lua {
     ///
     /// Panics if the data object of type `T` is currently borrowed.
     #[track_caller]
-    pub fn app_data_mut<T: 'static>(&self) -> Option<AppDataRefMut<T>> {
+    pub fn app_data_mut<T: 'static>(&self) -> Option<AppDataRefMut<'_, T>> {
         let guard = self.lock_arc();
         let extra = unsafe { &*guard.extra.get() };
         extra.app_data.borrow_mut(Some(guard))
@@ -1984,7 +2138,7 @@ impl Lua {
 
     /// Tries to get a mutable reference to an application data object stored by
     /// [`Lua::set_app_data`] of type `T`.
-    pub fn try_app_data_mut<T: 'static>(&self) -> StdResult<Option<AppDataRefMut<T>>, BorrowMutError> {
+    pub fn try_app_data_mut<T: 'static>(&self) -> StdResult<Option<AppDataRefMut<'_, T>>, BorrowMutError> {
         let guard = self.lock_arc();
         let extra = unsafe { &*guard.extra.get() };
         extra.app_data.try_borrow_mut(Some(guard))
@@ -2020,6 +2174,105 @@ impl Lua {
         LightUserData(&ASYNC_POLL_TERMINATE as *const u8 as *mut std::os::raw::c_void)
     }
 
+    #[cfg(feature = "async")]
+    #[inline(always)]
+    pub(crate) fn poll_yield() -> LightUserData {
+        static ASYNC_POLL_YIELD: u8 = 0;
+        LightUserData(&ASYNC_POLL_YIELD as *const u8 as *mut std::os::raw::c_void)
+    }
+
+    /// Suspends the current async function, returning the provided arguments to caller.
+    ///
+    /// This function is similar to [`coroutine.yield`] but allow yielding Rust functions
+    /// and passing values to the caller.
+    /// Please note that you cannot cross [`Thread`] boundaries (e.g. calling `yield_with` on one
+    /// thread and resuming on another).
+    ///
+    /// # Examples
+    ///
+    /// Async iterator:
+    ///
+    /// ```
+    /// # use mlua::{Lua, Result};
+    /// #
+    /// async fn generator(lua: Lua, _: ()) -> Result<()> {
+    ///     for i in 0..10 {
+    ///         lua.yield_with::<()>(i).await?;
+    ///     }
+    ///     Ok(())
+    /// }
+    ///
+    /// fn main() -> Result<()> {
+    ///     let lua = Lua::new();
+    ///     lua.globals().set("generator", lua.create_async_function(generator)?)?;
+    ///
+    ///     lua.load(r#"
+    ///        local n = 0
+    ///        for i in coroutine.wrap(generator) do
+    ///            n = n + i
+    ///        end
+    ///        assert(n == 45)
+    ///     "#)
+    ///     .exec()
+    /// }
+    /// ```
+    ///
+    /// Exchange values on yield:
+    ///
+    /// ```
+    /// # use mlua::{Lua, Result, Value};
+    /// #
+    /// async fn pingpong(lua: Lua, mut val: i32) -> Result<()> {
+    ///     loop {
+    ///         val = lua.yield_with::<i32>(val).await? + 1;
+    ///     }
+    ///     Ok(())
+    /// }
+    ///
+    /// # fn main() -> Result<()> {
+    /// let lua = Lua::new();
+    ///
+    /// let co = lua.create_thread(lua.create_async_function(pingpong)?)?;
+    /// assert_eq!(co.resume::<i32>(1)?, 1);
+    /// assert_eq!(co.resume::<i32>(2)?, 3);
+    /// assert_eq!(co.resume::<i32>(3)?, 4);
+    ///
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`coroutine.yield`]: https://www.lua.org/manual/5.4/manual.html#pdf-coroutine.yield
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    pub async fn yield_with<R: FromLuaMulti>(&self, args: impl IntoLuaMulti) -> Result<R> {
+        let mut args = Some(args.into_lua_multi(self)?);
+        future::poll_fn(move |_cx| match args.take() {
+            Some(args) => unsafe {
+                let lua = self.lock();
+                lua.push(Self::poll_yield())?; // yield marker
+                if args.len() <= 1 {
+                    lua.push(args.front())?;
+                } else {
+                    lua.push(lua.create_sequence_from(&args)?)?;
+                }
+                lua.push(args.len())?;
+                Poll::Pending
+            },
+            None => unsafe {
+                let lua = self.lock();
+                let state = lua.state();
+                let top = ffi::lua_gettop(state);
+                if top == 0 || ffi::lua_type(state, 1) != ffi::LUA_TUSERDATA {
+                    // This must be impossible scenario if used correctly
+                    return Poll::Ready(R::from_stack_multi(0, &lua));
+                }
+                let _sg = StackGuard::with_top(state, 1);
+                Poll::Ready(R::from_stack_multi(top - 1, &lua))
+            },
+        })
+        .await
+    }
+
     /// Returns a weak reference to the Lua instance.
     ///
     /// This is useful for creating a reference to the Lua instance that does not prevent it from
@@ -2029,7 +2282,6 @@ impl Lua {
         WeakLua(XRc::downgrade(&self.raw))
     }
 
-    // Luau version located in `luau/mod.rs`
     #[cfg(not(feature = "luau"))]
     fn disable_c_modules(&self) -> Result<()> {
         let package: Table = self.globals().get("package")?;
@@ -2043,7 +2295,7 @@ impl Lua {
             })?,
         )?;
 
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
         let searchers: Table = package.get("searchers")?;
         #[cfg(any(feature = "lua51", feature = "luajit"))]
         let searchers: Table = package.get("loaders")?;
@@ -2052,13 +2304,15 @@ impl Lua {
 
         // The third and fourth searchers looks for a loader as a C library
         searchers.raw_set(3, loader)?;
-        searchers.raw_remove(4)?;
+        if searchers.raw_len() >= 4 {
+            searchers.raw_remove(4)?;
+        }
 
         Ok(())
     }
 
     #[inline(always)]
-    pub(crate) fn lock(&self) -> ReentrantMutexGuard<RawLua> {
+    pub(crate) fn lock(&self) -> ReentrantMutexGuard<'_, RawLua> {
         let rawlua = self.raw.lock();
         #[cfg(feature = "luau")]
         if unsafe { (*rawlua.extra.get()).running_gc } {

src/state/extra.rs

@@ -28,7 +28,7 @@ use super::{Lua, WeakLua};
 static EXTRA_REGISTRY_KEY: u8 = 0;
 
 const WRAPPED_FAILURE_POOL_DEFAULT_CAPACITY: usize = 64;
-const REF_STACK_RESERVE: c_int = 2;
+const REF_STACK_RESERVE: c_int = 3;
 
 /// Data associated with the Lua state.
 pub(crate) struct ExtraData {
@@ -64,7 +64,7 @@ pub(crate) struct ExtraData {
     pub(super) wrapped_failure_top: usize,
     // Pool of `Thread`s (coroutines) for async execution
     #[cfg(feature = "async")]
-    pub(super) thread_pool: Vec<c_int>,
+    pub(super) thread_pool: Vec<crate::types::ValueRefIndex>,
 
     // Address of `WrappedFailure` metatable
     pub(super) wrapped_failure_mt_ptr: *const c_void,
@@ -76,8 +76,8 @@ pub(crate) struct ExtraData {
     #[cfg(not(feature = "luau"))]
     pub(super) hook_callback: Option<crate::types::HookCallback>,
     #[cfg(not(feature = "luau"))]
-    pub(super) hook_triggers: crate::hook::HookTriggers,
-    #[cfg(feature = "lua54")]
+    pub(super) hook_triggers: crate::debug::HookTriggers,
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
     pub(super) warn_callback: Option<crate::types::WarnCallback>,
     #[cfg(feature = "luau")]
     pub(super) interrupt_callback: Option<crate::types::InterruptCallback>,
@@ -89,11 +89,13 @@ pub(crate) struct ExtraData {
     #[cfg(feature = "luau")]
     pub(crate) running_gc: bool,
     #[cfg(feature = "luau")]
-    pub(super) sandboxed: bool,
+    pub(crate) sandboxed: bool,
     #[cfg(feature = "luau")]
     pub(super) compiler: Option<Compiler>,
     #[cfg(feature = "luau-jit")]
     pub(super) enable_jit: bool,
+    #[cfg(feature = "luau")]
+    pub(crate) mem_categories: Vec<std::ffi::CString>,
 }
 
 impl Drop for ExtraData {
@@ -180,7 +182,7 @@ impl ExtraData {
             hook_callback: None,
             #[cfg(not(feature = "luau"))]
             hook_triggers: Default::default(),
-            #[cfg(feature = "lua54")]
+            #[cfg(any(feature = "lua55", feature = "lua54"))]
             warn_callback: None,
             #[cfg(feature = "luau")]
             interrupt_callback: None,
@@ -196,6 +198,8 @@ impl ExtraData {
             enable_jit: true,
             #[cfg(feature = "luau")]
             running_gc: false,
+            #[cfg(feature = "luau")]
+            mem_categories: vec![std::ffi::CString::new("main").unwrap()],
         }));
 
         // Store it in the registry
@@ -212,7 +216,7 @@ impl ExtraData {
         self.weak.write(WeakLua(XRc::downgrade(raw)));
     }
 
-    pub(super) unsafe fn get(state: *mut ffi::lua_State) -> *mut Self {
+    pub(crate) unsafe fn get(state: *mut ffi::lua_State) -> *mut Self {
         #[cfg(feature = "luau")]
         if cfg!(not(feature = "module")) {
             // In the main app we can use `lua_callbacks` to access ExtraData
@@ -259,4 +263,32 @@ impl ExtraData {
     pub(super) unsafe fn weak(&self) -> &WeakLua {
         self.weak.assume_init_ref()
     }
+
+    /// Pops a reference from top of the auxiliary stack and move it to a first free slot.
+    pub(super) unsafe fn ref_stack_pop(&mut self) -> c_int {
+        if let Some(free) = self.ref_free.pop() {
+            ffi::lua_replace(self.ref_thread, free);
+            return free;
+        }
+
+        // Try to grow max stack size
+        if self.ref_stack_top >= self.ref_stack_size {
+            let mut inc = self.ref_stack_size; // Try to double stack size
+            while inc > 0 && ffi::lua_checkstack(self.ref_thread, inc + REF_STACK_RESERVE) == 0 {
+                inc /= 2;
+            }
+            if inc == 0 {
+                // Pop item on top of the stack to avoid stack leaking and successfully run destructors
+                // during unwinding.
+                ffi::lua_pop(self.ref_thread, 1);
+                let top = self.ref_stack_top;
+                // It is a user error to create too many references to exhaust the Lua max stack size
+                // for the ref thread.
+                panic!("cannot create a Lua reference, out of auxiliary stack space (used {top} slots)");
+            }
+            self.ref_stack_size += inc;
+        }
+        self.ref_stack_top += 1;
+        self.ref_stack_top
+    }
 }

src/state/raw.rs

@@ -11,7 +11,7 @@ use crate::chunk::ChunkMode;
 use crate::error::{Error, Result};
 use crate::function::Function;
 use crate::memory::{MemoryState, ALLOCATOR};
-use crate::state::util::{callback_error_ext, ref_stack_pop};
+use crate::state::util::callback_error_ext;
 use crate::stdlib::StdLib;
 use crate::string::String;
 use crate::table::Table;
@@ -19,7 +19,7 @@ use crate::thread::Thread;
 use crate::traits::IntoLua;
 use crate::types::{
     AppDataRef, AppDataRefMut, Callback, CallbackUpvalue, DestructedUserdata, Integer, LightUserData,
-    MaybeSend, ReentrantMutex, RegistryKey, ValueRef, XRc,
+    LuaType, MaybeSend, ReentrantMutex, RegistryKey, ValueRef, XRc,
 };
 use crate::userdata::{
     init_userdata_metatable, AnyUserData, MetaMethod, RawUserDataRegistry, UserData, UserDataRegistry,
@@ -28,8 +28,8 @@ use crate::userdata::{
 use crate::util::{
     assert_stack, check_stack, get_destructed_userdata_metatable, get_internal_userdata, get_main_state,
     get_metatable_ptr, get_userdata, init_error_registry, init_internal_metatable, pop_error,
-    push_internal_userdata, push_string, push_table, rawset_field, safe_pcall, safe_xpcall, short_type_name,
-    StackGuard, WrappedFailure,
+    push_internal_userdata, push_string, push_table, push_userdata, rawset_field, safe_pcall, safe_xpcall,
+    short_type_name, StackGuard, WrappedFailure,
 };
 use crate::value::{Nil, Value};
 
@@ -38,7 +38,7 @@ use super::{Lua, LuaOptions, WeakLua};
 
 #[cfg(not(feature = "luau"))]
 use crate::{
-    hook::Debug,
+    debug::Debug,
     types::{HookCallback, HookKind, VmState},
 };
 
@@ -122,6 +122,12 @@ impl RawLua {
 
     pub(super) unsafe fn new(libs: StdLib, options: &LuaOptions) -> XRc<ReentrantMutex<Self>> {
         let mem_state: *mut MemoryState = Box::into_raw(Box::default());
+        #[cfg(feature = "lua55")]
+        let mut state = {
+            let seed = ffi::luaL_makeseed(ptr::null_mut());
+            ffi::lua_newstate(ALLOCATOR, mem_state as *mut c_void, seed)
+        };
+        #[cfg(not(feature = "lua55"))]
         let mut state = ffi::lua_newstate(ALLOCATOR, mem_state as *mut c_void);
         // If state is null then switch to Lua internal allocator
         if state.is_null() {
@@ -153,7 +159,7 @@ impl RawLua {
                 (|| -> Result<()> {
                     let _sg = StackGuard::new(state);
 
-                    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+                    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
                     ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_RIDX_GLOBALS);
                     #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
                     ffi::lua_pushvalue(state, ffi::LUA_GLOBALSINDEX);
@@ -296,7 +302,7 @@ impl RawLua {
         if is_safe {
             let curr_libs = (*self.extra.get()).libs;
             if (curr_libs ^ (curr_libs | libs)).contains(StdLib::PACKAGE) {
-                mlua_expect!(self.lua().disable_c_modules(), "Error during disabling C modules");
+                mlua_expect!(self.lua().disable_c_modules(), "Error disabling C modules");
             }
         }
         #[cfg(feature = "luau")]
@@ -316,7 +322,7 @@ impl RawLua {
     /// Private version of [`Lua::app_data_ref`]
     #[track_caller]
     #[inline]
-    pub(crate) fn priv_app_data_ref<T: 'static>(&self) -> Option<AppDataRef<T>> {
+    pub(crate) fn priv_app_data_ref<T: 'static>(&self) -> Option<AppDataRef<'_, T>> {
         let extra = unsafe { &*self.extra.get() };
         extra.app_data_priv.borrow(None)
     }
@@ -324,7 +330,7 @@ impl RawLua {
     /// Private version of [`Lua::app_data_mut`]
     #[track_caller]
     #[inline]
-    pub(crate) fn priv_app_data_mut<T: 'static>(&self) -> Option<AppDataRefMut<T>> {
+    pub(crate) fn priv_app_data_mut<T: 'static>(&self) -> Option<AppDataRefMut<'_, T>> {
         let extra = unsafe { &*self.extra.get() };
         extra.app_data_priv.borrow_mut(None)
     }
@@ -416,7 +422,7 @@ impl RawLua {
                 VmState::Yield => {
                     // Only count and line events can yield
                     if event == ffi::LUA_HOOKCOUNT || event == ffi::LUA_HOOKLINE {
-                        #[cfg(any(feature = "lua54", feature = "lua53"))]
+                        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
                         if ffi::lua_isyieldable(state) != 0 {
                             ffi::lua_yield(state, 0);
                         }
@@ -435,8 +441,8 @@ impl RawLua {
                 match (*extra).hook_callback.clone() {
                     Some(hook_callback) => {
                         let rawlua = (*extra).raw_lua();
-                        let debug = Debug::new(rawlua, ar);
-                        hook_callback((*extra).lua(), debug)
+                        let debug = Debug::new(rawlua, 0, ar);
+                        hook_callback((*extra).lua(), &debug)
                     }
                     None => {
                         ffi::lua_sethook(state, None, 0, 0);
@@ -465,9 +471,9 @@ impl RawLua {
 
             let status = callback_error_ext(state, ptr::null_mut(), false, |extra, _| {
                 let rawlua = (*extra).raw_lua();
-                let debug = Debug::new(rawlua, ar);
+                let debug = Debug::new(rawlua, 0, ar);
                 let hook_callback = (*hook_callback_ptr).clone();
-                hook_callback((*extra).lua(), debug)
+                hook_callback((*extra).lua(), &debug)
             });
             process_status(state, (*ar).event, status)
         }
@@ -510,19 +516,50 @@ impl RawLua {
     }
 
     /// See [`Lua::create_string`]
-    pub(crate) unsafe fn create_string(&self, s: impl AsRef<[u8]>) -> Result<String> {
+    pub(crate) unsafe fn create_string(&self, s: &[u8]) -> Result<String> {
         let state = self.state();
         if self.unlikely_memory_error() {
-            push_string(state, s.as_ref(), false)?;
+            push_string(state, s, false)?;
             return Ok(String(self.pop_ref()));
         }
 
         let _sg = StackGuard::new(state);
         check_stack(state, 3)?;
-        push_string(state, s.as_ref(), true)?;
+        push_string(state, s, true)?;
         Ok(String(self.pop_ref()))
     }
 
+    /// Creates an external string, that is, a string that uses memory not managed by Lua.
+    ///
+    /// Modifies the input data to add `\0` terminator.
+    #[cfg(feature = "lua55")]
+    pub(crate) unsafe fn create_external_string(&self, bytes: Vec<u8>) -> Result<String> {
+        let state = self.state();
+        if self.unlikely_memory_error() {
+            crate::util::push_external_string(state, bytes, false)?;
+            return Ok(String(self.pop_ref()));
+        }
+
+        let _sg = StackGuard::new(state);
+        check_stack(state, 3)?;
+        crate::util::push_external_string(state, bytes, true)?;
+        Ok(String(self.pop_ref()))
+    }
+
+    #[cfg(feature = "luau")]
+    pub(crate) unsafe fn create_buffer_with_capacity(&self, size: usize) -> Result<(*mut u8, crate::Buffer)> {
+        let state = self.state();
+        if self.unlikely_memory_error() {
+            let ptr = crate::util::push_buffer(state, size, false)?;
+            return Ok((ptr, crate::Buffer(self.pop_ref())));
+        }
+
+        let _sg = StackGuard::new(state);
+        check_stack(state, 3)?;
+        let ptr = crate::util::push_buffer(state, size, true)?;
+        Ok((ptr, crate::Buffer(self.pop_ref())))
+    }
+
     /// See [`Lua::create_table_with_capacity`]
     pub(crate) unsafe fn create_table_with_capacity(&self, narr: usize, nrec: usize) -> Result<Table> {
         let state = self.state();
@@ -624,7 +661,7 @@ impl RawLua {
     #[cfg(feature = "async")]
     pub(crate) unsafe fn create_recycled_thread(&self, func: &Function) -> Result<Thread> {
         if let Some(index) = (*self.extra.get()).thread_pool.pop() {
-            let thread_state = ffi::lua_tothread(self.ref_thread(), index);
+            let thread_state = ffi::lua_tothread(self.ref_thread(), *index.0);
             ffi::lua_xpush(self.ref_thread(), thread_state, func.0.index);
 
             #[cfg(feature = "luau")]
@@ -645,23 +682,64 @@ impl RawLua {
     pub(crate) unsafe fn recycle_thread(&self, thread: &mut Thread) {
         let extra = &mut *self.extra.get();
         if extra.thread_pool.len() < extra.thread_pool.capacity() {
-            extra.thread_pool.push(thread.0.index);
-            thread.0.drop = false; // Prevent thread from being garbage collected
+            if let Some(index) = thread.0.index_count.take() {
+                extra.thread_pool.push(index);
+            }
         }
     }
 
+    /// Pushes a primitive type value onto the Lua stack.
+    pub(crate) unsafe fn push_primitive_type<T: LuaType>(&self) -> bool {
+        match T::TYPE_ID {
+            ffi::LUA_TBOOLEAN => {
+                ffi::lua_pushboolean(self.state(), 0);
+            }
+            ffi::LUA_TLIGHTUSERDATA => {
+                ffi::lua_pushlightuserdata(self.state(), ptr::null_mut());
+            }
+            ffi::LUA_TNUMBER => {
+                ffi::lua_pushnumber(self.state(), 0.);
+            }
+            #[cfg(feature = "luau")]
+            ffi::LUA_TVECTOR => {
+                #[cfg(not(feature = "luau-vector4"))]
+                ffi::lua_pushvector(self.state(), 0., 0., 0.);
+                #[cfg(feature = "luau-vector4")]
+                ffi::lua_pushvector(self.state(), 0., 0., 0., 0.);
+            }
+            ffi::LUA_TSTRING => {
+                ffi::lua_pushstring(self.state(), b"\0" as *const u8 as *const _);
+            }
+            ffi::LUA_TFUNCTION => {
+                unsafe extern "C-unwind" fn func(_state: *mut ffi::lua_State) -> c_int {
+                    0
+                }
+                ffi::lua_pushcfunction(self.state(), func);
+            }
+            ffi::LUA_TTHREAD => {
+                ffi::lua_pushthread(self.state());
+            }
+            #[cfg(feature = "luau")]
+            ffi::LUA_TBUFFER => {
+                ffi::lua_newbuffer(self.state(), 0);
+            }
+            _ => return false,
+        }
+        true
+    }
+
     /// Pushes a value that implements `IntoLua` onto the Lua stack.
     ///
     /// Uses up to 2 stack spaces to push a single value, does not call `checkstack`.
     #[inline(always)]
-    pub(crate) unsafe fn push(&self, value: impl IntoLua) -> Result<()> {
+    pub unsafe fn push(&self, value: impl IntoLua) -> Result<()> {
         value.push_into_stack(self)
     }
 
     /// Pushes a `Value` (by reference) onto the Lua stack.
     ///
     /// Uses 2 stack spaces, does not call `checkstack`.
-    pub(crate) unsafe fn push_value(&self, value: &Value) -> Result<()> {
+    pub unsafe fn push_value(&self, value: &Value) -> Result<()> {
         let state = self.state();
         match value {
             Value::Nil => ffi::lua_pushnil(state),
@@ -694,8 +772,9 @@ impl RawLua {
 
     /// Pops a value from the Lua stack.
     ///
-    /// Uses 2 stack spaces, does not call `checkstack`.
-    pub(crate) unsafe fn pop_value(&self) -> Value {
+    /// Uses up to 1 stack spaces, does not call `checkstack`.
+    #[inline]
+    pub unsafe fn pop_value(&self) -> Value {
         let value = self.stack_value(-1, None);
         ffi::lua_pop(self.state(), 1);
         value
@@ -703,7 +782,7 @@ impl RawLua {
 
     /// Returns value at given stack index without popping it.
     ///
-    /// Uses 2 stack spaces, does not call checkstack.
+    /// Uses up to 1 stack spaces, does not call `checkstack`.
     pub(crate) unsafe fn stack_value(&self, idx: c_int, type_hint: Option<c_int>) -> Value {
         let state = self.state();
         match type_hint.unwrap_or_else(|| ffi::lua_type(state, idx)) {
@@ -713,7 +792,7 @@ impl RawLua {
 
             ffi::LUA_TLIGHTUSERDATA => Value::LightUserData(LightUserData(ffi::lua_touserdata(state, idx))),
 
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             ffi::LUA_TNUMBER => {
                 if ffi::lua_isinteger(state, idx) != 0 {
                     Value::Integer(ffi::lua_tointeger(state, idx))
@@ -728,7 +807,7 @@ impl RawLua {
 
                 let n = ffi::lua_tonumber(state, idx);
                 match num_traits::cast(n) {
-                    Some(i) if (n - (i as Number)).abs() < Number::EPSILON => Value::Integer(i),
+                    Some(i) if n.to_bits() == (i as Number).to_bits() => Value::Integer(i),
                     _ => Value::Number(n),
                 }
             }
@@ -816,21 +895,14 @@ impl RawLua {
     #[inline]
     pub(crate) unsafe fn pop_ref(&self) -> ValueRef {
         ffi::lua_xmove(self.state(), self.ref_thread(), 1);
-        let index = ref_stack_pop(self.extra.get());
+        let index = (*self.extra.get()).ref_stack_pop();
         ValueRef::new(self, index)
     }
 
     // Same as `pop_ref` but assumes the value is already on the reference thread
     #[inline]
     pub(crate) unsafe fn pop_ref_thread(&self) -> ValueRef {
-        let index = ref_stack_pop(self.extra.get());
-        ValueRef::new(self, index)
-    }
-
-    #[inline]
-    pub(crate) unsafe fn clone_ref(&self, vref: &ValueRef) -> ValueRef {
-        ffi::lua_pushvalue(self.ref_thread(), vref.index);
-        let index = ref_stack_pop(self.extra.get());
+        let index = (*self.extra.get()).ref_stack_pop();
         ValueRef::new(self, index)
     }
 
@@ -851,7 +923,7 @@ impl RawLua {
         #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
         ffi::lua_xpush(self.ref_thread(), state, ExtraData::ERROR_TRACEBACK_IDX);
         // Lua 5.2+ support light C functions that does not require extra allocations
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
         ffi::lua_pushcfunction(state, crate::util::error_traceback);
     }
 
@@ -920,7 +992,7 @@ impl RawLua {
         // We generate metatable first to make sure it *always* available when userdata pushed
         let mt_id = get_metatable_id()?;
         let protect = !self.unlikely_memory_error();
-        crate::util::push_userdata(state, data, protect)?;
+        push_userdata(state, data, protect)?;
         ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, mt_id);
         ffi::lua_setmetatable(state, -2);
 
@@ -1048,6 +1120,18 @@ impl RawLua {
             field_setters_index = Some(ffi::lua_absindex(state, -1));
         }
 
+        // Create methods namecall table
+        #[cfg_attr(not(feature = "luau"), allow(unused_mut))]
+        let mut methods_map = None;
+        #[cfg(feature = "luau")]
+        if registry.enable_namecall {
+            let map: &mut rustc_hash::FxHashMap<_, crate::types::CallbackPtr> =
+                methods_map.get_or_insert_with(Default::default);
+            for (k, m) in &registry.methods {
+                map.insert(k.as_bytes().to_vec(), &**m);
+            }
+        }
+
         let mut methods_index = None;
         let methods_nrec = registry.methods.len();
         #[cfg(feature = "async")]
@@ -1095,6 +1179,7 @@ impl RawLua {
             field_getters_index,
             field_setters_index,
             methods_index,
+            methods_map,
         )?;
 
         // Update stack guard to keep metatable after return
@@ -1134,7 +1219,10 @@ impl RawLua {
             Ok(type_id) => Ok(type_id),
             Err(Error::UserDataTypeMismatch) if ffi::lua_type(state, idx) != ffi::LUA_TUSERDATA => {
                 // Report `FromLuaConversionError` instead
-                let idx_type_name = CStr::from_ptr(ffi::luaL_typename(state, idx));
+                // In Luau `luaL_typename` return heap-allocated string that is valid only for
+                // the `state` lifetime.
+                // `lua_typename` is used instead to get a truly static string.
+                let idx_type_name = CStr::from_ptr(ffi::lua_typename(state, ffi::lua_type(state, idx)));
                 let idx_type_name = idx_type_name.to_str().unwrap();
                 let message = format!("expected userdata of type '{}'", short_type_name::<T>());
                 Err(Error::from_lua_conversion(idx_type_name, "userdata", message))
@@ -1218,7 +1306,13 @@ impl RawLua {
     #[cfg(feature = "async")]
     pub(crate) fn create_async_callback(&self, func: AsyncCallback) -> Result<Function> {
         // Ensure that the coroutine library is loaded
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau"))]
+        #[cfg(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "luau"
+        ))]
         unsafe {
             if !(*self.extra.get()).libs.contains(StdLib::COROUTINE) {
                 load_std_libs(self.main_state(), StdLib::COROUTINE)?;
@@ -1226,7 +1320,7 @@ impl RawLua {
             }
         }
 
-        unsafe extern "C-unwind" fn call_callback(state: *mut ffi::lua_State) -> c_int {
+        unsafe extern "C-unwind" fn get_future_callback(state: *mut ffi::lua_State) -> c_int {
             // Async functions cannot be scoped and therefore destroyed,
             // so the first upvalue is always valid
             let upvalue = get_userdata::<AsyncCallbackUpvalue>(state, ffi::lua_upvalueindex(1));
@@ -1240,36 +1334,37 @@ impl RawLua {
                 let extra = XRc::clone(&(*upvalue).extra);
                 let protect = !rawlua.unlikely_memory_error();
                 push_internal_userdata(state, AsyncPollUpvalue { data: fut, extra }, protect)?;
-                if protect {
-                    protect_lua!(state, 1, 1, fn(state) {
-                        ffi::lua_pushcclosure(state, poll_future, 1);
-                    })?;
-                } else {
-                    ffi::lua_pushcclosure(state, poll_future, 1);
-                }
 
                 Ok(1)
             })
         }
 
         unsafe extern "C-unwind" fn poll_future(state: *mut ffi::lua_State) -> c_int {
-            let upvalue = get_userdata::<AsyncPollUpvalue>(state, ffi::lua_upvalueindex(1));
-            callback_error_ext(state, (*upvalue).extra.get(), true, |extra, nargs| {
+            // Future is always passed in the first argument
+            let future = get_userdata::<AsyncPollUpvalue>(state, 1);
+            callback_error_ext(state, (*future).extra.get(), true, |extra, nargs| {
                 // Lua ensures that `LUA_MINSTACK` stack spaces are available (after pushing arguments)
                 // The lock must be already held as the future is polled
                 let rawlua = (*extra).raw_lua();
 
-                if nargs == 1 && ffi::lua_tolightuserdata(state, -1) == Lua::poll_terminate().0 {
+                if nargs == 2 && ffi::lua_tolightuserdata(state, -1) == Lua::poll_terminate().0 {
                     // Destroy the future and terminate the Lua thread
-                    (*upvalue).data.take();
-                    ffi::lua_pushinteger(state, 0);
+                    (*future).data.take();
+                    ffi::lua_pushinteger(state, -1);
                     return Ok(1);
                 }
 
-                let fut = &mut (*upvalue).data;
+                let fut = &mut (*future).data;
                 let mut ctx = Context::from_waker(rawlua.waker());
                 match fut.as_mut().map(|fut| fut.as_mut().poll(&mut ctx)) {
                     Some(Poll::Pending) => {
+                        let fut_nvals = ffi::lua_gettop(state) - 1; // Exclude the future itself
+                        if fut_nvals >= 3 && ffi::lua_tolightuserdata(state, -3) == Lua::poll_yield().0 {
+                            // We have some values to yield
+                            ffi::lua_pushnil(state);
+                            ffi::lua_replace(state, -4);
+                            return Ok(3);
+                        }
                         ffi::lua_pushnil(state);
                         ffi::lua_pushlightuserdata(state, Lua::poll_pending().0);
                         Ok(2)
@@ -1298,7 +1393,7 @@ impl RawLua {
         }
 
         let state = self.state();
-        let get_poll = unsafe {
+        let get_future = unsafe {
             let _sg = StackGuard::new(state);
             check_stack(state, 4)?;
 
@@ -1308,10 +1403,10 @@ impl RawLua {
             push_internal_userdata(state, upvalue, protect)?;
             if protect {
                 protect_lua!(state, 1, 1, fn(state) {
-                    ffi::lua_pushcclosure(state, call_callback, 1);
+                    ffi::lua_pushcclosure(state, get_future_callback, 1);
                 })?;
             } else {
-                ffi::lua_pushcclosure(state, call_callback, 1);
+                ffi::lua_pushcclosure(state, get_future_callback, 1);
             }
 
             Function(self.pop_ref())
@@ -1330,16 +1425,19 @@ impl RawLua {
         let coroutine = lua.globals().get::<Table>("coroutine")?;
 
         // Prepare environment for the async poller
-        let env = lua.create_table_with_capacity(0, 3)?;
-        env.set("get_poll", get_poll)?;
+        let env = lua.create_table_with_capacity(0, 4)?;
+        env.set("get_future", get_future)?;
+        env.set("poll", unsafe { lua.create_c_function(poll_future)? })?;
         env.set("yield", coroutine.get::<Function>("yield")?)?;
         env.set("unpack", unsafe { lua.create_c_function(unpack)? })?;
 
         lua.load(
             r#"
-            local poll = get_poll(...)
-            local nres, res, res2 = poll()
+            local poll, yield = poll, yield
+            local future = get_future(...)
+            local nres, res, res2 = poll(future)
             while true do
+                -- Poll::Ready branch, `nres` is the number of results
                 if nres ~= nil then
                     if nres == 0 then
                         return
@@ -1347,14 +1445,28 @@ impl RawLua {
                         return res
                     elseif nres == 2 then
                         return res, res2
+                    elseif nres < 0 then
+                        -- Negative `nres` means that the future is terminated
+                        -- It must stay yielded and never be resumed again
+                        yield()
                     else
                         return unpack(res, nres)
                     end
                 end
-                -- `res` is a "pending" value
-                -- `yield` can return a signal to drop the future that we should propagate
-                -- to the poller
-                nres, res, res2 = poll(yield(res))
+
+                -- Poll::Pending branch
+                if res2 == nil then
+                    -- `res` is a "pending" value
+                    -- `yield` can return a signal to drop the future that we should propagate
+                    -- to the poller
+                    nres, res, res2 = poll(future, yield(res))
+                elseif res2 == 0 then
+                    nres, res, res2 = poll(future, yield())
+                elseif res2 == 1 then
+                    nres, res, res2 = poll(future, yield(res))
+                else
+                    nres, res, res2 = poll(future, yield(unpack(res, res2)))
+                end
             end
             "#,
         )
@@ -1366,14 +1478,14 @@ impl RawLua {
 
     #[cfg(feature = "async")]
     #[inline]
-    pub(crate) unsafe fn waker(&self) -> &Waker {
-        (*self.extra.get()).waker.as_ref()
+    pub(crate) fn waker(&self) -> &Waker {
+        unsafe { (*self.extra.get()).waker.as_ref() }
     }
 
     #[cfg(feature = "async")]
     #[inline]
-    pub(crate) unsafe fn set_waker(&self, waker: NonNull<Waker>) -> NonNull<Waker> {
-        mem::replace(&mut (*self.extra.get()).waker, waker)
+    pub(crate) fn set_waker(&self, waker: NonNull<Waker>) -> NonNull<Waker> {
+        unsafe { mem::replace(&mut (*self.extra.get()).waker, waker) }
     }
 }
 
@@ -1413,7 +1525,13 @@ unsafe fn load_std_libs(state: *mut ffi::lua_State, libs: StdLib) -> Result<()>
     #[cfg(feature = "luajit")]
     let _gc_guard = GcGuard::new(state);
 
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau"))]
+    #[cfg(any(
+        feature = "lua55",
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luau"
+    ))]
     {
         if libs.contains(StdLib::COROUTINE) {
             requiref(state, ffi::LUA_COLIBNAME, ffi::luaopen_coroutine, 1)?;
@@ -1437,7 +1555,7 @@ unsafe fn load_std_libs(state: *mut ffi::lua_State, libs: StdLib) -> Result<()>
         requiref(state, ffi::LUA_STRLIBNAME, ffi::luaopen_string, 1)?;
     }
 
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau"))]
     {
         if libs.contains(StdLib::UTF8) {
             requiref(state, ffi::LUA_UTF8LIBNAME, ffi::luaopen_utf8, 1)?;

src/state/util.rs

@@ -89,7 +89,7 @@ where
                 PreallocatedFailure::New(_) => {
                     ffi::lua_rotate(state, 1, -1);
                     ffi::lua_xmove(state, ref_thread, 1);
-                    let index = ref_stack_pop(extra);
+                    let index = (*extra).ref_stack_pop();
                     (*extra).wrapped_failure_pool.push(index);
                     (*extra).wrapped_failure_top += 1;
                 }
@@ -150,31 +150,3 @@ where
         }
     }
 }
-
-pub(super) unsafe fn ref_stack_pop(extra: *mut ExtraData) -> c_int {
-    let extra = &mut *extra;
-    if let Some(free) = extra.ref_free.pop() {
-        ffi::lua_replace(extra.ref_thread, free);
-        return free;
-    }
-
-    // Try to grow max stack size
-    if extra.ref_stack_top >= extra.ref_stack_size {
-        let mut inc = extra.ref_stack_size; // Try to double stack size
-        while inc > 0 && ffi::lua_checkstack(extra.ref_thread, inc) == 0 {
-            inc /= 2;
-        }
-        if inc == 0 {
-            // Pop item on top of the stack to avoid stack leaking and successfully run destructors
-            // during unwinding.
-            ffi::lua_pop(extra.ref_thread, 1);
-            let top = extra.ref_stack_top;
-            // It is a user error to create enough references to exhaust the Lua max stack size for
-            // the ref thread.
-            panic!("cannot create a Lua reference, out of auxiliary stack space (used {top} slots)");
-        }
-        extra.ref_stack_size += inc;
-    }
-    extra.ref_stack_top += 1;
-    extra.ref_stack_top
-}

src/stdlib.rs

@@ -6,10 +6,22 @@ pub struct StdLib(u32);
 
 impl StdLib {
     /// [`coroutine`](https://www.lua.org/manual/5.4/manual.html#6.2) library
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau"))]
+    #[cfg(any(
+        feature = "lua55",
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luau"
+    ))]
     #[cfg_attr(
         docsrs,
-        doc(cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luau")))
+        doc(cfg(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "luau"
+        )))
     )]
     pub const COROUTINE: StdLib = StdLib(1);
 
@@ -28,8 +40,11 @@ impl StdLib {
     pub const STRING: StdLib = StdLib(1 << 4);
 
     /// [`utf8`](https://www.lua.org/manual/5.4/manual.html#6.5) library
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau")))
+    )]
     pub const UTF8: StdLib = StdLib(1 << 5);
 
     /// [`bit`](https://www.lua.org/manual/5.2/manual.html#6.7) library

src/string.rs

@@ -43,7 +43,7 @@ impl String {
     /// # }
     /// ```
     #[inline]
-    pub fn to_str(&self) -> Result<BorrowedStr> {
+    pub fn to_str(&self) -> Result<BorrowedStr<'_>> {
         BorrowedStr::try_from(self)
     }
 
@@ -86,7 +86,7 @@ impl String {
 
     /// Get the bytes that make up this string.
     ///
-    /// The returned slice will not contain the terminating nul byte, but will contain any nul
+    /// The returned slice will not contain the terminating null byte, but will contain any null
     /// bytes embedded into the Lua string.
     ///
     /// # Examples
@@ -102,19 +102,19 @@ impl String {
     /// # }
     /// ```
     #[inline]
-    pub fn as_bytes(&self) -> BorrowedBytes {
+    pub fn as_bytes(&self) -> BorrowedBytes<'_> {
         BorrowedBytes::from(self)
     }
 
-    /// Get the bytes that make up this string, including the trailing nul byte.
-    pub fn as_bytes_with_nul(&self) -> BorrowedBytes {
+    /// Get the bytes that make up this string, including the trailing null byte.
+    pub fn as_bytes_with_nul(&self) -> BorrowedBytes<'_> {
         let BorrowedBytes { buf, borrow, _lua } = BorrowedBytes::from(self);
-        // Include the trailing nul byte (it's always present but excluded by default)
+        // Include the trailing null byte (it's always present but excluded by default)
         let buf = unsafe { slice::from_raw_parts((*buf).as_ptr(), (*buf).len() + 1) };
         BorrowedBytes { buf, borrow, _lua }
     }
 
-    // Does not return the terminating nul byte
+    // Does not return the terminating null byte
     unsafe fn to_slice(&self) -> (&[u8], Lua) {
         let lua = self.0.lua.upgrade();
         let slice = {

src/table.rs

@@ -1,19 +1,19 @@
 use std::collections::HashSet;
 use std::fmt;
 use std::marker::PhantomData;
-use std::os::raw::{c_int, c_void};
+use std::os::raw::c_void;
 use std::string::String as StdString;
 
 use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::state::{LuaGuard, RawLua};
+use crate::state::{LuaGuard, RawLua, WeakLua};
 use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti, ObjectLike};
-use crate::types::{Integer, LuaType, ValueRef};
+use crate::types::{Integer, ValueRef};
 use crate::util::{assert_stack, check_stack, get_metatable_ptr, StackGuard};
 use crate::value::{Nil, Value};
 
 #[cfg(feature = "async")]
-use futures_util::future::{self, Either, Future};
+use crate::function::AsyncCallFuture;
 
 #[cfg(feature = "serde")]
 use {
@@ -211,7 +211,7 @@ impl Table {
     ///
     /// let always_equals_mt = lua.create_table()?;
     /// always_equals_mt.set("__eq", lua.create_function(|_, (_t1, _t2): (Table, Table)| Ok(true))?)?;
-    /// table2.set_metatable(Some(always_equals_mt));
+    /// table2.set_metatable(Some(always_equals_mt))?;
     ///
     /// assert!(table1.equals(&table1.clone())?);
     /// assert!(table1.equals(&table2)?);
@@ -416,14 +416,7 @@ impl Table {
 
                 lua.push_ref(&self.0);
 
-                // Clear array part
-                for i in 1..=ffi::lua_rawlen(state, -1) {
-                    ffi::lua_pushnil(state);
-                    ffi::lua_rawseti(state, -2, i as Integer);
-                }
-
-                // Clear hash part
-                // It must be safe as long as we don't use invalid keys
+                // This is safe as long as we don't assign new keys
                 ffi::lua_pushnil(state);
                 while ffi::lua_next(state, -2) != 0 {
                     ffi::lua_pop(state, 1); // pop value
@@ -487,16 +480,12 @@ impl Table {
     /// [`getmetatable`]: https://www.lua.org/manual/5.4/manual.html#pdf-getmetatable
     pub fn metatable(&self) -> Option<Table> {
         let lua = self.0.lua.lock();
-        let state = lua.state();
+        let ref_thread = lua.ref_thread();
         unsafe {
-            let _sg = StackGuard::new(state);
-            assert_stack(state, 2);
-
-            lua.push_ref(&self.0);
-            if ffi::lua_getmetatable(state, -1) == 0 {
+            if ffi::lua_getmetatable(ref_thread, self.0.index) == 0 {
                 None
             } else {
-                Some(Table(lua.pop_ref()))
+                Some(Table(lua.pop_ref_thread()))
             }
         }
     }
@@ -505,27 +494,23 @@ impl Table {
     ///
     /// If `metatable` is `None`, the metatable is removed (if no metatable is set, this does
     /// nothing).
-    pub fn set_metatable(&self, metatable: Option<Table>) {
-        // Workaround to throw readonly error without returning Result
+    pub fn set_metatable(&self, metatable: Option<Table>) -> Result<()> {
         #[cfg(feature = "luau")]
         if self.is_readonly() {
-            panic!("attempt to modify a readonly table");
+            return Err(Error::runtime("attempt to modify a readonly table"));
         }
 
         let lua = self.0.lua.lock();
-        let state = lua.state();
+        let ref_thread = lua.ref_thread();
         unsafe {
-            let _sg = StackGuard::new(state);
-            assert_stack(state, 2);
-
-            lua.push_ref(&self.0);
-            if let Some(metatable) = metatable {
-                lua.push_ref(&metatable.0);
+            if let Some(metatable) = &metatable {
+                ffi::lua_pushvalue(ref_thread, metatable.0.index);
             } else {
-                ffi::lua_pushnil(state);
+                ffi::lua_pushnil(ref_thread);
             }
-            ffi::lua_setmetatable(state, -2);
+            ffi::lua_setmetatable(ref_thread, self.0.index);
         }
+        Ok(())
     }
 
     /// Returns true if the table has metatable attached.
@@ -613,7 +598,7 @@ impl Table {
     /// ```
     ///
     /// [Lua manual]: http://www.lua.org/manual/5.4/manual.html#pdf-next
-    pub fn pairs<K: FromLua, V: FromLua>(&self) -> TablePairs<K, V> {
+    pub fn pairs<K: FromLua, V: FromLua>(&self) -> TablePairs<'_, K, V> {
         TablePairs {
             guard: self.0.lua.lock(),
             table: self,
@@ -678,21 +663,30 @@ impl Table {
     /// # Ok(())
     /// # }
     /// ```
-    pub fn sequence_values<V: FromLua>(&self) -> TableSequence<V> {
+    pub fn sequence_values<V: FromLua>(&self) -> TableSequence<'_, V> {
         TableSequence {
             guard: self.0.lua.lock(),
             table: self,
             index: 1,
+            len: None,
             _phantom: PhantomData,
         }
     }
 
     /// Iterates over the sequence part of the table, invoking the given closure on each value.
+    ///
+    /// This methods is similar to [`Table::sequence_values`], but optimized for performance.
     #[doc(hidden)]
-    pub fn for_each_value<V>(&self, mut f: impl FnMut(V) -> Result<()>) -> Result<()>
-    where
-        V: FromLua,
-    {
+    pub fn for_each_value<V: FromLua>(&self, f: impl FnMut(V) -> Result<()>) -> Result<()> {
+        self.for_each_value_by_len(None, f)
+    }
+
+    fn for_each_value_by_len<V: FromLua>(
+        &self,
+        len: impl Into<Option<usize>>,
+        mut f: impl FnMut(V) -> Result<()>,
+    ) -> Result<()> {
+        let len = len.into();
         let lua = self.0.lua.lock();
         let state = lua.state();
         unsafe {
@@ -700,9 +694,14 @@ impl Table {
             check_stack(state, 4)?;
 
             lua.push_ref(&self.0);
-            let len = ffi::lua_rawlen(state, -1);
-            for i in 1..=len {
-                ffi::lua_rawgeti(state, -1, i as _);
+            for i in 1.. {
+                if len.map(|len| i > len).unwrap_or(false) {
+                    break;
+                }
+                let t = ffi::lua_rawgeti(state, -1, i as _);
+                if len.is_none() && t == ffi::LUA_TNIL {
+                    break;
+                }
                 f(V::from_stack(-1, &lua)?)?;
                 ffi::lua_pop(state, 1);
             }
@@ -735,8 +734,9 @@ impl Table {
         Ok(())
     }
 
+    /// Checks if the table has the array metatable attached.
     #[cfg(feature = "serde")]
-    pub(crate) fn is_array(&self) -> bool {
+    fn has_array_metatable(&self) -> bool {
         let lua = self.0.lua.lock();
         let state = lua.state();
         unsafe {
@@ -752,6 +752,70 @@ impl Table {
         }
     }
 
+    /// If the table is an array, returns the number of non-nil elements and max index.
+    ///
+    /// Returns `None` if the table is not an array.
+    ///
+    /// This operation has O(n) complexity.
+    #[cfg(feature = "serde")]
+    fn find_array_len(&self) -> Option<(usize, usize)> {
+        let lua = self.0.lua.lock();
+        let ref_thread = lua.ref_thread();
+        unsafe {
+            let _sg = StackGuard::new(ref_thread);
+
+            let (mut count, mut max_index) = (0, 0);
+            ffi::lua_pushnil(ref_thread);
+            while ffi::lua_next(ref_thread, self.0.index) != 0 {
+                if ffi::lua_type(ref_thread, -2) != ffi::LUA_TNUMBER {
+                    return None;
+                }
+
+                let k = ffi::lua_tonumber(ref_thread, -2);
+                if k.trunc() != k || k < 1.0 {
+                    return None;
+                }
+                max_index = std::cmp::max(max_index, k as usize);
+                count += 1;
+                ffi::lua_pop(ref_thread, 1);
+            }
+            Some((count, max_index))
+        }
+    }
+
+    /// Determines if the table should be encoded as an array or a map.
+    ///
+    /// The algorithm is the following:
+    /// 1. If `detect_mixed_tables` is enabled, iterate over all keys in the table checking is they
+    ///    all are positive integers. If non-array key is found, return `None` (encode as map).
+    ///    Otherwise check the sparsity of the array. Too sparse arrays are encoded as maps.
+    ///
+    /// 2. If `detect_mixed_tables` is disabled, check if the table has a positive length or has the
+    ///    array metatable. If so, encode as array. If the table is empty and
+    ///    `encode_empty_tables_as_array` is enabled, encode as array.
+    ///
+    /// Returns the length of the array if it should be encoded as an array.
+    #[cfg(feature = "serde")]
+    pub(crate) fn encode_as_array(&self, options: crate::serde::de::Options) -> Option<usize> {
+        if options.detect_mixed_tables {
+            if let Some((len, max_idx)) = self.find_array_len() {
+                // If the array is too sparse, serialize it as a map instead
+                if len < 10 || len * 2 >= max_idx {
+                    return Some(max_idx);
+                }
+            }
+        } else {
+            let len = self.raw_len();
+            if len > 0 || self.has_array_metatable() {
+                return Some(len);
+            }
+            if options.encode_empty_tables_as_array && self.is_empty() {
+                return Some(0);
+            }
+        }
+        None
+    }
+
     #[cfg(feature = "luau")]
     #[inline(always)]
     fn check_readonly_write(&self, lua: &RawLua) -> Result<()> {
@@ -871,10 +935,6 @@ where
     }
 }
 
-impl LuaType for Table {
-    const TYPE_ID: c_int = ffi::LUA_TTABLE;
-}
-
 impl ObjectLike for Table {
     #[inline]
     fn get<V: FromLua>(&self, key: impl IntoLua) -> Result<V> {
@@ -892,16 +952,16 @@ impl ObjectLike for Table {
         R: FromLuaMulti,
     {
         // Convert table to a function and call via pcall that respects the `__call` metamethod.
-        Function(self.0.copy()).call(args)
+        Function(self.0.clone()).call(args)
     }
 
     #[cfg(feature = "async")]
     #[inline]
-    fn call_async<R>(&self, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async<R>(&self, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti,
     {
-        Function(self.0.copy()).call_async(args)
+        Function(self.0.clone()).call_async(args)
     }
 
     #[inline]
@@ -913,7 +973,7 @@ impl ObjectLike for Table {
     }
 
     #[cfg(feature = "async")]
-    fn call_async_method<R>(&self, name: &str, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async_method<R>(&self, name: &str, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti,
     {
@@ -933,23 +993,33 @@ impl ObjectLike for Table {
 
     #[cfg(feature = "async")]
     #[inline]
-    fn call_async_function<R>(&self, name: &str, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async_function<R>(&self, name: &str, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti,
     {
         match self.get(name) {
-            Ok(Value::Function(func)) => Either::Left(func.call_async(args)),
+            Ok(Value::Function(func)) => func.call_async(args),
             Ok(val) => {
                 let msg = format!("attempt to call a {} value (function '{name}')", val.type_name());
-                Either::Right(future::ready(Err(Error::RuntimeError(msg))))
+                AsyncCallFuture::error(Error::RuntimeError(msg))
             }
-            Err(err) => Either::Right(future::ready(Err(err))),
+            Err(err) => AsyncCallFuture::error(err),
         }
     }
 
     #[inline]
     fn to_string(&self) -> Result<StdString> {
-        Value::Table(Table(self.0.copy())).to_string()
+        Value::Table(Table(self.0.clone())).to_string()
+    }
+
+    #[inline]
+    fn to_value(&self) -> Value {
+        Value::Table(self.clone())
+    }
+
+    #[inline]
+    fn weak_lua(&self) -> &WeakLua {
+        &self.0.lua
     }
 }
 
@@ -985,6 +1055,15 @@ impl<'a> SerializableTable<'a> {
     }
 }
 
+impl<V> TableSequence<'_, V> {
+    /// Sets the length (hint) of the sequence.
+    #[cfg(feature = "serde")]
+    pub(crate) fn with_len(mut self, len: usize) -> Self {
+        self.len = Some(len);
+        self
+    }
+}
+
 #[cfg(feature = "serde")]
 impl Serialize for SerializableTable<'_> {
     fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
@@ -1006,14 +1085,10 @@ impl Serialize for SerializableTable<'_> {
         let _guard = RecursionGuard::new(self.table, visited);
 
         // Array
-        let len = self.table.raw_len();
-        if len > 0
-            || self.table.is_array()
-            || (self.options.encode_empty_tables_as_array && self.table.is_empty())
-        {
+        if let Some(len) = self.table.encode_as_array(self.options) {
             let mut seq = serializer.serialize_seq(Some(len))?;
             let mut serialize_err = None;
-            let res = self.table.for_each_value::<Value>(|value| {
+            let res = self.table.for_each_value_by_len::<Value>(len, |value| {
                 let skip = check_value_for_skip(&value, self.options, visited)
                     .map_err(|err| Error::SerializeError(err.to_string()))?;
                 if skip {
@@ -1137,13 +1212,11 @@ pub struct TableSequence<'a, V> {
     guard: LuaGuard,
     table: &'a Table,
     index: Integer,
+    len: Option<usize>,
     _phantom: PhantomData<V>,
 }
 
-impl<V> Iterator for TableSequence<'_, V>
-where
-    V: FromLua,
-{
+impl<V: FromLua> Iterator for TableSequence<'_, V> {
     type Item = Result<V>;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -1157,7 +1230,7 @@ where
 
             lua.push_ref(&self.table.0);
             match ffi::lua_rawgeti(state, -1, self.index) {
-                ffi::LUA_TNIL => None,
+                ffi::LUA_TNIL if self.index as usize > self.len.unwrap_or(0) => None,
                 _ => {
                     self.index += 1;
                     Some(V::from_stack(-1, lua))

src/thread.rs

@@ -10,7 +10,7 @@ use crate::util::{check_stack, error_traceback_thread, pop_error, StackGuard};
 
 #[cfg(not(feature = "luau"))]
 use crate::{
-    hook::{Debug, HookTriggers},
+    debug::{Debug, HookTriggers},
     types::HookKind,
 };
 
@@ -86,13 +86,15 @@ unsafe impl Sync for Thread {}
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct AsyncThread<R> {
     thread: Thread,
-    ret: PhantomData<R>,
+    ret: PhantomData<fn() -> R>,
     recycle: bool,
 }
 
 impl Thread {
+    /// Returns reference to the Lua state that this thread is associated with.
+    #[doc(hidden)]
     #[inline(always)]
-    fn state(&self) -> *mut ffi::lua_State {
+    pub fn state(&self) -> *mut ffi::lua_State {
         self.1
     }
 
@@ -154,7 +156,6 @@ impl Thread {
         let thread_state = self.state();
         unsafe {
             let _sg = StackGuard::new(state);
-            let _thread_sg = StackGuard::with_top(thread_state, 0);
 
             let nargs = args.push_into_stack_multi(&lua)?;
             if nargs > 0 {
@@ -163,6 +164,7 @@ impl Thread {
                 pushed_nargs += nargs;
             }
 
+            let _thread_sg = StackGuard::with_top(thread_state, 0);
             let (_, nresults) = self.resume_inner(&lua, pushed_nargs)?;
             check_stack(state, nresults + 1)?;
             ffi::lua_xmove(thread_state, state, nresults);
@@ -190,12 +192,12 @@ impl Thread {
         let thread_state = self.state();
         unsafe {
             let _sg = StackGuard::new(state);
-            let _thread_sg = StackGuard::with_top(thread_state, 0);
 
             check_stack(state, 1)?;
             error.push_into_stack(&lua)?;
             ffi::lua_xmove(state, thread_state, 1);
 
+            let _thread_sg = StackGuard::with_top(thread_state, 0);
             let (_, nresults) = self.resume_inner(&lua, ffi::LUA_RESUMEERROR)?;
             check_stack(state, nresults + 1)?;
             ffi::lua_xmove(thread_state, state, nresults);
@@ -269,7 +271,7 @@ impl Thread {
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn set_hook<F>(&self, triggers: HookTriggers, callback: F) -> Result<()>
     where
-        F: Fn(&crate::Lua, Debug) -> Result<crate::VmState> + crate::MaybeSend + 'static,
+        F: Fn(&crate::Lua, &Debug) -> Result<crate::VmState> + crate::MaybeSend + 'static,
     {
         let lua = self.0.lua.lock();
         unsafe {
@@ -334,22 +336,22 @@ impl Thread {
             }
             ThreadStatusInner::Running => Err(Error::runtime("cannot reset a running thread")),
             ThreadStatusInner::Finished => Ok(()),
-            #[cfg(not(any(feature = "lua54", feature = "luau")))]
+            #[cfg(not(any(feature = "lua55", feature = "lua54", feature = "luau")))]
             ThreadStatusInner::Yielded(_) | ThreadStatusInner::Error => {
                 Err(Error::runtime("cannot reset non-finished thread"))
             }
-            #[cfg(any(feature = "lua54", feature = "luau"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "luau"))]
             ThreadStatusInner::Yielded(_) | ThreadStatusInner::Error => {
                 let thread_state = self.state();
 
                 #[cfg(all(feature = "lua54", not(feature = "vendored")))]
                 let status = ffi::lua_resetthread(thread_state);
-                #[cfg(all(feature = "lua54", feature = "vendored"))]
+                #[cfg(any(feature = "lua55", all(feature = "lua54", feature = "vendored")))]
                 let status = {
                     let lua = self.0.lua.lock();
                     ffi::lua_closethread(thread_state, lua.state())
                 };
-                #[cfg(feature = "lua54")]
+                #[cfg(any(feature = "lua55", feature = "lua54"))]
                 if status != ffi::LUA_OK {
                     return Err(pop_error(thread_state, status));
                 }
@@ -529,6 +531,7 @@ impl<R> Drop for AsyncThread<R> {
                         // The thread is dropped while yielded, resume it with the "terminate" signal
                         ffi::lua_pushlightuserdata(self.thread.1, crate::Lua::poll_terminate().0);
                         if let Ok((new_status, _)) = self.thread.resume_inner(&lua, 1) {
+                            // `new_status` should always be `ThreadStatusInner::Yielded(0)`
                             status = new_status;
                         }
                     }
@@ -601,7 +604,7 @@ impl<R: FromLuaMulti> Future for AsyncThread<R> {
 
             if status.is_yielded() {
                 if !(nresults == 1 && is_poll_pending(thread_state)) {
-                    // Ignore value returned via yield()
+                    // Ignore values returned via yield()
                     cx.waker().wake_by_ref();
                 }
                 return Poll::Pending;
@@ -632,7 +635,7 @@ struct WakerGuard<'lua, 'a> {
 impl<'lua, 'a> WakerGuard<'lua, 'a> {
     #[inline]
     pub fn new(lua: &'lua RawLua, waker: &'a Waker) -> Result<WakerGuard<'lua, 'a>> {
-        let prev = unsafe { lua.set_waker(NonNull::from(waker)) };
+        let prev = lua.set_waker(NonNull::from(waker));
         Ok(WakerGuard {
             lua,
             prev,
@@ -644,7 +647,7 @@ impl<'lua, 'a> WakerGuard<'lua, 'a> {
 #[cfg(feature = "async")]
 impl Drop for WakerGuard<'_, '_> {
     fn drop(&mut self) {
-        unsafe { self.lua.set_waker(self.prev) };
+        self.lua.set_waker(self.prev);
     }
 }
 

src/traits.rs

@@ -5,13 +5,13 @@ use std::sync::Arc;
 use crate::error::{Error, Result};
 use crate::multi::MultiValue;
 use crate::private::Sealed;
-use crate::state::{Lua, RawLua};
+use crate::state::{Lua, RawLua, WeakLua};
 use crate::types::MaybeSend;
-use crate::util::{check_stack, short_type_name};
+use crate::util::{check_stack, parse_lookup_path, short_type_name};
 use crate::value::Value;
 
 #[cfg(feature = "async")]
-use std::future::Future;
+use {crate::function::AsyncCallFuture, std::future::Future};
 
 /// Trait for types convertible to [`Value`].
 pub trait IntoLua: Sized {
@@ -162,7 +162,7 @@ pub trait ObjectLike: Sealed {
     /// arguments.
     #[cfg(feature = "async")]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn call_async<R>(&self, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async<R>(&self, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti;
 
@@ -178,7 +178,7 @@ pub trait ObjectLike: Sealed {
     /// This might invoke the `__index` metamethod.
     #[cfg(feature = "async")]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn call_async_method<R>(&self, name: &str, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async_method<R>(&self, name: &str, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti;
 
@@ -196,14 +196,54 @@ pub trait ObjectLike: Sealed {
     /// This might invoke the `__index` metamethod.
     #[cfg(feature = "async")]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn call_async_function<R>(&self, name: &str, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async_function<R>(&self, name: &str, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti;
 
+    /// Look up a value by a path of keys.
+    ///
+    /// The syntax is similar to accessing nested tables in Lua, with additional support for
+    /// `?` operator to perform safe navigation.
+    ///
+    /// For example, the path `a[1].c` is equivalent to `table.a[1].c` in Lua.
+    /// With `?` operator, `a[1]?.c` is equivalent to `table.a[1] and table.a[1].c or nil` in Lua.
+    ///
+    /// Bracket notation rules:
+    /// - `[123]` - integer keys
+    /// - `["string key"]` or `['string key']` - string keys (must be quoted)
+    /// - String keys support escape sequences: `\"`, `\'`, `\\`
+    fn get_path<V: FromLua>(&self, path: &str) -> Result<V> {
+        let mut current = self.to_value();
+        for (key, safe_nil) in parse_lookup_path(path)? {
+            current = match current {
+                Value::Table(table) => table.get::<Value>(key),
+                Value::UserData(ud) => ud.get::<Value>(key),
+                _ => {
+                    let type_name = current.type_name();
+                    let err = format!("attempt to index a {type_name} value with key '{key}'");
+                    Err(Error::runtime(err))
+                }
+            }?;
+            if safe_nil && (current == Value::Nil || current == Value::NULL) {
+                break;
+            }
+        }
+
+        let lua = self.weak_lua().lock();
+        V::from_lua(current, lua.lua())
+    }
+
     /// Converts the object to a string in a human-readable format.
     ///
     /// This might invoke the `__tostring` metamethod.
     fn to_string(&self) -> Result<StdString>;
+
+    /// Converts the object to a Lua value.
+    fn to_value(&self) -> Value;
+
+    /// Gets a reference to the associated Lua state.
+    #[doc(hidden)]
+    fn weak_lua(&self) -> &WeakLua;
 }
 
 /// A trait for types that can be used as Lua functions.

src/types.rs

@@ -1,9 +1,9 @@
 use std::cell::UnsafeCell;
 use std::os::raw::{c_int, c_void};
 
-use crate::error::Result;
 #[cfg(not(feature = "luau"))]
-use crate::hook::{Debug, HookTriggers};
+use crate::debug::{Debug, HookTriggers};
+use crate::error::Result;
 use crate::state::{ExtraData, Lua, RawLua};
 
 // Re-export mutex wrappers
@@ -20,6 +20,9 @@ pub use either::Either;
 pub use registry_key::RegistryKey;
 pub(crate) use value_ref::ValueRef;
 
+#[cfg(feature = "async")]
+pub(crate) use value_ref::ValueRefIndex;
+
 /// Type of Lua integer numbers.
 pub type Integer = ffi::lua_Integer;
 /// Type of Lua floating point numbers.
@@ -35,10 +38,13 @@ unsafe impl Send for LightUserData {}
 unsafe impl Sync for LightUserData {}
 
 #[cfg(feature = "send")]
-pub(crate) type Callback = Box<dyn Fn(&RawLua, c_int) -> Result<c_int> + Send + 'static>;
+type CallbackFn<'a> = dyn Fn(&RawLua, c_int) -> Result<c_int> + Send + 'a;
 
 #[cfg(not(feature = "send"))]
-pub(crate) type Callback = Box<dyn Fn(&RawLua, c_int) -> Result<c_int> + 'static>;
+type CallbackFn<'a> = dyn Fn(&RawLua, c_int) -> Result<c_int> + 'a;
+
+pub(crate) type Callback = Box<CallbackFn<'static>>;
+pub(crate) type CallbackPtr = *const CallbackFn<'static>;
 
 pub(crate) type ScopedCallback<'s> = Box<dyn Fn(&RawLua, c_int) -> Result<c_int> + 's>;
 
@@ -79,10 +85,10 @@ pub(crate) enum HookKind {
 }
 
 #[cfg(all(feature = "send", not(feature = "luau")))]
-pub(crate) type HookCallback = XRc<dyn Fn(&Lua, Debug) -> Result<VmState> + Send>;
+pub(crate) type HookCallback = XRc<dyn Fn(&Lua, &Debug) -> Result<VmState> + Send>;
 
 #[cfg(all(not(feature = "send"), not(feature = "luau")))]
-pub(crate) type HookCallback = XRc<dyn Fn(&Lua, Debug) -> Result<VmState>>;
+pub(crate) type HookCallback = XRc<dyn Fn(&Lua, &Debug) -> Result<VmState>>;
 
 #[cfg(all(feature = "send", feature = "luau"))]
 pub(crate) type InterruptCallback = XRc<dyn Fn(&Lua) -> Result<VmState> + Send>;
@@ -102,10 +108,12 @@ pub(crate) type ThreadCollectionCallback = XRc<dyn Fn(crate::LightUserData) + Se
 #[cfg(all(not(feature = "send"), feature = "luau"))]
 pub(crate) type ThreadCollectionCallback = XRc<dyn Fn(crate::LightUserData)>;
 
-#[cfg(all(feature = "send", feature = "lua54"))]
+#[cfg(feature = "send")]
+#[cfg(any(feature = "lua55", feature = "lua54"))]
 pub(crate) type WarnCallback = XRc<dyn Fn(&Lua, &str, bool) -> Result<()> + Send>;
 
-#[cfg(all(not(feature = "send"), feature = "lua54"))]
+#[cfg(not(feature = "send"))]
+#[cfg(any(feature = "lua55", feature = "lua54"))]
 pub(crate) type WarnCallback = XRc<dyn Fn(&Lua, &str, bool) -> Result<()>>;
 
 /// A trait that adds `Send` requirement if `send` feature is enabled.
@@ -114,6 +122,7 @@ pub trait MaybeSend: Send {}
 #[cfg(feature = "send")]
 impl<T: Send> MaybeSend for T {}
 
+/// A trait that adds `Send` requirement if `send` feature is enabled.
 #[cfg(not(feature = "send"))]
 pub trait MaybeSend {}
 #[cfg(not(feature = "send"))]

src/types/app_data.rs

@@ -43,7 +43,7 @@ impl AppData {
 
     #[inline]
     #[track_caller]
-    pub(crate) fn borrow<T: 'static>(&self, guard: Option<LuaGuard>) -> Option<AppDataRef<T>> {
+    pub(crate) fn borrow<T: 'static>(&self, guard: Option<LuaGuard>) -> Option<AppDataRef<'_, T>> {
         match self.try_borrow(guard) {
             Ok(data) => data,
             Err(err) => panic!("already mutably borrowed: {err:?}"),
@@ -53,7 +53,7 @@ impl AppData {
     pub(crate) fn try_borrow<T: 'static>(
         &self,
         guard: Option<LuaGuard>,
-    ) -> Result<Option<AppDataRef<T>>, BorrowError> {
+    ) -> Result<Option<AppDataRef<'_, T>>, BorrowError> {
         let data = unsafe { &*self.container.get() }
             .get(&TypeId::of::<T>())
             .map(|c| c.try_borrow())
@@ -74,7 +74,7 @@ impl AppData {
 
     #[inline]
     #[track_caller]
-    pub(crate) fn borrow_mut<T: 'static>(&self, guard: Option<LuaGuard>) -> Option<AppDataRefMut<T>> {
+    pub(crate) fn borrow_mut<T: 'static>(&self, guard: Option<LuaGuard>) -> Option<AppDataRefMut<'_, T>> {
         match self.try_borrow_mut(guard) {
             Ok(data) => data,
             Err(err) => panic!("already borrowed: {err:?}"),
@@ -84,7 +84,7 @@ impl AppData {
     pub(crate) fn try_borrow_mut<T: 'static>(
         &self,
         guard: Option<LuaGuard>,
-    ) -> Result<Option<AppDataRefMut<T>>, BorrowMutError> {
+    ) -> Result<Option<AppDataRefMut<'_, T>>, BorrowMutError> {
         let data = unsafe { &*self.container.get() }
             .get(&TypeId::of::<T>())
             .map(|c| c.try_borrow_mut())

src/types/sync.rs

@@ -31,7 +31,7 @@ mod inner {
         }
 
         #[inline(always)]
-        pub(crate) fn lock(&self) -> ReentrantMutexGuard<T> {
+        pub(crate) fn lock(&self) -> ReentrantMutexGuard<'_, T> {
             ReentrantMutexGuard(&self.0)
         }
 

src/types/value_ref.rs

@@ -1,22 +1,39 @@
 use std::fmt;
 use std::os::raw::{c_int, c_void};
 
+use super::XRc;
 use crate::state::{RawLua, WeakLua};
 
 /// A reference to a Lua (complex) value stored in the Lua auxiliary thread.
+#[derive(Clone)]
 pub struct ValueRef {
     pub(crate) lua: WeakLua,
+    // Keep index separate to avoid additional indirection when accessing it.
     pub(crate) index: c_int,
-    pub(crate) drop: bool,
+    // If `index_count` is `None`, the value does not need to be destroyed.
+    pub(crate) index_count: Option<ValueRefIndex>,
+}
+
+/// A reference to a Lua value index in the auxiliary thread.
+/// It's cheap to clone and can be used to track the number of references to a value.
+#[derive(Clone)]
+pub(crate) struct ValueRefIndex(pub(crate) XRc<c_int>);
+
+impl From<c_int> for ValueRefIndex {
+    #[inline]
+    fn from(index: c_int) -> Self {
+        ValueRefIndex(XRc::new(index))
+    }
 }
 
 impl ValueRef {
     #[inline]
-    pub(crate) fn new(lua: &RawLua, index: c_int) -> Self {
+    pub(crate) fn new(lua: &RawLua, index: impl Into<ValueRefIndex>) -> Self {
+        let index = index.into();
         ValueRef {
             lua: lua.weak().clone(),
-            index,
-            drop: true,
+            index: *index.0,
+            index_count: Some(index),
         }
     }
 
@@ -25,16 +42,6 @@ impl ValueRef {
         let lua = self.lua.lock();
         unsafe { ffi::lua_topointer(lua.ref_thread(), self.index) }
     }
-
-    /// Returns a copy of the value, which is valid as long as the original value is held.
-    #[inline]
-    pub(crate) fn copy(&self) -> Self {
-        ValueRef {
-            lua: self.lua.clone(),
-            index: self.index,
-            drop: false,
-        }
-    }
 }
 
 impl fmt::Debug for ValueRef {
@@ -43,17 +50,15 @@ impl fmt::Debug for ValueRef {
     }
 }
 
-impl Clone for ValueRef {
-    fn clone(&self) -> Self {
-        unsafe { self.lua.lock().clone_ref(self) }
-    }
-}
-
 impl Drop for ValueRef {
     fn drop(&mut self) {
-        if self.drop {
-            if let Some(lua) = self.lua.try_lock() {
-                unsafe { lua.drop_ref(self) };
+        if let Some(ValueRefIndex(index)) = self.index_count.take() {
+            // It's guaranteed that the inner value returns exactly once.
+            // This means in particular that the value is not dropped.
+            if XRc::into_inner(index).is_some() {
+                if let Some(lua) = self.lua.try_lock() {
+                    unsafe { lua.drop_ref(self) };
+                }
             }
         }
     }

src/userdata.rs

@@ -12,7 +12,7 @@ use crate::string::String;
 use crate::table::{Table, TablePairs};
 use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti};
 use crate::types::{MaybeSend, ValueRef};
-use crate::util::{check_stack, get_userdata, push_string, take_userdata, StackGuard};
+use crate::util::{check_stack, get_userdata, push_string, short_type_name, take_userdata, StackGuard};
 use crate::value::Value;
 
 #[cfg(feature = "async")]
@@ -56,32 +56,53 @@ pub enum MetaMethod {
     /// The unary minus (`-`) operator.
     Unm,
     /// The floor division (//) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau")))
+    )]
     IDiv,
     /// The bitwise AND (&) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53")))
+    )]
     BAnd,
     /// The bitwise OR (|) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53")))
+    )]
     BOr,
     /// The bitwise XOR (binary ~) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53")))
+    )]
     BXor,
     /// The bitwise NOT (unary ~) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53")))
+    )]
     BNot,
     /// The bitwise left shift (<<) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53")))
+    )]
     Shl,
     /// The bitwise right shift (>>) operator.
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "lua53"))))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "lua55", feature = "lua54", feature = "lua53")))
+    )]
     Shr,
     /// The string concatenation operator `..`.
     Concat,
@@ -106,10 +127,22 @@ pub enum MetaMethod {
     /// The `__pairs` metamethod.
     ///
     /// This is not an operator, but it will be called by the built-in `pairs` function.
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luajit52"))]
+    #[cfg(any(
+        feature = "lua55",
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52",
+        feature = "luajit52"
+    ))]
     #[cfg_attr(
         docsrs,
-        doc(cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luajit52")))
+        doc(cfg(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "luajit52"
+        )))
     )]
     Pairs,
     /// The `__ipairs` metamethod.
@@ -135,8 +168,8 @@ pub enum MetaMethod {
     /// [documentation][lua_doc].
     ///
     /// [lua_doc]: https://www.lua.org/manual/5.4/manual.html#3.3.8
-    #[cfg(feature = "lua54")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "lua54")))]
+    #[cfg(any(feature = "lua55", feature = "lua54"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
     Close,
     /// The `__name`/`__type` metafield.
     ///
@@ -176,19 +209,19 @@ impl MetaMethod {
             MetaMethod::Pow => "__pow",
             MetaMethod::Unm => "__unm",
 
-            #[cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau"))]
             MetaMethod::IDiv => "__idiv",
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             MetaMethod::BAnd => "__band",
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             MetaMethod::BOr => "__bor",
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             MetaMethod::BXor => "__bxor",
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             MetaMethod::BNot => "__bnot",
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             MetaMethod::Shl => "__shl",
-            #[cfg(any(feature = "lua54", feature = "lua53"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             MetaMethod::Shr => "__shr",
 
             MetaMethod::Concat => "__concat",
@@ -201,14 +234,20 @@ impl MetaMethod {
             MetaMethod::Call => "__call",
             MetaMethod::ToString => "__tostring",
 
-            #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luajit52"))]
+            #[cfg(any(
+                feature = "lua55",
+                feature = "lua54",
+                feature = "lua53",
+                feature = "lua52",
+                feature = "luajit52"
+            ))]
             MetaMethod::Pairs => "__pairs",
             #[cfg(any(feature = "lua52", feature = "luajit52"))]
             MetaMethod::IPairs => "__ipairs",
             #[cfg(feature = "luau")]
             MetaMethod::Iter => "__iter",
 
-            #[cfg(feature = "lua54")]
+            #[cfg(any(feature = "lua55", feature = "lua54"))]
             MetaMethod::Close => "__close",
 
             #[rustfmt::skip]
@@ -240,6 +279,13 @@ impl AsRef<str> for MetaMethod {
     }
 }
 
+impl From<MetaMethod> for StdString {
+    #[inline]
+    fn from(method: MetaMethod) -> Self {
+        method.name().to_owned()
+    }
+}
+
 /// Method registry for [`UserData`] implementors.
 pub trait UserDataMethods<T> {
     /// Add a regular method which accepts a `&T` as the first parameter.
@@ -249,7 +295,7 @@ pub trait UserDataMethods<T> {
     ///
     /// If `add_meta_method` is used to set the `__index` metamethod, the `__index` metamethod will
     /// be used as a fall-back if no regular method is found.
-    fn add_method<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_method<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -260,12 +306,35 @@ pub trait UserDataMethods<T> {
     /// Refer to [`add_method`] for more information about the implementation.
     ///
     /// [`add_method`]: UserDataMethods::add_method
-    fn add_method_mut<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_method_mut<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti;
 
+    /// Add a method which accepts `T` as the first parameter.
+    ///
+    /// The userdata `T` will be moved out of the userdata container. This is useful for
+    /// methods that need to consume the userdata.
+    ///
+    /// The method can be called only once per userdata instance, subsequent calls will result in a
+    /// [`Error::UserDataDestructed`] error.
+    #[doc(hidden)]
+    fn add_method_once<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
+    where
+        T: 'static,
+        M: Fn(&Lua, T, A) -> Result<R> + MaybeSend + 'static,
+        A: FromLuaMulti,
+        R: IntoLuaMulti,
+    {
+        let name = name.into();
+        let method_name = format!("{}.{name}", short_type_name::<T>());
+        self.add_function(name, move |lua, (ud, args): (AnyUserData, A)| {
+            let this = (ud.take()).map_err(|err| Error::bad_self_argument(&method_name, err))?;
+            method(lua, this, args)
+        });
+    }
+
     /// Add an async method which accepts a `&T` as the first parameter and returns [`Future`].
     ///
     /// Refer to [`add_method`] for more information about the implementation.
@@ -273,7 +342,7 @@ pub trait UserDataMethods<T> {
     /// [`add_method`]: UserDataMethods::add_method
     #[cfg(feature = "async")]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn add_async_method<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_method<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -288,7 +357,7 @@ pub trait UserDataMethods<T> {
     /// [`add_method`]: UserDataMethods::add_method
     #[cfg(feature = "async")]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -296,12 +365,40 @@ pub trait UserDataMethods<T> {
         MR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti;
 
+    /// Add an async method which accepts a `T` as the first parameter and returns [`Future`].
+    ///
+    /// The userdata `T` will be moved out of the userdata container. This is useful for
+    /// methods that need to consume the userdata.
+    ///
+    /// The method can be called only once per userdata instance, subsequent calls will result in a
+    /// [`Error::UserDataDestructed`] error.
+    #[cfg(feature = "async")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
+    #[doc(hidden)]
+    fn add_async_method_once<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
+    where
+        T: 'static,
+        M: Fn(Lua, T, A) -> MR + MaybeSend + 'static,
+        A: FromLuaMulti,
+        MR: Future<Output = Result<R>> + MaybeSend + 'static,
+        R: IntoLuaMulti,
+    {
+        let name = name.into();
+        let method_name = format!("{}.{name}", short_type_name::<T>());
+        self.add_async_function(name, move |lua, (ud, args): (AnyUserData, A)| {
+            match (ud.take()).map_err(|err| Error::bad_self_argument(&method_name, err)) {
+                Ok(this) => either::Either::Left(method(lua, this, args)),
+                Err(err) => either::Either::Right(async move { Err(err) }),
+            }
+        });
+    }
+
     /// Add a regular method as a function which accepts generic arguments.
     ///
     /// The first argument will 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)`.
-    fn add_function<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_function<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -312,7 +409,7 @@ pub trait UserDataMethods<T> {
     /// This is a version of [`add_function`] that accepts a `FnMut` argument.
     ///
     /// [`add_function`]: UserDataMethods::add_function
-    fn add_function_mut<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_function_mut<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -326,7 +423,7 @@ pub trait UserDataMethods<T> {
     /// [`add_function`]: UserDataMethods::add_function
     #[cfg(feature = "async")]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn add_async_function<F, A, FR, R>(&mut self, name: impl ToString, function: F)
+    fn add_async_function<F, A, FR, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(Lua, A) -> FR + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -341,7 +438,7 @@ pub trait UserDataMethods<T> {
     /// side has a metatable. To prevent this, use [`add_meta_function`].
     ///
     /// [`add_meta_function`]: UserDataMethods::add_meta_function
-    fn add_meta_method<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_meta_method<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -355,7 +452,7 @@ pub trait UserDataMethods<T> {
     /// side has a metatable. To prevent this, use [`add_meta_function`].
     ///
     /// [`add_meta_function`]: UserDataMethods::add_meta_function
-    fn add_meta_method_mut<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_meta_method_mut<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -371,7 +468,7 @@ pub trait UserDataMethods<T> {
         docsrs,
         doc(cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau")))))
     )]
-    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -387,7 +484,7 @@ pub trait UserDataMethods<T> {
     /// [`add_meta_method_mut`]: UserDataMethods::add_meta_method_mut
     #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -400,7 +497,7 @@ pub trait UserDataMethods<T> {
     /// 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<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_meta_function<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -411,7 +508,7 @@ pub trait UserDataMethods<T> {
     /// This is a version of [`add_meta_function`] that accepts a `FnMut` argument.
     ///
     /// [`add_meta_function`]: UserDataMethods::add_meta_function
-    fn add_meta_function_mut<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_meta_function_mut<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -427,7 +524,7 @@ pub trait UserDataMethods<T> {
         docsrs,
         doc(cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau")))))
     )]
-    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl ToString, function: F)
+    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(Lua, A) -> FR + MaybeSend + 'static,
         A: FromLuaMulti,
@@ -446,7 +543,7 @@ pub trait UserDataFields<T> {
     ///
     /// If `add_meta_method` is used to set the `__index` metamethod, it will
     /// be used as a fall-back if no regular field or method are found.
-    fn add_field<V>(&mut self, name: impl ToString, value: V)
+    fn add_field<V>(&mut self, name: impl Into<StdString>, value: V)
     where
         V: IntoLua + 'static;
 
@@ -457,7 +554,7 @@ pub trait UserDataFields<T> {
     ///
     /// 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<M, R>(&mut self, name: impl ToString, method: M)
+    fn add_field_method_get<M, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: Fn(&Lua, &T) -> Result<R> + MaybeSend + 'static,
         R: IntoLua;
@@ -470,21 +567,21 @@ pub trait UserDataFields<T> {
     ///
     /// 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<M, A>(&mut self, name: impl ToString, method: M)
+    fn add_field_method_set<M, A>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: FnMut(&Lua, &mut T, A) -> Result<()> + MaybeSend + 'static,
         A: FromLua;
 
     /// Add a regular field getter as a function which accepts a generic [`AnyUserData`] of type `T`
     /// argument.
-    fn add_field_function_get<F, R>(&mut self, name: impl ToString, function: F)
+    fn add_field_function_get<F, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(&Lua, AnyUserData) -> Result<R> + MaybeSend + 'static,
         R: IntoLua;
 
     /// Add a regular field setter as a function which accepts a generic [`AnyUserData`] of type `T`
     /// first argument.
-    fn add_field_function_set<F, A>(&mut self, name: impl ToString, function: F)
+    fn add_field_function_set<F, A>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: FnMut(&Lua, AnyUserData, A) -> Result<()> + MaybeSend + 'static,
         A: FromLua;
@@ -497,7 +594,7 @@ pub trait UserDataFields<T> {
     ///
     /// `mlua` will trigger an error on an attempt to define a protected metamethod,
     /// like `__gc` or `__metatable`.
-    fn add_meta_field<V>(&mut self, name: impl ToString, value: V)
+    fn add_meta_field<V>(&mut self, name: impl Into<StdString>, value: V)
     where
         V: IntoLua + 'static;
 
@@ -509,7 +606,7 @@ pub trait UserDataFields<T> {
     ///
     /// `mlua` will trigger an error on an attempt to define a protected metamethod,
     /// like `__gc` or `__metatable`.
-    fn add_meta_field_with<F, R>(&mut self, name: impl ToString, f: F)
+    fn add_meta_field_with<F, R>(&mut self, name: impl Into<StdString>, f: F)
     where
         F: FnOnce(&Lua) -> Result<R> + 'static,
         R: IntoLua;
@@ -621,6 +718,14 @@ impl AnyUserData {
         matches!(type_id, Some(type_id) if type_id == TypeId::of::<T>())
     }
 
+    /// Checks whether the type of this userdata is a [proxy object] for `T`.
+    ///
+    /// [proxy object]: crate::Lua::create_proxy
+    #[inline]
+    pub fn is_proxy<T: 'static>(&self) -> bool {
+        self.is::<UserDataProxy<T>>()
+    }
+
     /// Borrow this userdata immutably if it is of type `T`.
     ///
     /// # Errors
@@ -881,16 +986,17 @@ impl AnyUserData {
         self.raw_metatable().map(UserDataMetatable)
     }
 
+    /// Returns a raw metatable of this [`AnyUserData`].
     fn raw_metatable(&self) -> Result<Table> {
         let lua = self.0.lua.lock();
-        let state = lua.state();
+        let ref_thread = lua.ref_thread();
         unsafe {
-            let _sg = StackGuard::new(state);
-            check_stack(state, 3)?;
+            // Check that userdata is registered and not destructed
+            // All registered userdata types have a non-empty metatable
+            let _type_id = lua.get_userdata_ref_type_id(&self.0)?;
 
-            lua.push_userdata_ref(&self.0)?;
-            ffi::lua_getmetatable(state, -1); // Checked that non-empty on the previous call
-            Ok(Table(lua.pop_ref()))
+            ffi::lua_getmetatable(ref_thread, self.0.index);
+            Ok(Table(lua.pop_ref_thread()))
         }
     }
 
@@ -913,8 +1019,10 @@ impl AnyUserData {
         lua.get_userdata_ref_type_id(&self.0).ok().flatten()
     }
 
-    /// Returns a type name of this `UserData` (from a metatable field).
-    pub(crate) fn type_name(&self) -> Result<Option<StdString>> {
+    /// Returns a type name of this userdata (from a metatable field).
+    ///
+    /// If no type name is set, returns `None`.
+    pub fn type_name(&self) -> Result<Option<StdString>> {
         let lua = self.0.lua.lock();
         let state = lua.state();
         unsafe {
@@ -1008,7 +1116,7 @@ impl UserDataMetatable {
     /// The pairs are wrapped in a [`Result`], since they are lazily converted to `V` type.
     ///
     /// [`Result`]: crate::Result
-    pub fn pairs<V: FromLua>(&self) -> UserDataMetatablePairs<V> {
+    pub fn pairs<V: FromLua>(&self) -> UserDataMetatablePairs<'_, V> {
         UserDataMetatablePairs(self.0.pairs())
     }
 }

src/userdata/object.rs

@@ -1,6 +1,7 @@
 use std::string::String as StdString;
 
 use crate::error::{Error, Result};
+use crate::state::WeakLua;
 use crate::table::Table;
 use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti, ObjectLike};
 use crate::userdata::AnyUserData;
@@ -8,21 +9,21 @@ use crate::value::Value;
 use crate::Function;
 
 #[cfg(feature = "async")]
-use futures_util::future::{self, Either, Future};
+use crate::function::AsyncCallFuture;
 
 impl ObjectLike for AnyUserData {
     #[inline]
     fn get<V: FromLua>(&self, key: impl IntoLua) -> Result<V> {
         // `lua_gettable` method used under the hood can work with any Lua value
         // that has `__index` metamethod
-        Table(self.0.copy()).get_protected(key)
+        Table(self.0.clone()).get_protected(key)
     }
 
     #[inline]
     fn set(&self, key: impl IntoLua, value: impl IntoLua) -> Result<()> {
         // `lua_settable` method used under the hood can work with any Lua value
         // that has `__newindex` metamethod
-        Table(self.0.copy()).set_protected(key, value)
+        Table(self.0.clone()).set_protected(key, value)
     }
 
     #[inline]
@@ -30,16 +31,16 @@ impl ObjectLike for AnyUserData {
     where
         R: FromLuaMulti,
     {
-        Function(self.0.copy()).call(args)
+        Function(self.0.clone()).call(args)
     }
 
     #[cfg(feature = "async")]
     #[inline]
-    fn call_async<R>(&self, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async<R>(&self, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti,
     {
-        Function(self.0.copy()).call_async(args)
+        Function(self.0.clone()).call_async(args)
     }
 
     #[inline]
@@ -51,7 +52,7 @@ impl ObjectLike for AnyUserData {
     }
 
     #[cfg(feature = "async")]
-    fn call_async_method<R>(&self, name: &str, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async_method<R>(&self, name: &str, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti,
     {
@@ -72,22 +73,32 @@ impl ObjectLike for AnyUserData {
     }
 
     #[cfg(feature = "async")]
-    fn call_async_function<R>(&self, name: &str, args: impl IntoLuaMulti) -> impl Future<Output = Result<R>>
+    fn call_async_function<R>(&self, name: &str, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
     where
         R: FromLuaMulti,
     {
         match self.get(name) {
-            Ok(Value::Function(func)) => Either::Left(func.call_async(args)),
+            Ok(Value::Function(func)) => func.call_async(args),
             Ok(val) => {
                 let msg = format!("attempt to call a {} value (function '{name}')", val.type_name());
-                Either::Right(future::ready(Err(Error::RuntimeError(msg))))
+                AsyncCallFuture::error(Error::RuntimeError(msg))
             }
-            Err(err) => Either::Right(future::ready(Err(err))),
+            Err(err) => AsyncCallFuture::error(err),
         }
     }
 
     #[inline]
     fn to_string(&self) -> Result<StdString> {
-        Value::UserData(AnyUserData(self.0.copy())).to_string()
+        Value::UserData(self.clone()).to_string()
+    }
+
+    #[inline]
+    fn to_value(&self) -> Value {
+        Value::UserData(self.clone())
+    }
+
+    #[inline]
+    fn weak_lua(&self) -> &WeakLua {
+        &self.0.lua
     }
 }

src/userdata/ref.rs

@@ -63,7 +63,7 @@ impl<T> TryFrom<UserDataVariant<T>> for UserDataRef<T> {
 
     #[inline]
     fn try_from(variant: UserDataVariant<T>) -> Result<Self> {
-        let guard = if !cfg!(feature = "send") || is_sync::<T>() {
+        let guard = if cfg!(not(feature = "send")) || is_sync::<T>() {
             variant.raw_lock().try_lock_shared_guarded()
         } else {
             variant.raw_lock().try_lock_exclusive_guarded()

src/userdata/registry.rs

@@ -56,6 +56,9 @@ pub(crate) struct RawUserDataRegistry {
     pub(crate) destructor: ffi::lua_CFunction,
     pub(crate) type_id: Option<TypeId>,
     pub(crate) type_name: StdString,
+
+    #[cfg(feature = "luau")]
+    pub(crate) enable_namecall: bool,
 }
 
 impl UserDataType {
@@ -100,6 +103,8 @@ impl<T> UserDataRegistry<T> {
             destructor: super::util::destroy_userdata_storage::<T>,
             type_id: r#type.type_id(),
             type_name: short_type_name::<T>(),
+            #[cfg(feature = "luau")]
+            enable_namecall: false,
         };
 
         UserDataRegistry {
@@ -110,6 +115,23 @@ impl<T> UserDataRegistry<T> {
         }
     }
 
+    /// Enables support for the namecall optimization in Luau.
+    ///
+    /// This enables methods resolution optimization in Luau for complex userdata types with methods
+    /// and field getters. When enabled, Luau will use a faster lookup path for method calls when a
+    /// specific syntax is used (e.g. `obj:method()`.
+    ///
+    /// This optimization does not play well with async methods, custom `__index` metamethod and
+    /// field getters as functions. So, it is disabled by default.
+    ///
+    /// Use with caution.
+    #[doc(hidden)]
+    #[cfg(feature = "luau")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub fn enable_namecall(&mut self) {
+        self.raw.enable_namecall = true;
+    }
+
     fn box_method<M, A, R>(&self, name: &str, method: M) -> Callback
     where
         M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
@@ -365,101 +387,101 @@ fn get_function_name<T>(name: &str) -> StdString {
 }
 
 impl<T> UserDataFields<T> for UserDataRegistry<T> {
-    fn add_field<V>(&mut self, name: impl ToString, value: V)
+    fn add_field<V>(&mut self, name: impl Into<StdString>, value: V)
     where
         V: IntoLua + 'static,
     {
-        let name = name.to_string();
+        let name = name.into();
         self.raw.fields.push((name, value.into_lua(self.lua.lua())));
     }
 
-    fn add_field_method_get<M, R>(&mut self, name: impl ToString, method: M)
+    fn add_field_method_get<M, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: Fn(&Lua, &T) -> Result<R> + MaybeSend + 'static,
         R: IntoLua,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_method(&name, move |lua, data, ()| method(lua, data));
         self.raw.field_getters.push((name, callback));
     }
 
-    fn add_field_method_set<M, A>(&mut self, name: impl ToString, method: M)
+    fn add_field_method_set<M, A>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: FnMut(&Lua, &mut T, A) -> Result<()> + MaybeSend + 'static,
         A: FromLua,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_method_mut(&name, method);
         self.raw.field_setters.push((name, callback));
     }
 
-    fn add_field_function_get<F, R>(&mut self, name: impl ToString, function: F)
+    fn add_field_function_get<F, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(&Lua, AnyUserData) -> Result<R> + MaybeSend + 'static,
         R: IntoLua,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_function(&name, function);
         self.raw.field_getters.push((name, callback));
     }
 
-    fn add_field_function_set<F, A>(&mut self, name: impl ToString, mut function: F)
+    fn add_field_function_set<F, A>(&mut self, name: impl Into<StdString>, mut function: F)
     where
         F: FnMut(&Lua, AnyUserData, A) -> Result<()> + MaybeSend + 'static,
         A: FromLua,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_function_mut(&name, move |lua, (data, val)| function(lua, data, val));
         self.raw.field_setters.push((name, callback));
     }
 
-    fn add_meta_field<V>(&mut self, name: impl ToString, value: V)
+    fn add_meta_field<V>(&mut self, name: impl Into<StdString>, value: V)
     where
         V: IntoLua + 'static,
     {
         let lua = self.lua.lua();
-        let name = name.to_string();
+        let name = name.into();
         let field = Self::check_meta_field(lua, &name, value).and_then(|v| v.into_lua(lua));
         self.raw.meta_fields.push((name, field));
     }
 
-    fn add_meta_field_with<F, R>(&mut self, name: impl ToString, f: F)
+    fn add_meta_field_with<F, R>(&mut self, name: impl Into<StdString>, f: F)
     where
         F: FnOnce(&Lua) -> Result<R> + 'static,
         R: IntoLua,
     {
         let lua = self.lua.lua();
-        let name = name.to_string();
+        let name = name.into();
         let field = f(lua).and_then(|v| Self::check_meta_field(lua, &name, v).and_then(|v| v.into_lua(lua)));
         self.raw.meta_fields.push((name, field));
     }
 }
 
 impl<T> UserDataMethods<T> for UserDataRegistry<T> {
-    fn add_method<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_method<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_method(&name, method);
         self.raw.methods.push((name, callback));
     }
 
-    fn add_method_mut<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_method_mut<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_method_mut(&name, method);
         self.raw.methods.push((name, callback));
     }
 
     #[cfg(feature = "async")]
-    fn add_async_method<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_method<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -467,13 +489,13 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
         MR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_async_method(&name, method);
         self.raw.async_methods.push((name, callback));
     }
 
     #[cfg(feature = "async")]
-    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -481,70 +503,70 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
         MR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_async_method_mut(&name, method);
         self.raw.async_methods.push((name, callback));
     }
 
-    fn add_function<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_function<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_function(&name, function);
         self.raw.methods.push((name, callback));
     }
 
-    fn add_function_mut<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_function_mut<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_function_mut(&name, function);
         self.raw.methods.push((name, callback));
     }
 
     #[cfg(feature = "async")]
-    fn add_async_function<F, A, FR, R>(&mut self, name: impl ToString, function: F)
+    fn add_async_function<F, A, FR, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(Lua, A) -> FR + MaybeSend + 'static,
         A: FromLuaMulti,
         FR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_async_function(&name, function);
         self.raw.async_methods.push((name, callback));
     }
 
-    fn add_meta_method<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_meta_method<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_method(&name, method);
         self.raw.meta_methods.push((name, callback));
     }
 
-    fn add_meta_method_mut<M, A, R>(&mut self, name: impl ToString, method: M)
+    fn add_meta_method_mut<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_method_mut(&name, method);
         self.raw.meta_methods.push((name, callback));
     }
 
     #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
-    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -552,13 +574,13 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
         MR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_async_method(&name, method);
         self.raw.async_meta_methods.push((name, callback));
     }
 
     #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
-    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl ToString, method: M)
+    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
     where
         T: 'static,
         M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -566,42 +588,42 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
         MR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_async_method_mut(&name, method);
         self.raw.async_meta_methods.push((name, callback));
     }
 
-    fn add_meta_function<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_meta_function<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_function(&name, function);
         self.raw.meta_methods.push((name, callback));
     }
 
-    fn add_meta_function_mut<F, A, R>(&mut self, name: impl ToString, function: F)
+    fn add_meta_function_mut<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
         A: FromLuaMulti,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_function_mut(&name, function);
         self.raw.meta_methods.push((name, callback));
     }
 
     #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
-    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl ToString, function: F)
+    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl Into<StdString>, function: F)
     where
         F: Fn(Lua, A) -> FR + MaybeSend + 'static,
         A: FromLuaMulti,
         FR: Future<Output = Result<R>> + MaybeSend + 'static,
         R: IntoLuaMulti,
     {
-        let name = name.to_string();
+        let name = name.into();
         let callback = self.box_async_function(&name, function);
         self.raw.async_meta_methods.push((name, callback));
     }

src/userdata/util.rs

@@ -4,8 +4,11 @@ use std::marker::PhantomData;
 use std::os::raw::c_int;
 use std::ptr;
 
+use rustc_hash::FxHashMap;
+
 use super::UserDataStorage;
 use crate::error::{Error, Result};
+use crate::types::CallbackPtr;
 use crate::util::{get_userdata, rawget_field, rawset_field, take_userdata};
 
 // This is a trick to check if a type is `Sync` or not.
@@ -244,6 +247,7 @@ pub(crate) unsafe fn init_userdata_metatable(
     field_getters: Option<c_int>,
     field_setters: Option<c_int>,
     methods: Option<c_int>,
+    _methods_map: Option<FxHashMap<Vec<u8>, CallbackPtr>>, // Used only in Luau for `__namecall`
 ) -> Result<()> {
     if field_getters.is_some() || methods.is_some() {
         // Push `__index` generator function
@@ -267,6 +271,13 @@ pub(crate) unsafe fn init_userdata_metatable(
         }
 
         rawset_field(state, metatable, "__index")?;
+
+        #[cfg(feature = "luau")]
+        if let Some(methods_map) = _methods_map {
+            // In Luau we can speedup method calls by providing a dedicated `__namecall` metamethod
+            push_userdata_metatable_namecall(state, methods_map)?;
+            rawset_field(state, metatable, "__namecall")?;
+        }
     }
 
     if let Some(field_setters) = field_setters {
@@ -425,6 +436,36 @@ unsafe fn init_userdata_metatable_newindex(state: *mut ffi::lua_State) -> Result
     })
 }
 
+#[cfg(feature = "luau")]
+unsafe fn push_userdata_metatable_namecall(
+    state: *mut ffi::lua_State,
+    methods_map: FxHashMap<Vec<u8>, CallbackPtr>,
+) -> Result<()> {
+    unsafe extern "C-unwind" fn namecall(state: *mut ffi::lua_State) -> c_int {
+        let name = ffi::lua_namecallatom(state, ptr::null_mut());
+        if name.is_null() {
+            ffi::luaL_error(state, cstr!("attempt to call an unknown method"));
+        }
+        let name_cs = std::ffi::CStr::from_ptr(name);
+        let methods_map = get_userdata::<FxHashMap<Vec<u8>, CallbackPtr>>(state, ffi::lua_upvalueindex(1));
+        let callback_ptr = match (*methods_map).get(name_cs.to_bytes()) {
+            Some(ptr) => *ptr,
+            #[rustfmt::skip]
+            None => ffi::luaL_error(state, cstr!("attempt to call an unknown method '%s'"), name),
+        };
+        crate::state::callback_error_ext(state, ptr::null_mut(), true, |extra, nargs| {
+            let rawlua = (*extra).raw_lua();
+            (*callback_ptr)(rawlua, nargs)
+        })
+    }
+
+    // Automatic destructor is provided for any Luau userdata
+    crate::util::push_userdata(state, methods_map, true)?;
+    protect_lua!(state, 1, 1, |state| {
+        ffi::lua_pushcclosured(state, namecall, cstr!("__namecall"), 1);
+    })
+}
+
 // This method is called by Lua GC when it's time to collect the userdata.
 //
 // This method is usually used to collect internal userdata.

src/util/error.rs

@@ -208,7 +208,7 @@ where
         F: FnOnce(*mut ffi::lua_State) -> R,
         R: Copy,
     {
-        let params = ffi::lua_touserdata(state, -1) as *mut Params<F, R>;
+        let params = ffi::lua_tolightuserdata(state, -1) as *mut Params<F, R>;
         ffi::lua_pop(state, 1);
 
         let f = (*params).function.take().unwrap();
@@ -239,7 +239,7 @@ where
 
     ffi::lua_pushlightuserdata(state, &mut params as *mut Params<F, R> as *mut c_void);
     let ret = ffi::lua_pcall(state, nargs + 1, nresults, stack_start + 1);
-    ffi::lua_remove(state, stack_start + 1);
+    ffi::lua_remove(state, stack_start + 1); // remove error handler
 
     if ret == ffi::LUA_OK {
         // `LUA_OK` is only returned when the `do_call` function has completed successfully, so
@@ -373,19 +373,19 @@ pub(crate) unsafe fn init_error_registry(state: *mut ffi::lua_State) -> Result<(
         "__mod",
         "__pow",
         "__unm",
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "luau"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "luau"))]
         "__idiv",
-        #[cfg(any(feature = "lua54", feature = "lua53"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
         "__band",
-        #[cfg(any(feature = "lua54", feature = "lua53"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
         "__bor",
-        #[cfg(any(feature = "lua54", feature = "lua53"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
         "__bxor",
-        #[cfg(any(feature = "lua54", feature = "lua53"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
         "__bnot",
-        #[cfg(any(feature = "lua54", feature = "lua53"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
         "__shl",
-        #[cfg(any(feature = "lua54", feature = "lua53"))]
+        #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
         "__shr",
         "__concat",
         "__len",
@@ -396,13 +396,21 @@ pub(crate) unsafe fn init_error_registry(state: *mut ffi::lua_State) -> Result<(
         "__newindex",
         "__call",
         "__tostring",
-        #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", feature = "luajit52"))]
+        #[cfg(any(
+            feature = "lua55",
+            feature = "lua54",
+            feature = "lua53",
+            feature = "lua52",
+            feature = "luajit52"
+        ))]
         "__pairs",
         #[cfg(any(feature = "lua53", feature = "lua52", feature = "luajit52"))]
         "__ipairs",
         #[cfg(feature = "luau")]
         "__iter",
-        #[cfg(feature = "lua54")]
+        #[cfg(feature = "luau")]
+        "__namecall",
+        #[cfg(any(feature = "lua55", feature = "lua54"))]
         "__close",
     ] {
         ffi::lua_pushvalue(state, -1);

src/util/mod.rs

@@ -9,6 +9,7 @@ pub(crate) use error::{
     error_traceback, error_traceback_thread, init_error_registry, pop_error, protect_lua_call,
     protect_lua_closure, WrappedFailure,
 };
+pub(crate) use path::parse_path as parse_lookup_path;
 pub(crate) use short_names::short_type_name;
 pub(crate) use types::TypeKey;
 pub(crate) use userdata::{
@@ -88,7 +89,7 @@ impl Drop for StackGuard {
 #[inline(always)]
 pub(crate) unsafe fn push_string(state: *mut ffi::lua_State, s: &[u8], protect: bool) -> Result<()> {
     // Always use protected mode if the string is too long
-    if protect || s.len() > (1 << 30) {
+    if protect || s.len() >= const { 1 << 30 } {
         protect_lua!(state, 0, 1, |state| {
             ffi::lua_pushlstring(state, s.as_ptr() as *const c_char, s.len());
         })
@@ -98,18 +99,48 @@ pub(crate) unsafe fn push_string(state: *mut ffi::lua_State, s: &[u8], protect:
     }
 }
 
+// Uses 3 (or 1 if unprotected) stack spaces, does not call checkstack.
+#[cfg(feature = "lua55")]
+pub(crate) unsafe fn push_external_string(
+    state: *mut ffi::lua_State,
+    mut bytes: Vec<u8>,
+    protect: bool,
+) -> Result<()> {
+    bytes.push(0);
+    let s_len = bytes.len() - 1; // exclude null terminator
+    let s_ptr = bytes.as_ptr() as *const c_char;
+    let bytes_ud = Box::into_raw(Box::new(bytes));
+
+    unsafe extern "C" fn dealloc(ud: *mut c_void, _: *mut c_void, _: usize, _: usize) -> *mut c_void {
+        drop(Box::from_raw(ud as *mut Vec<u8>));
+        ptr::null_mut()
+    }
+
+    if protect {
+        let res = protect_lua!(state, 0, 1, move |state| {
+            ffi::lua_pushexternalstring(state, s_ptr, s_len, Some(dealloc), bytes_ud as *mut _);
+        });
+        if res.is_err() {
+            // Deallocate on error
+            drop(Box::from_raw(bytes_ud));
+            return res;
+        }
+    } else {
+        ffi::lua_pushexternalstring(state, s_ptr, s_len, Some(dealloc), bytes_ud as *mut _);
+    }
+    Ok(())
+}
+
 // Uses 3 stack spaces (when protect), does not call checkstack.
 #[cfg(feature = "luau")]
 #[inline(always)]
-pub(crate) unsafe fn push_buffer(state: *mut ffi::lua_State, b: &[u8], protect: bool) -> Result<()> {
-    let data = if protect {
-        protect_lua!(state, 0, 1, |state| ffi::lua_newbuffer(state, b.len()))?
+pub(crate) unsafe fn push_buffer(state: *mut ffi::lua_State, size: usize, protect: bool) -> Result<*mut u8> {
+    let data = if protect || size > const { 1024 * 1024 * 1024 } {
+        protect_lua!(state, 0, 1, |state| ffi::lua_newbuffer(state, size))?
     } else {
-        ffi::lua_newbuffer(state, b.len())
+        ffi::lua_newbuffer(state, size)
     };
-    let buf = slice::from_raw_parts_mut(data as *mut u8, b.len());
-    buf.copy_from_slice(b);
-    Ok(())
+    Ok(data as *mut u8)
 }
 
 // Uses 3 stack spaces, does not call checkstack.
@@ -122,7 +153,7 @@ pub(crate) unsafe fn push_table(
 ) -> Result<()> {
     let narr: c_int = narr.try_into().unwrap_or(c_int::MAX);
     let nrec: c_int = nrec.try_into().unwrap_or(c_int::MAX);
-    if protect {
+    if protect || narr >= const { 1 << 26 } || nrec >= const { 1 << 26 } {
         protect_lua!(state, 0, 1, |state| ffi::lua_createtable(state, narr, nrec))
     } else {
         ffi::lua_createtable(state, narr, nrec);
@@ -221,7 +252,7 @@ pub(crate) unsafe extern "C-unwind" fn safe_xpcall(state: *mut ffi::lua_State) -
 // Returns Lua main thread for Lua >= 5.2 or checks that the passed thread is main for Lua 5.1.
 // Does not call lua_checkstack, uses 1 stack space.
 pub(crate) unsafe fn get_main_state(state: *mut ffi::lua_State) -> Option<*mut ffi::lua_State> {
-    #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
     {
         ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_RIDX_MAINTHREAD);
         let main_state = ffi::lua_tothread(state, -1);
@@ -329,6 +360,7 @@ pub(crate) fn linenumber_to_usize(n: c_int) -> Option<usize> {
 }
 
 mod error;
+mod path;
 mod short_names;
 mod types;
 mod userdata;

src/util/path.rs

@@ -0,0 +1,255 @@
+use std::borrow::Cow;
+use std::fmt;
+use std::iter::Peekable;
+use std::str::CharIndices;
+
+use crate::error::{Error, Result};
+use crate::state::Lua;
+use crate::traits::IntoLua;
+use crate::types::Integer;
+use crate::value::Value;
+
+#[derive(Debug)]
+pub(crate) enum PathKey<'a> {
+    Str(Cow<'a, str>),
+    Int(Integer),
+}
+
+impl fmt::Display for PathKey<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            PathKey::Str(s) => write!(f, "{}", s),
+            PathKey::Int(i) => write!(f, "{}", i),
+        }
+    }
+}
+
+impl IntoLua for PathKey<'_> {
+    fn into_lua(self, lua: &Lua) -> Result<Value> {
+        match self {
+            PathKey::Str(s) => Ok(Value::String(lua.create_string(s.as_ref())?)),
+            PathKey::Int(i) => Ok(Value::Integer(i)),
+        }
+    }
+}
+
+// Parses a path like `a.b[3]?.c["d"]` into segments of `(key, safe_nil)`.
+pub(crate) fn parse_path<'a>(path: &'a str) -> Result<Vec<(PathKey<'a>, bool)>> {
+    fn read_ident<'a>(path: &'a str, chars: &mut Peekable<CharIndices<'a>>) -> (Cow<'a, str>, bool) {
+        let mut safe_nil = false;
+        let start = chars.peek().map(|&(i, _)| i).unwrap_or(path.len());
+        let mut end = start;
+        while let Some(&(pos, c)) = chars.peek() {
+            if c == '.' || c == '?' || c.is_ascii_whitespace() || c == '[' {
+                if c == '?' {
+                    safe_nil = true;
+                    chars.next(); // consume '?'
+                }
+                break;
+            }
+            end = pos + c.len_utf8();
+            chars.next();
+        }
+        (Cow::Borrowed(&path[start..end]), safe_nil)
+    }
+
+    let mut segments = Vec::new();
+    let mut chars = path.char_indices().peekable();
+    while let Some(&(pos, next)) = chars.peek() {
+        match next {
+            '.' => {
+                // Dot notation: identifier
+                chars.next();
+                let (key, safe_nil) = read_ident(path, &mut chars);
+                if key.is_empty() {
+                    return Err(Error::runtime(format!("empty key in path at position {pos}")));
+                }
+                segments.push((PathKey::Str(key), safe_nil));
+            }
+            '[' => {
+                // Bracket notation: either integer or quoted string
+                chars.next();
+                let key = match chars.peek() {
+                    Some(&(pos, c @ '0'..='9' | c @ '-')) => {
+                        // Integer key
+                        let negative = c == '-';
+                        if negative {
+                            chars.next(); // consume '-'
+                        }
+                        let mut num: Option<Integer> = None;
+                        while let Some(&(_, c @ '0'..='9')) = chars.peek() {
+                            let new_num = num
+                                .unwrap_or(0)
+                                .checked_mul(10)
+                                .and_then(|n| n.checked_add((c as u8 - b'0') as Integer))
+                                .ok_or_else(|| {
+                                    Error::runtime(format!("integer overflow in path at position {pos}"))
+                                })?;
+                            num = Some(new_num);
+                            chars.next(); // consume digit
+                        }
+                        match num {
+                            Some(n) if negative => PathKey::Int(-n),
+                            Some(n) => PathKey::Int(n),
+                            None => {
+                                let err = format!("invalid integer in path at position {pos}");
+                                return Err(Error::runtime(err));
+                            }
+                        }
+                    }
+                    Some((_, '\'' | '"')) => {
+                        // Quoted string
+                        PathKey::Str(unquote_string(path, &mut chars)?)
+                    }
+                    Some((_, ']')) => {
+                        return Err(Error::runtime(format!("empty key in path at position {pos}")));
+                    }
+                    Some((pos, c)) => {
+                        let err = format!("unexpected character '{c}' in path at position {pos}");
+                        return Err(Error::runtime(err));
+                    }
+                    None => {
+                        return Err(Error::runtime("unexpected end of path"));
+                    }
+                };
+                // Expect closing bracket
+                let mut safe_nil = false;
+                match chars.next() {
+                    Some((_, ']')) => {
+                        // Check for optional safe-nil operator
+                        if let Some(&(_, '?')) = chars.peek() {
+                            safe_nil = true;
+                            chars.next(); // consume '?'
+                        }
+                    }
+                    Some((pos, c)) => {
+                        let err = format!("expected ']' in path at position {pos}, found '{c}'");
+                        return Err(Error::runtime(err));
+                    }
+                    None => {
+                        return Err(Error::runtime("unexpected end of path"));
+                    }
+                }
+                segments.push((key, safe_nil));
+            }
+            c if c.is_ascii_whitespace() => {
+                chars.next(); // Skip whitespace
+            }
+            _ if segments.is_empty() => {
+                // First segment without dot/bracket notation
+                let (key_cow, safe_nil) = read_ident(path, &mut chars);
+                if key_cow.is_empty() {
+                    return Err(Error::runtime(format!("empty key in path at position {pos}")));
+                }
+                segments.push((PathKey::Str(key_cow), safe_nil));
+            }
+            c => {
+                let err = format!("unexpected character '{c}' in path at position {pos}");
+                return Err(Error::runtime(err));
+            }
+        }
+    }
+    Ok(segments)
+}
+
+fn unquote_string<'a>(path: &'a str, chars: &mut Peekable<CharIndices<'a>>) -> Result<Cow<'a, str>> {
+    let (start_pos, first_quote) = chars.next().unwrap();
+    let mut result = String::new();
+    loop {
+        match chars.next() {
+            Some((pos, '\\')) => {
+                if result.is_empty() {
+                    // First escape found, copy everything up to this point
+                    result.push_str(&path[start_pos + 1..pos]);
+                }
+                match chars.next() {
+                    Some((_, '\\')) => result.push('\\'),
+                    Some((_, '"')) => result.push('"'),
+                    Some((_, '\'')) => result.push('\''),
+                    Some((_, other)) => {
+                        result.push('\\');
+                        result.push(other);
+                    }
+                    None => continue, // will be handled by outer loop
+                }
+            }
+            Some((pos, c)) if c == first_quote => {
+                if !result.is_empty() {
+                    return Ok(Cow::Owned(result));
+                }
+                // No escapes, return borrowed slice
+                return Ok(Cow::Borrowed(&path[start_pos + 1..pos]));
+            }
+            Some((_, c)) => {
+                if !result.is_empty() {
+                    result.push(c);
+                }
+                // If no escapes yet, continue tracking for potential borrowed slice
+            }
+            None => {
+                let err = format!("unexpected end of string at position {start_pos}");
+                return Err(Error::runtime(err));
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{parse_path, PathKey};
+
+    #[test]
+    fn test_parse_path() {
+        // Test valid paths
+        let path = parse_path("a.b[3]?.c['d']").unwrap();
+        assert_eq!(path.len(), 5);
+        assert!(matches!(path[0], (PathKey::Str(ref s), false) if s == "a"));
+        assert!(matches!(path[1], (PathKey::Str(ref s), false) if s == "b"));
+        assert!(matches!(path[2], (PathKey::Int(3), true)));
+        assert!(matches!(path[3], (PathKey::Str(ref s), false) if s == "c"));
+        assert!(matches!(path[4], (PathKey::Str(ref s), false) if s == "d"));
+
+        // Test empty path
+        let path = parse_path("").unwrap();
+        assert_eq!(path.len(), 0);
+        let path = parse_path("   ").unwrap();
+        assert_eq!(path.len(), 0);
+
+        // Test invalid dot syntax
+        let err = parse_path("a..b").unwrap_err().to_string();
+        assert_eq!(err, "runtime error: empty key in path at position 1");
+        let err = parse_path("a.b.").unwrap_err().to_string();
+        assert_eq!(err, "runtime error: empty key in path at position 3");
+
+        // Test invalid bracket syntax
+        let err = parse_path("a[unclosed").unwrap_err().to_string();
+        assert_eq!(
+            err,
+            "runtime error: unexpected character 'u' in path at position 2"
+        );
+        let err = parse_path("a[]").unwrap_err().to_string();
+        assert_eq!(err, "runtime error: empty key in path at position 1");
+        let err = parse_path(r#"a["unclosed"#).unwrap_err().to_string();
+        assert_eq!(err, "runtime error: unexpected end of string at position 2");
+        let err = parse_path(r#"a["#).unwrap_err().to_string();
+        assert_eq!(err, "runtime error: unexpected end of path");
+        let err = parse_path(r#"a[123"#).unwrap_err().to_string();
+        assert_eq!(err, "runtime error: unexpected end of path");
+        let err = parse_path(r#"a['bla'123"#).unwrap_err().to_string();
+        assert_eq!(
+            err,
+            "runtime error: expected ']' in path at position 7, found '1'"
+        );
+        let err = parse_path(r#"a["bla"]x"#).unwrap_err().to_string();
+        assert_eq!(
+            err,
+            "runtime error: unexpected character 'x' in path at position 8"
+        );
+
+        // Test bad integers
+        let err = parse_path("a[99999999999999999999]").unwrap_err().to_string();
+        assert_eq!(err, "runtime error: integer overflow in path at position 2");
+        let err = parse_path("a[-]").unwrap_err().to_string();
+        assert_eq!(err, "runtime error: invalid integer in path at position 2");
+    }
+}

src/util/short_names.rs

@@ -1,6 +1,6 @@
-//! Mostly copied from [bevy_utils]
+//! Inspired by bevy's [disqualified]
 //!
-//! [bevy_utils]: https://github.com/bevyengine/bevy/blob/main/crates/bevy_utils/src/short_names.rs
+//! [disqualified]: https://github.com/bevyengine/disqualified/blob/main/src/short_name.rs
 
 use std::any::type_name;
 
@@ -23,8 +23,7 @@ pub(crate) fn short_type_name<T: ?Sized>() -> String {
     while index < end_of_string {
         let rest_of_string = full_name.get(index..end_of_string).unwrap_or_default();
 
-        // Collapse everything up to the next special character,
-        // then skip over it
+        // Collapse everything up to the next special character, then skip over it
         if let Some(special_character_index) =
             rest_of_string.find(|c: char| [' ', '<', '>', '(', ')', '[', ']', ',', ';'].contains(&c))
         {
@@ -32,11 +31,16 @@ pub(crate) fn short_type_name<T: ?Sized>() -> String {
             parsed_name += collapse_type_name(segment_to_collapse);
             // Insert the special character
             let special_character = &rest_of_string[special_character_index..=special_character_index];
-            parsed_name.push_str(special_character);
+            parsed_name += special_character;
+
+            // Remove lifetimes like <'_> or <'_, '_, ...>
+            if parsed_name.ends_with("<'_>") || parsed_name.ends_with("<'_, ") {
+                _ = parsed_name.split_off(parsed_name.len() - 4);
+            }
 
             match special_character {
                 ">" | ")" | "]" if rest_of_string[special_character_index + 1..].starts_with("::") => {
-                    parsed_name.push_str("::");
+                    parsed_name += "::";
                     // Move the index past the "::"
                     index += special_character_index + 3;
                 }
@@ -53,14 +57,18 @@ pub(crate) fn short_type_name<T: ?Sized>() -> String {
 }
 
 #[inline(always)]
-fn collapse_type_name(string: &str) -> &str {
-    string.rsplit("::").next().unwrap()
+fn collapse_type_name(segment: &str) -> &str {
+    segment.rsplit("::").next().unwrap()
 }
 
 #[cfg(test)]
 mod tests {
     use super::short_type_name;
     use std::collections::HashMap;
+    use std::marker::PhantomData;
+
+    struct MyData<'a, 'b>(PhantomData<&'a &'b ()>);
+    struct MyDataT<'a, T>(PhantomData<&'a T>);
 
     #[test]
     fn tests() {
@@ -73,5 +81,7 @@ mod tests {
             "HashMap<String, Option<[i32; 3]>>"
         );
         assert_eq!(short_type_name::<dyn Fn(i32) -> i32>(), "dyn Fn(i32) -> i32");
+        assert_eq!(short_type_name::<MyDataT<&str>>(), "MyDataT<&str>");
+        assert_eq!(short_type_name::<(&MyData, [MyData])>(), "(MyData, [MyData])");
     }
 }

src/util/userdata.rs

@@ -73,7 +73,7 @@ pub(crate) unsafe fn init_internal_metatable<T: TypeKey>(
     Ok(())
 }
 
-// Uses 2 stack spaces, does not call checkstack
+// Uses up to 1 stack space, does not call `checkstack`
 pub(crate) unsafe fn get_internal_userdata<T: TypeKey>(
     state: *mut ffi::lua_State,
     index: c_int,

src/value.rs

@@ -28,9 +28,10 @@ use {
 /// The non-primitive variants (eg. string/table/function/thread/userdata) 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(Clone)]
+#[derive(Clone, Default)]
 pub enum Value {
     /// The Lua value `nil`.
+    #[default]
     Nil,
     /// The Lua value `true` or `false`.
     Boolean(bool),
@@ -356,14 +357,22 @@ impl Value {
     ///
     /// If the value is a Lua [`String`], try to convert it to [`BorrowedStr`] or return `None`
     /// otherwise.
+    #[deprecated(
+        since = "0.11.0",
+        note = "This method does not follow Rust naming convention. Use `as_string().and_then(|s| s.to_str().ok())` instead."
+    )]
     #[inline]
-    pub fn as_str(&self) -> Option<BorrowedStr> {
+    pub fn as_str(&self) -> Option<BorrowedStr<'_>> {
         self.as_string().and_then(|s| s.to_str().ok())
     }
 
     /// Cast the value to [`StdString`].
     ///
     /// If the value is a Lua [`String`], converts it to [`StdString`] or returns `None` otherwise.
+    #[deprecated(
+        since = "0.11.0",
+        note = "This method does not follow Rust naming convention. Use `as_string().map(|s| s.to_string_lossy())` instead."
+    )]
     #[inline]
     pub fn as_string_lossy(&self) -> Option<StdString> {
         self.as_string().map(|s| s.to_string_lossy())
@@ -483,8 +492,7 @@ impl Value {
     /// This allows customizing serialization behavior using serde.
     #[cfg(feature = "serde")]
     #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
-    #[doc(hidden)]
-    pub fn to_serializable(&self) -> SerializableValue {
+    pub fn to_serializable(&self) -> SerializableValue<'_> {
         SerializableValue::new(self, Default::default(), None)
     }
 
@@ -572,12 +580,6 @@ impl Value {
     }
 }
 
-impl Default for Value {
-    fn default() -> Self {
-        Self::Nil
-    }
-}
-
 impl fmt::Debug for Value {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         if fmt.alternate() {
@@ -676,7 +678,7 @@ impl<'a> SerializableValue<'a> {
     ///
     /// Default: **true**
     #[must_use]
-    pub const fn deny_unsupported_types(mut self, enabled: bool) -> Self {
+    pub fn deny_unsupported_types(mut self, enabled: bool) -> Self {
         self.options.deny_unsupported_types = enabled;
         self
     }
@@ -687,7 +689,7 @@ impl<'a> SerializableValue<'a> {
     ///
     /// Default: **true**
     #[must_use]
-    pub const fn deny_recursive_tables(mut self, enabled: bool) -> Self {
+    pub fn deny_recursive_tables(mut self, enabled: bool) -> Self {
         self.options.deny_recursive_tables = enabled;
         self
     }
@@ -696,7 +698,7 @@ impl<'a> SerializableValue<'a> {
     ///
     /// Default: **false**
     #[must_use]
-    pub const fn sort_keys(mut self, enabled: bool) -> Self {
+    pub fn sort_keys(mut self, enabled: bool) -> Self {
         self.options.sort_keys = enabled;
         self
     }
@@ -705,10 +707,21 @@ impl<'a> SerializableValue<'a> {
     ///
     /// Default: **false**
     #[must_use]
-    pub const fn encode_empty_tables_as_array(mut self, enabled: bool) -> Self {
+    pub fn encode_empty_tables_as_array(mut self, enabled: bool) -> Self {
         self.options.encode_empty_tables_as_array = enabled;
         self
     }
+
+    /// If true, enable detection of mixed tables.
+    ///
+    /// A mixed table is a table that has both array-like and map-like entries or several borders.
+    ///
+    /// Default: **false**
+    #[must_use]
+    pub fn detect_mixed_tables(mut self, enabled: bool) -> Self {
+        self.options.detect_mixed_tables = enabled;
+        self
+    }
 }
 
 #[cfg(feature = "serde")]

tarpaulin.toml

@@ -1,11 +1,11 @@
-[lua54]
-features = "lua54,vendored,async,send,serde,macros,anyhow,userdata-wrappers"
+[lua55]
+features = "lua55,vendored,async,send,serde,macros,anyhow,userdata-wrappers"
 
-[lua54_non_send]
-features = "lua54,vendored,async,serde,macros,anyhow,userdata-wrappers"
+[lua55_non_send]
+features = "lua55,vendored,async,serde,macros,anyhow,userdata-wrappers"
 
-[lua54_with_memory_limit]
-features = "lua54,vendored,async,send,serde,macros,anyhow,userdata-wrappers"
+[lua55_with_memory_limit]
+features = "lua55,vendored,async,send,serde,macros,anyhow,userdata-wrappers"
 rustflags = "--cfg force_memory_limit"
 
 [lua51]

tests/async.rs

@@ -8,7 +8,7 @@ use futures_util::stream::TryStreamExt;
 use tokio::sync::Mutex;
 
 use mlua::{
-    Error, Function, Lua, LuaOptions, MultiValue, ObjectLike, Result, StdLib, Table, UserData,
+    Error, Function, Lua, LuaOptions, MultiValue, ObjectLike, Result, StdLib, Table, ThreadStatus, UserData,
     UserDataMethods, UserDataRef, Value,
 };
 
@@ -249,7 +249,7 @@ async fn test_async_return_async_closure() -> Result<()> {
     Ok(())
 }
 
-#[cfg(feature = "lua54")]
+#[cfg(any(feature = "lua55", feature = "lua54"))]
 #[tokio::test]
 async fn test_async_lua54_to_be_closed() -> Result<()> {
     let lua = Lua::new();
@@ -386,7 +386,7 @@ async fn test_async_table_object_like() -> Result<()> {
             table.get::<i64>("val")
         })?,
     )?;
-    table.set_metatable(Some(metatable));
+    table.set_metatable(Some(metatable))?;
     assert_eq!(table.call_async::<i64>(()).await.unwrap(), 15);
 
     match table.call_async_method::<()>("non_existent", ()).await {
@@ -423,9 +423,9 @@ async fn test_async_thread_pool() -> Result<()> {
 
 #[tokio::test]
 async fn test_async_userdata() -> Result<()> {
-    struct MyUserData(u64);
+    struct MyUserdata(u64);
 
-    impl UserData for MyUserData {
+    impl UserData for MyUserdata {
         fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
             methods.add_async_method("get_value", |_, data, ()| async move {
                 sleep_ms(10).await;
@@ -438,6 +438,11 @@ async fn test_async_userdata() -> Result<()> {
                 Ok(())
             });
 
+            methods.add_async_method_once("take_value", |_, data, ()| async move {
+                sleep_ms(10).await;
+                Ok(data.0)
+            });
+
             methods.add_async_function("sleep", |_, n| async move {
                 sleep_ms(n).await;
                 Ok(format!("elapsed:{}ms", n))
@@ -479,7 +484,7 @@ async fn test_async_userdata() -> Result<()> {
     let lua = Lua::new();
     let globals = lua.globals();
 
-    let userdata = lua.create_userdata(MyUserData(11))?;
+    let userdata = lua.create_userdata(MyUserdata(11))?;
     globals.set("userdata", &userdata)?;
 
     lua.load(
@@ -518,6 +523,21 @@ async fn test_async_userdata() -> Result<()> {
     #[cfg(not(any(feature = "lua51", feature = "luau")))]
     assert_eq!(userdata.call_async::<String>(()).await?, "elapsed:24ms");
 
+    // Take value
+    let userdata2 = lua.create_userdata(MyUserdata(0))?;
+    globals.set("userdata2", userdata2)?;
+    lua.load("assert(userdata:take_value() == 24)")
+        .exec_async()
+        .await?;
+    match lua.load("userdata2.take_value(userdata)").exec_async().await {
+        Err(Error::CallbackError { cause, .. }) => {
+            let err = cause.to_string();
+            assert!(err.contains("bad argument `self` to `MyUserdata.take_value`"));
+            assert!(err.contains("userdata has been destructed"));
+        }
+        r => panic!("expected Err(CallbackError), got {r:?}"),
+    }
+
     Ok(())
 }
 
@@ -610,6 +630,36 @@ async fn test_async_task() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn test_async_task_abort() -> Result<()> {
+    let lua = Lua::new();
+
+    let sleep = lua.create_async_function(move |_lua, n: u64| async move {
+        sleep_ms(n).await;
+        Ok(())
+    })?;
+    lua.globals().set("sleep", sleep)?;
+
+    let local = tokio::task::LocalSet::new();
+    local
+        .run_until(async {
+            let lua2 = lua.clone();
+            let jh = tokio::task::spawn_local(async move {
+                lua2.load("sleep(200) result = 'done'")
+                    .exec_async()
+                    .await
+                    .unwrap();
+            });
+            sleep_ms(100).await; // Wait for the task to start
+            jh.abort();
+        })
+        .await;
+    local.await;
+    assert_eq!(lua.globals().get::<Value>("result")?, Value::Nil);
+
+    Ok(())
+}
+
 #[tokio::test]
 #[cfg(not(feature = "luau"))]
 async fn test_async_hook() -> Result<()> {
@@ -620,7 +670,7 @@ async fn test_async_hook() -> Result<()> {
     static HOOK_CALLED: AtomicBool = AtomicBool::new(false);
     lua.set_global_hook(mlua::HookTriggers::new().every_line(), move |_, _| {
         if !HOOK_CALLED.swap(true, Ordering::Relaxed) {
-            #[cfg(any(feature = "lu53", feature = "lua54"))]
+            #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
             return Ok(mlua::VmState::Yield);
         }
         Ok(mlua::VmState::Continue)
@@ -637,3 +687,35 @@ async fn test_async_hook() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_async_yield_with() -> Result<()> {
+    let lua = Lua::new();
+
+    let func = lua.create_async_function(|lua, (mut a, mut b): (i32, i32)| async move {
+        let zero = lua.yield_with::<MultiValue>(()).await?;
+        assert!(zero.is_empty());
+        let one = lua.yield_with::<MultiValue>(a + b).await?;
+        assert_eq!(one.len(), 1);
+
+        for _ in 0..3 {
+            (a, b) = lua.yield_with((a + b, a * b)).await?;
+        }
+        Ok((0, 0))
+    })?;
+
+    let thread = lua.create_thread(func)?;
+
+    let zero = thread.resume::<MultiValue>((2, 3))?; // function arguments
+    assert!(zero.is_empty());
+    let one = thread.resume::<i32>(())?; // value of "zero" is passed here
+    assert_eq!(one, 5);
+
+    assert_eq!(thread.resume::<(i32, i32)>(1)?, (5, 6)); // value of "one" is passed here
+    assert_eq!(thread.resume::<(i32, i32)>((10, 11))?, (21, 110));
+    assert_eq!(thread.resume::<(i32, i32)>((11, 12))?, (23, 132));
+    assert_eq!(thread.resume::<(i32, i32)>((12, 13))?, (0, 0));
+    assert_eq!(thread.status(), ThreadStatus::Finished);
+
+    Ok(())
+}

tests/buffer.rs

@@ -1,5 +1,7 @@
 #![cfg(feature = "luau")]
 
+use std::io::{Read, Seek, SeekFrom, Write};
+
 use mlua::{Lua, Result, Value};
 
 #[test]
@@ -41,7 +43,7 @@ fn test_buffer() -> Result<()> {
 }
 
 #[test]
-#[should_panic(expected = "range end index 14 out of range for slice of length 13")]
+#[should_panic(expected = "out of range for slice of length 13")]
 fn test_buffer_out_of_bounds_read() {
     let lua = Lua::new();
     let buf = lua.create_buffer(b"hello, world!").unwrap();
@@ -49,9 +51,73 @@ fn test_buffer_out_of_bounds_read() {
 }
 
 #[test]
-#[should_panic(expected = "range end index 16 out of range for slice of length 13")]
+#[should_panic(expected = "out of range for slice of length 13")]
 fn test_buffer_out_of_bounds_write() {
     let lua = Lua::new();
     let buf = lua.create_buffer(b"hello, world!").unwrap();
     buf.write_bytes(14, b"!!");
 }
+
+#[test]
+fn create_large_buffer() {
+    let lua = Lua::new();
+    let err = lua.create_buffer_with_capacity(1_073_741_824 + 1).unwrap_err(); // 1GB
+    assert!(err.to_string().contains("memory allocation error"));
+
+    // Normal buffer is okay
+    let buf = lua.create_buffer_with_capacity(1024 * 1024).unwrap();
+    assert_eq!(buf.len(), 1024 * 1024);
+}
+
+#[test]
+fn test_buffer_cursor() -> Result<()> {
+    let lua = Lua::new();
+    let mut cursor = lua.create_buffer(b"hello, world")?.cursor();
+
+    let mut data = Vec::new();
+    cursor.read_to_end(&mut data)?;
+    assert_eq!(data, b"hello, world");
+
+    // No more data to read
+    let mut one = [0u8; 1];
+    assert_eq!(cursor.read(&mut one)?, 0);
+
+    // Seek to start
+    cursor.seek(SeekFrom::Start(0))?;
+    cursor.read_exact(&mut one)?;
+    assert_eq!(one, [b'h']);
+
+    // Seek to end -5
+    cursor.seek(SeekFrom::End(-5))?;
+    let mut five = [0u8; 5];
+    cursor.read_exact(&mut five)?;
+    assert_eq!(&five, b"world");
+
+    // Seek to current -1
+    cursor.seek(SeekFrom::Current(-1))?;
+    cursor.read_exact(&mut one)?;
+    assert_eq!(one, [b'd']);
+
+    // Invalid seek
+    assert!(cursor.seek(SeekFrom::Current(-100)).is_err());
+    assert!(cursor.seek(SeekFrom::End(1)).is_err());
+
+    // Write data
+    let buf = lua.create_buffer_with_capacity(100)?;
+    cursor = buf.clone().cursor();
+
+    cursor.write_all(b"hello, ...")?;
+    cursor.seek(SeekFrom::Current(-3))?;
+    cursor.write_all(b"Rust!")?;
+
+    assert_eq!(&buf.read_bytes::<12>(0), b"hello, Rust!");
+
+    // Writing beyond the end of the buffer does nothing
+    cursor.seek(SeekFrom::End(0))?;
+    assert_eq!(cursor.write(b".")?, 0);
+
+    // Flush is no-op
+    cursor.flush()?;
+
+    Ok(())
+}

tests/chunk.rs

@@ -21,6 +21,7 @@ fn test_chunk_methods() -> Result<()> {
 }
 
 #[test]
+#[cfg(not(target_os = "wasi"))]
 fn test_chunk_path() -> Result<()> {
     let lua = Lua::new();
 
@@ -119,12 +120,11 @@ fn test_compiler() -> Result<()> {
         .set_debug_level(2)
         .set_type_info_level(1)
         .set_coverage_level(2)
-        .set_vector_lib("vector")
-        .set_vector_ctor("new")
+        .set_vector_ctor("vector.new")
         .set_vector_type("vector")
-        .set_mutable_globals(vec!["mutable_global"])
-        .set_userdata_types(vec!["MyUserdata"])
-        .set_disabled_builtins(vec!["tostring"]);
+        .set_mutable_globals(["mutable_global"])
+        .set_userdata_types(["MyUserdata"])
+        .set_disabled_builtins(["tostring"]);
 
     assert!(compiler.compile("return tostring(vector.new(1, 2, 3))").is_ok());
 
@@ -142,16 +142,14 @@ fn test_compiler() -> Result<()> {
 #[cfg(feature = "luau")]
 #[test]
 fn test_compiler_library_constants() {
-    use mlua::{CompileConstant, Compiler, Vector};
+    use mlua::{Compiler, Vector};
 
     let compiler = Compiler::new()
         .set_optimization_level(2)
-        .set_library_constants(vec![
-            ("mylib", "const_bool", CompileConstant::Boolean(true)),
-            ("mylib", "const_num", CompileConstant::Number(123.0)),
-            ("mylib", "const_vec", CompileConstant::Vector(Vector::zero())),
-            ("mylib", "const_str", "value1".into()),
-        ]);
+        .add_library_constant("mylib.const_bool", true)
+        .add_library_constant("mylib.const_num", 123.0)
+        .add_library_constant("mylib.const_vec", Vector::zero())
+        .add_library_constant("mylib.const_str", "value1");
 
     let lua = Lua::new();
     lua.set_compiler(compiler);

tests/compile/async_any_userdata_method.stderr

@@ -1,15 +1,19 @@
 error[E0596]: cannot borrow `s` as mutable, as it is a captured variable in a `Fn` closure
   --> tests/compile/async_any_userdata_method.rs:9:49
    |
-9  |         reg.add_async_method("t", |_, this, ()| async {
-   |                                                 ^^^^^ cannot borrow as mutable
+ 8 |         let mut s = &s;
+   |             ----- `s` declared here, outside the closure
+ 9 |         reg.add_async_method("t", |_, this, ()| async {
+   |                                   ------------- ^^^^^ cannot borrow as mutable
+   |                                   |
+   |                                   in this closure
 10 |             s = &*this;
    |             - mutable borrow occurs due to use of `s` in closure
 
 error[E0373]: async block may outlive the current function, but it borrows `this`, which is owned by the current function
   --> tests/compile/async_any_userdata_method.rs:9:49
    |
-9  |         reg.add_async_method("t", |_, this, ()| async {
+ 9 |         reg.add_async_method("t", |_, this, ()| async {
    |                                                 ^^^^^ may outlive borrowed value `this`
 10 |             s = &*this;
    |                   ---- `this` is borrowed here
@@ -17,7 +21,7 @@ error[E0373]: async block may outlive the current function, but it borrows `this
 note: async block is returned here
   --> tests/compile/async_any_userdata_method.rs:9:49
    |
-9  |           reg.add_async_method("t", |_, this, ()| async {
+ 9 |           reg.add_async_method("t", |_, this, ()| async {
    |  _________________________________________________^
 10 | |             s = &*this;
 11 | |             Ok(())
@@ -25,13 +29,13 @@ note: async block is returned here
    | |_________^
 help: to force the async block to take ownership of `this` (and any other referenced variables), use the `move` keyword
    |
-9  |         reg.add_async_method("t", |_, this, ()| async move {
+ 9 |         reg.add_async_method("t", |_, this, ()| async move {
    |                                                       ++++
 
 error: lifetime may not live long enough
   --> tests/compile/async_any_userdata_method.rs:9:49
    |
-9  |           reg.add_async_method("t", |_, this, ()| async {
+ 9 |           reg.add_async_method("t", |_, this, ()| async {
    |  ___________________________________-------------_^
    | |                                   |           |
    | |                                   |           return type of closure `{async block@$DIR/tests/compile/async_any_userdata_method.rs:9:49: 9:54}` contains a lifetime `'2`
@@ -46,22 +50,28 @@ error: lifetime may not live long enough
 error[E0597]: `s` does not live long enough
   --> tests/compile/async_any_userdata_method.rs:8:21
    |
-7  |           let s = String::new();
+ 7 |           let s = String::new();
    |               - binding `s` declared here
-8  |           let mut s = &s;
+ 8 |           let mut s = &s;
    |                       ^^ borrowed value does not live long enough
-9  | /         reg.add_async_method("t", |_, this, ()| async {
+ 9 | /         reg.add_async_method("t", |_, this, ()| async {
 10 | |             s = &*this;
 11 | |             Ok(())
 12 | |         });
    | |__________- argument requires that `s` is borrowed for `'static`
 13 |       })
    |       - `s` dropped here while still borrowed
+   |
+note: requirement that the value outlives `'static` introduced here
+  --> src/userdata.rs
+   |
+   |         M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
+   |                                                           ^^^^^^^
 
 error[E0373]: closure may outlive the current function, but it borrows `s`, which is owned by the current function
   --> tests/compile/async_any_userdata_method.rs:9:35
    |
-9  |         reg.add_async_method("t", |_, this, ()| async {
+ 9 |         reg.add_async_method("t", |_, this, ()| async {
    |                                   ^^^^^^^^^^^^^ may outlive borrowed value `s`
 10 |             s = &*this;
    |             - `s` is borrowed here
@@ -69,12 +79,12 @@ error[E0373]: closure may outlive the current function, but it borrows `s`, whic
 note: function requires argument type to outlive `'static`
   --> tests/compile/async_any_userdata_method.rs:9:9
    |
-9  | /         reg.add_async_method("t", |_, this, ()| async {
+ 9 | /         reg.add_async_method("t", |_, this, ()| async {
 10 | |             s = &*this;
 11 | |             Ok(())
 12 | |         });
    | |__________^
 help: to force the closure to take ownership of `s` (and any other referenced variables), use the `move` keyword
    |
-9  |         reg.add_async_method("t", move |_, this, ()| async {
+ 9 |         reg.add_async_method("t", move |_, this, ()| async {
    |                                   ++++

tests/compile/async_nonstatic_userdata.stderr

@@ -1,10 +1,10 @@
 error: lifetime may not live long enough
   --> tests/compile/async_nonstatic_userdata.rs:9:13
    |
-7  |       impl UserData for MyUserData<'_> {
+ 7 |       impl UserData for MyUserData<'_> {
    |                                    -- lifetime `'1` appears in the `impl`'s self type
-8  |           fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
-9  | /             methods.add_async_method("print", |_, data, ()| async move {
+ 8 |           fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
+ 9 | /             methods.add_async_method("print", |_, data, ()| async move {
 10 | |                 println!("{}", data.0);
 11 | |                 Ok(())
 12 | |             });

tests/compile/lua_norefunwindsafe.stderr

@@ -1,28 +1,32 @@
-error[E0277]: the type `UnsafeCell<*mut lua_State>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+error[E0277]: the type `UnsafeCell<mlua::state::raw::RawLua>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
  --> tests/compile/lua_norefunwindsafe.rs:7:18
   |
 7 |     catch_unwind(|| lua.create_table().unwrap());
-  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<*mut lua_State>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<mlua::state::raw::RawLua>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
   |     |
   |     required by a bound introduced by this call
   |
-  = help: within `mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<*mut lua_State>`
-note: required because it appears within the type `Cell<*mut lua_State>`
- --> $RUST/core/src/cell.rs
+  = help: within `Lua`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<mlua::state::raw::RawLua>`
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>`
+ --> $CARGO/lock_api-$VERSION/src/remutex.rs
   |
-  | pub struct Cell<T: ?Sized> {
-  |            ^^^^
-note: required because it appears within the type `mlua::state::raw::RawLua`
- --> src/state/raw.rs
+  | pub struct ReentrantMutex<R, G, T: ?Sized> {
+  |            ^^^^^^^^^^^^^^
+note: required because it appears within the type `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
   |
-  | pub struct RawLua {
-  |            ^^^^^^
-note: required because it appears within the type `mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>`
- --> src/types/sync.rs
+  | struct ArcInner<T: ?Sized> {
+  |        ^^^^^^^^
+note: required because it appears within the type `PhantomData<alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>>`
+ --> $RUST/core/src/marker.rs
   |
-  |     pub(crate) struct ReentrantMutex<T>(T);
-  |                       ^^^^^^^^^^^^^^
-  = note: required for `Rc<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>` to implement `RefUnwindSafe`
+  | pub struct PhantomData<T: PointeeSized>;
+  |            ^^^^^^^^^^^
+note: required because it appears within the type `Arc<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
+  |
+  | pub struct Arc<
+  |            ^^^
 note: required because it appears within the type `Lua`
  --> src/state.rs
   |
@@ -40,27 +44,45 @@ note: required by a bound in `std::panic::catch_unwind`
   | pub fn catch_unwind<F: FnOnce() -> R + UnwindSafe, R>(f: F) -> Result<R> {
   |                                        ^^^^^^^^^^ required by this bound in `catch_unwind`
 
-error[E0277]: the type `UnsafeCell<mlua::state::extra::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+error[E0277]: the type `UnsafeCell<usize>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
  --> tests/compile/lua_norefunwindsafe.rs:7:18
   |
 7 |     catch_unwind(|| lua.create_table().unwrap());
-  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<mlua::state::extra::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<usize>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
   |     |
   |     required by a bound introduced by this call
   |
-  = help: the trait `RefUnwindSafe` is not implemented for `UnsafeCell<mlua::state::extra::ExtraData>`
-  = note: required for `Rc<UnsafeCell<mlua::state::extra::ExtraData>>` to implement `RefUnwindSafe`
-note: required because it appears within the type `mlua::state::raw::RawLua`
- --> src/state/raw.rs
+  = help: within `Lua`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<usize>`
+note: required because it appears within the type `Cell<usize>`
+ --> $RUST/core/src/cell.rs
   |
-  | pub struct RawLua {
-  |            ^^^^^^
-note: required because it appears within the type `mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>`
- --> src/types/sync.rs
+  | pub struct Cell<T: ?Sized> {
+  |            ^^^^
+note: required because it appears within the type `lock_api::remutex::RawReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId>`
+ --> $CARGO/lock_api-$VERSION/src/remutex.rs
   |
-  |     pub(crate) struct ReentrantMutex<T>(T);
-  |                       ^^^^^^^^^^^^^^
-  = note: required for `Rc<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>` to implement `RefUnwindSafe`
+  | pub struct RawReentrantMutex<R, G> {
+  |            ^^^^^^^^^^^^^^^^^
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>`
+ --> $CARGO/lock_api-$VERSION/src/remutex.rs
+  |
+  | pub struct ReentrantMutex<R, G, T: ?Sized> {
+  |            ^^^^^^^^^^^^^^
+note: required because it appears within the type `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
+  |
+  | struct ArcInner<T: ?Sized> {
+  |        ^^^^^^^^
+note: required because it appears within the type `PhantomData<alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>>`
+ --> $RUST/core/src/marker.rs
+  |
+  | pub struct PhantomData<T: PointeeSized>;
+  |            ^^^^^^^^^^^
+note: required because it appears within the type `Arc<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
+  |
+  | pub struct Arc<
+  |            ^^^
 note: required because it appears within the type `Lua`
  --> src/state.rs
   |

tests/compile/ref_nounwindsafe.stderr

@@ -1,143 +1,86 @@
-error[E0277]: the type `UnsafeCell<usize>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+error[E0277]: the type `UnsafeCell<mlua::state::raw::RawLua>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
  --> tests/compile/ref_nounwindsafe.rs:8:18
   |
 8 |     catch_unwind(move || table.set("a", "b").unwrap());
-  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<usize>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
+  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<mlua::state::raw::RawLua>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
   |     |
   |     required by a bound introduced by this call
   |
-  = help: within `rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<usize>`
+  = help: within `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<mlua::state::raw::RawLua>`
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>`
+ --> $CARGO/lock_api-$VERSION/src/remutex.rs
+  |
+  | pub struct ReentrantMutex<R, G, T: ?Sized> {
+  |            ^^^^^^^^^^^^^^
+note: required because it appears within the type `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
+  |
+  | struct ArcInner<T: ?Sized> {
+  |        ^^^^^^^^
+  = note: required for `NonNull<alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>>` to implement `UnwindSafe`
+note: required because it appears within the type `std::sync::Weak<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
+  |
+  | pub struct Weak<
+  |            ^^^^
+note: required because it appears within the type `WeakLua`
+ --> src/state.rs
+  |
+  | pub struct WeakLua(XWeak<ReentrantMutex<RawLua>>);
+  |            ^^^^^^^
+note: required because it appears within the type `mlua::types::value_ref::ValueRef`
+ --> src/types/value_ref.rs
+  |
+  | pub struct ValueRef {
+  |            ^^^^^^^^
+note: required because it appears within the type `LuaTable`
+ --> src/table.rs
+  |
+  | pub struct Table(pub(crate) ValueRef);
+  |            ^^^^^
+note: required because it's used within this closure
+ --> tests/compile/ref_nounwindsafe.rs:8:18
+  |
+8 |     catch_unwind(move || table.set("a", "b").unwrap());
+  |                  ^^^^^^^
+note: required by a bound in `std::panic::catch_unwind`
+ --> $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`
+
+error[E0277]: the type `UnsafeCell<usize>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
+ --> tests/compile/ref_nounwindsafe.rs:8:18
+  |
+8 |     catch_unwind(move || table.set("a", "b").unwrap());
+  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<usize>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
+  |     |
+  |     required by a bound introduced by this call
+  |
+  = help: within `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<usize>`
 note: required because it appears within the type `Cell<usize>`
  --> $RUST/core/src/cell.rs
   |
   | pub struct Cell<T: ?Sized> {
   |            ^^^^
-note: required because it appears within the type `rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`
- --> $RUST/alloc/src/rc.rs
+note: required because it appears within the type `lock_api::remutex::RawReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId>`
+ --> $CARGO/lock_api-$VERSION/src/remutex.rs
   |
-  | struct RcInner<T: ?Sized> {
-  |        ^^^^^^^
-  = note: required for `NonNull<rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>>` to implement `UnwindSafe`
-note: required because it appears within the type `std::rc::Weak<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`
- --> $RUST/alloc/src/rc.rs
-  |
-  | pub struct Weak<
-  |            ^^^^
-note: required because it appears within the type `WeakLua`
- --> src/state.rs
-  |
-  | pub struct WeakLua(XWeak<ReentrantMutex<RawLua>>);
-  |            ^^^^^^^
-note: required because it appears within the type `mlua::types::value_ref::ValueRef`
- --> src/types/value_ref.rs
-  |
-  | pub struct ValueRef {
-  |            ^^^^^^^^
-note: required because it appears within the type `LuaTable`
- --> src/table.rs
-  |
-  | pub struct Table(pub(crate) ValueRef);
-  |            ^^^^^
-note: required because it's used within this closure
- --> tests/compile/ref_nounwindsafe.rs:8:18
-  |
-8 |     catch_unwind(move || table.set("a", "b").unwrap());
-  |                  ^^^^^^^
-note: required by a bound in `std::panic::catch_unwind`
- --> $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`
-
-error[E0277]: the type `UnsafeCell<*mut lua_State>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
- --> tests/compile/ref_nounwindsafe.rs:8:18
-  |
-8 |     catch_unwind(move || table.set("a", "b").unwrap());
-  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<*mut lua_State>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-  |     |
-  |     required by a bound introduced by this call
-  |
-  = help: within `rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<*mut lua_State>`
-note: required because it appears within the type `Cell<*mut lua_State>`
- --> $RUST/core/src/cell.rs
-  |
-  | pub struct Cell<T: ?Sized> {
-  |            ^^^^
-note: required because it appears within the type `mlua::state::raw::RawLua`
- --> src/state/raw.rs
-  |
-  | pub struct RawLua {
-  |            ^^^^^^
-note: required because it appears within the type `mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>`
- --> src/types/sync.rs
-  |
-  |     pub(crate) struct ReentrantMutex<T>(T);
-  |                       ^^^^^^^^^^^^^^
-note: required because it appears within the type `rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`
- --> $RUST/alloc/src/rc.rs
-  |
-  | struct RcInner<T: ?Sized> {
-  |        ^^^^^^^
-  = note: required for `NonNull<rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>>` to implement `UnwindSafe`
-note: required because it appears within the type `std::rc::Weak<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`
- --> $RUST/alloc/src/rc.rs
-  |
-  | pub struct Weak<
-  |            ^^^^
-note: required because it appears within the type `WeakLua`
- --> src/state.rs
-  |
-  | pub struct WeakLua(XWeak<ReentrantMutex<RawLua>>);
-  |            ^^^^^^^
-note: required because it appears within the type `mlua::types::value_ref::ValueRef`
- --> src/types/value_ref.rs
-  |
-  | pub struct ValueRef {
-  |            ^^^^^^^^
-note: required because it appears within the type `LuaTable`
- --> src/table.rs
-  |
-  | pub struct Table(pub(crate) ValueRef);
-  |            ^^^^^
-note: required because it's used within this closure
- --> tests/compile/ref_nounwindsafe.rs:8:18
-  |
-8 |     catch_unwind(move || table.set("a", "b").unwrap());
-  |                  ^^^^^^^
-note: required by a bound in `std::panic::catch_unwind`
- --> $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`
-
-error[E0277]: the type `UnsafeCell<mlua::state::extra::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
- --> tests/compile/ref_nounwindsafe.rs:8:18
-  |
-8 |     catch_unwind(move || table.set("a", "b").unwrap());
-  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<mlua::state::extra::ExtraData>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
-  |     |
-  |     required by a bound introduced by this call
-  |
-  = help: the trait `RefUnwindSafe` is not implemented for `UnsafeCell<mlua::state::extra::ExtraData>`
-  = note: required for `Rc<UnsafeCell<mlua::state::extra::ExtraData>>` to implement `RefUnwindSafe`
-note: required because it appears within the type `mlua::state::raw::RawLua`
- --> src/state/raw.rs
-  |
-  | pub struct RawLua {
-  |            ^^^^^^
-note: required because it appears within the type `mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>`
- --> src/types/sync.rs
-  |
-  |     pub(crate) struct ReentrantMutex<T>(T);
-  |                       ^^^^^^^^^^^^^^
-note: required because it appears within the type `rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`
- --> $RUST/alloc/src/rc.rs
-  |
-  | struct RcInner<T: ?Sized> {
-  |        ^^^^^^^
-  = note: required for `NonNull<rc::RcInner<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>>` to implement `UnwindSafe`
-note: required because it appears within the type `std::rc::Weak<mlua::types::sync::inner::ReentrantMutex<mlua::state::raw::RawLua>>`
- --> $RUST/alloc/src/rc.rs
+  | pub struct RawReentrantMutex<R, G> {
+  |            ^^^^^^^^^^^^^^^^^
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>`
+ --> $CARGO/lock_api-$VERSION/src/remutex.rs
+  |
+  | pub struct ReentrantMutex<R, G, T: ?Sized> {
+  |            ^^^^^^^^^^^^^^
+note: required because it appears within the type `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
+  |
+  | struct ArcInner<T: ?Sized> {
+  |        ^^^^^^^^
+  = note: required for `NonNull<alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>>` to implement `UnwindSafe`
+note: required because it appears within the type `std::sync::Weak<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::raw::RawLua>>`
+ --> $RUST/alloc/src/sync.rs
   |
   | pub struct Weak<
   |            ^^^^

tests/compile/scope_callback_capture.stderr

@@ -1,24 +1,24 @@
 error[E0373]: closure may outlive the current function, but it borrows `inner`, which is owned by the current function
   --> tests/compile/scope_callback_capture.rs:7:43
    |
-5  |     lua.scope(|scope| {
+ 5 |     lua.scope(|scope| {
    |                ----- has type `&'1 mlua::Scope<'1, '_>`
-6  |         let mut inner: Option<Table> = None;
-7  |         let f = scope.create_function_mut(|_, t: Table| {
+ 6 |         let mut inner: Option<Table> = None;
+ 7 |         let f = scope.create_function_mut(|_, t: Table| {
    |                                           ^^^^^^^^^^^^^ may outlive borrowed value `inner`
-8  |             inner = Some(t);
+ 8 |             inner = Some(t);
    |             ----- `inner` is borrowed here
    |
 note: function requires argument type to outlive `'1`
   --> tests/compile/scope_callback_capture.rs:7:17
    |
-7  |           let f = scope.create_function_mut(|_, t: Table| {
+ 7 |           let f = scope.create_function_mut(|_, t: Table| {
    |  _________________^
-8  | |             inner = Some(t);
-9  | |             Ok(())
+ 8 | |             inner = Some(t);
+ 9 | |             Ok(())
 10 | |         })?;
    | |__________^
 help: to force the closure to take ownership of `inner` (and any other referenced variables), use the `move` keyword
    |
-7  |         let f = scope.create_function_mut(move |_, t: Table| {
+ 7 |         let f = scope.create_function_mut(move |_, t: Table| {
    |                                           ++++

tests/compile/scope_invariance.stderr

@@ -1,7 +1,7 @@
 error[E0373]: closure may outlive the current function, but it borrows `test.field`, which is owned by the current function
   --> tests/compile/scope_invariance.rs:13:39
    |
-9  |     lua.scope(|scope| {
+ 9 |     lua.scope(|scope| {
    |                ----- has type `&'1 mlua::Scope<'1, '_>`
 ...
 13 |             scope.create_function_mut(|_, ()| {

tests/compile/scope_mutable_aliasing.stderr

@@ -10,3 +10,9 @@ error[E0499]: cannot borrow `i` as mutable more than once at a time
    |                  argument requires that `i` is borrowed for `'1`
 12 |         let _b = scope.create_userdata(MyUserData(&mut i)).unwrap();
    |                                                   ^^^^^^ second mutable borrow occurs here
+   |
+note: requirement that the value outlives `'1` introduced here
+  --> src/scope.rs
+   |
+   |         T: UserData + 'env,
+   |                       ^^^^

tests/compile/scope_userdata_borrow.stderr

@@ -13,3 +13,9 @@ error[E0597]: `ibad` does not live long enough
    |             argument requires that `ibad` is borrowed for `'1`
 16 |         };
    |         - `ibad` dropped here while still borrowed
+   |
+note: requirement that the value outlives `'1` introduced here
+  --> src/scope.rs
+   |
+   |         T: UserData + 'env,
+   |                       ^^^^

tests/conversion.rs

@@ -267,7 +267,7 @@ fn test_registry_value_into_lua() -> Result<()> {
     let r = lua.create_registry_value(&s)?;
     let value1 = lua.pack(&r)?;
     let value2 = lua.pack(r)?;
-    assert_eq!(value1.as_str().as_deref(), Some("hello, world"));
+    assert_eq!(value1.to_string()?, "hello, world");
     assert_eq!(value1.to_pointer(), value2.to_pointer());
 
     // Push into stack
@@ -560,11 +560,11 @@ fn test_osstring_into_from_lua() -> Result<()> {
 
     let v = lua.pack(s.as_os_str())?;
     assert!(v.is_string());
-    assert_eq!(v.as_str().unwrap(), "hello, world");
+    assert_eq!(v.as_string().unwrap(), "hello, world");
 
     let v = lua.pack(s)?;
     assert!(v.is_string());
-    assert_eq!(v.as_str().unwrap(), "hello, world");
+    assert_eq!(v.as_string().unwrap(), "hello, world");
 
     let s = lua.create_string("hello, world")?;
     let bstr = lua.unpack::<OsString>(Value::String(s))?;
@@ -588,11 +588,11 @@ fn test_pathbuf_into_from_lua() -> Result<()> {
 
     let v = lua.pack(pb.as_path())?;
     assert!(v.is_string());
-    assert_eq!(v.as_str().unwrap(), pb_str);
+    assert_eq!(v.to_string().unwrap(), pb_str);
 
     let v = lua.pack(pb.clone())?;
     assert!(v.is_string());
-    assert_eq!(v.as_str().unwrap(), pb_str);
+    assert_eq!(v.to_string().unwrap(), pb_str);
 
     let s = lua.create_string(pb_str)?;
     let bstr = lua.unpack::<PathBuf>(Value::String(s))?;
@@ -724,7 +724,7 @@ fn test_char_into_lua() -> Result<()> {
 
     let v = '🦀';
     let v2 = v.into_lua(&lua)?;
-    assert_eq!(Some(v.to_string()), v2.as_string_lossy());
+    assert_eq!(*v2.as_string().unwrap(), v.to_string());
 
     Ok(())
 }

tests/function.rs

@@ -194,6 +194,25 @@ fn test_function_info() -> Result<()> {
     assert_eq!(print_info.what, "C");
     assert_eq!(print_info.line_defined, None);
 
+    // Function with upvalues and params
+    #[cfg(not(any(feature = "lua51", feature = "luajit")))]
+    {
+        let func_with_upvalues = lua
+            .load(
+                r#"
+        local x, y = ...
+        return function(a, ...)
+            return a*x + y
+        end
+    "#,
+            )
+            .call::<Function>((10, 20))?;
+        let func_with_upvalues_info = func_with_upvalues.info();
+        assert_eq!(func_with_upvalues_info.num_upvalues, 2);
+        assert_eq!(func_with_upvalues_info.num_params, 1);
+        assert_eq!(func_with_upvalues_info.is_vararg, true);
+    }
+
     Ok(())
 }
 
@@ -306,7 +325,7 @@ fn test_function_deep_clone() -> Result<()> {
 
     lua.globals().set("a", 1)?;
     let func1 = lua.load("a += 1; return a").into_function()?;
-    let func2 = func1.deep_clone();
+    let func2 = func1.deep_clone()?;
 
     assert_ne!(func1.to_pointer(), func2.to_pointer());
     assert_eq!(func1.call::<i32>(())?, 2);
@@ -314,7 +333,7 @@ fn test_function_deep_clone() -> Result<()> {
 
     // Check that for Rust functions deep_clone is just a clone
     let rust_func = lua.create_function(|_, ()| Ok(42))?;
-    let rust_func2 = rust_func.deep_clone();
+    let rust_func2 = rust_func.deep_clone()?;
     assert_eq!(rust_func.to_pointer(), rust_func2.to_pointer());
 
     Ok(())

tests/hooks.rs

@@ -24,7 +24,7 @@ fn test_line_counts() -> Result<()> {
     let lua = Lua::new();
     lua.set_hook(HookTriggers::EVERY_LINE, move |_lua, debug| {
         assert_eq!(debug.event(), DebugEvent::Line);
-        hook_output.lock().unwrap().push(debug.curr_line());
+        hook_output.lock().unwrap().push(debug.current_line().unwrap());
         Ok(VmState::Continue)
     })?;
     lua.load(
@@ -240,7 +240,7 @@ fn test_hook_threads() -> Result<()> {
     let hook_output = output.clone();
     co.set_hook(HookTriggers::EVERY_LINE, move |_lua, debug| {
         assert_eq!(debug.event(), DebugEvent::Line);
-        hook_output.lock().unwrap().push(debug.curr_line());
+        hook_output.lock().unwrap().push(debug.current_line().unwrap());
         Ok(VmState::Continue)
     })?;
 
@@ -274,7 +274,7 @@ fn test_hook_yield() -> Result<()> {
 
     co.set_hook(HookTriggers::EVERY_LINE, move |_lua, _debug| Ok(VmState::Yield))?;
 
-    #[cfg(any(feature = "lua54", feature = "lua53"))]
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53"))]
     {
         assert!(co.resume::<()>(()).is_ok());
         assert!(co.resume::<()>(()).is_ok());

tests/luau.rs

@@ -3,7 +3,6 @@
 use std::cell::Cell;
 use std::fmt::Debug;
 use std::os::raw::c_void;
-use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::sync::atomic::{AtomicBool, AtomicPtr, AtomicU64, Ordering};
 use std::sync::Arc;
 
@@ -120,11 +119,13 @@ fn test_vector_metatable() -> Result<()> {
     "#,
         )
         .eval::<Table>()?;
-    vector_mt.set_metatable(Some(vector_mt.clone()));
+    vector_mt.set_metatable(Some(vector_mt.clone()))?;
     lua.set_type_metatable::<Vector>(Some(vector_mt.clone()));
     lua.globals().set("Vector3", vector_mt)?;
 
-    let compiler = Compiler::new().set_vector_lib("Vector3").set_vector_ctor("new");
+    let compiler = Compiler::new()
+        .set_vector_ctor("Vector3.new")
+        .set_vector_type("Vector3");
 
     // Test vector methods (fastcall)
     lua.load(
@@ -167,9 +168,9 @@ fn test_readonly_table() -> Result<()> {
     check_readonly_error(t.raw_pop::<Value>());
 
     // Special case
-    match catch_unwind(AssertUnwindSafe(|| t.set_metatable(None))) {
-        Ok(_) => panic!("expected panic, got nothing"),
-        Err(_) => {}
+    match t.set_metatable(None) {
+        Err(Error::RuntimeError(e)) if e.contains("attempt to modify a readonly table") => {}
+        r => panic!("expected RuntimeError(...) with a specific message, got {r:?}"),
     }
 
     Ok(())
@@ -196,6 +197,14 @@ fn test_sandbox() -> Result<()> {
     co.sandbox()?;
     assert_eq!(co.resume::<Option<i32>>(())?, Some(123));
 
+    // collectgarbage should be restricted in sandboxed mode
+    let collectgarbage = lua.globals().get::<Function>("collectgarbage")?;
+    for arg in ["collect", "stop", "restart", "step", "isrunning"] {
+        let err = collectgarbage.call::<()>(arg).err().unwrap().to_string();
+        assert!(err.contains("collectgarbage called with invalid option"));
+    }
+    assert!(collectgarbage.call::<u64>("count").unwrap() > 0);
+
     lua.sandbox(false)?;
 
     // Previously set variable `global` should be cleared now
@@ -205,6 +214,11 @@ fn test_sandbox() -> Result<()> {
     let table = lua.globals().get::<Table>("table")?;
     table.set("test", "test")?;
 
+    // collectgarbage should work now
+    for arg in ["collect", "stop", "restart", "count", "step", "isrunning"] {
+        collectgarbage.call::<()>(arg).unwrap();
+    }
+
     Ok(())
 }
 
@@ -316,6 +330,15 @@ fn test_interrupts() -> Result<()> {
     assert_eq!(yield_count.load(Ordering::Relaxed), 7);
     assert_eq!(co.status(), ThreadStatus::Finished);
 
+    // Test no yielding at non-yieldable points
+    yield_count.store(0, Ordering::Relaxed);
+    let co = lua.create_thread(lua.create_function(|lua, arg: Value| {
+        (lua.load("return (function(x) return x end)(...)")).call::<Value>(arg)
+    })?)?;
+    let res = co.resume::<String>("abc")?;
+    assert_eq!(res, "abc".to_string());
+    assert_eq!(yield_count.load(Ordering::Relaxed), 3);
+
     //
     // Test errors in interrupts
     //
@@ -425,7 +448,7 @@ fn test_loadstring() -> Result<()> {
     assert_eq!(f.call::<i32>(())?, 123);
 
     let err = lua
-        .load(r#"loadstring("retur 123", "chunk")"#)
+        .load(r#"loadstring("retur 123", "chunk")"#) // typos:ignore
         .exec()
         .err()
         .unwrap();
@@ -447,5 +470,70 @@ fn test_typeof_error() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_memory_category() -> Result<()> {
+    let lua = Lua::new();
+
+    lua.set_memory_category("main").unwrap();
+
+    // Invalid category names should be rejected
+    let err = lua.set_memory_category("invalid$");
+    assert!(err.is_err());
+
+    for i in 0..254 {
+        let name = format!("category_{}", i);
+        lua.set_memory_category(&name).unwrap();
+    }
+    // 255th category should fail
+    let err = lua.set_memory_category("category_254");
+    assert!(err.is_err());
+
+    Ok(())
+}
+
+#[test]
+fn test_heap_dump() -> Result<()> {
+    let lua = Lua::new();
+
+    // Assign a new memory category and create few objects
+    lua.set_memory_category("test_category")?;
+    let _t = lua.create_table()?;
+    let _ud = lua.create_any_userdata("hello, world")?;
+
+    let dump = lua.heap_dump()?;
+
+    assert!(dump.size() > 0);
+    let size_by_category = dump.size_by_category();
+    assert_eq!(size_by_category.len(), 2);
+    assert!(size_by_category.contains_key("test_category"));
+    assert!(size_by_category["main"] < dump.size());
+
+    // Check size by type within the category
+    let size_by_type = dump.size_by_type(Some("test_category"));
+    assert!(!size_by_type.is_empty());
+    assert!(size_by_type.contains_key("table"));
+    assert!(size_by_type.contains_key("userdata"));
+    // Try non-existent category
+    let size_by_type2 = dump.size_by_type(Some("non_existent_category"));
+    assert!(size_by_type2.is_empty());
+    // Remove category filter
+    let size_by_type_all = dump.size_by_type(None);
+    assert!(size_by_type.len() < size_by_type_all.len());
+
+    // Check size by userdata type within the category
+    let size_by_udtype = dump.size_by_userdata(Some("test_category"));
+    assert_eq!(size_by_udtype.len(), 1);
+    assert!(size_by_udtype.contains_key("&str"));
+    assert_eq!(size_by_udtype["&str"].0, 1);
+    // Try non-existent category
+    let size_by_udtype2 = dump.size_by_userdata(Some("non_existent_category"));
+    assert!(size_by_udtype2.is_empty());
+    // Remove category filter
+    let size_by_udtype_all = dump.size_by_userdata(None);
+    assert!(size_by_udtype.len() < size_by_udtype_all.len());
+
+    Ok(())
+}
+
 #[path = "luau/require.rs"]
 mod require;

tests/luau/require.rs

@@ -1,7 +1,7 @@
 use std::io::Result as IoResult;
 use std::result::Result as StdResult;
 
-use mlua::{Error, IntoLua, Lua, MultiValue, NavigateError, Require, Result, TextRequirer, Value};
+use mlua::{Error, FromLua, IntoLua, Lua, MultiValue, NavigateError, Require, Result, TextRequirer, Value};
 
 fn run_require(lua: &Lua, path: impl IntoLua) -> Result<Value> {
     lua.load(r#"return require(...)"#).call(path)
@@ -11,9 +11,14 @@ fn run_require_pcall(lua: &Lua, path: impl IntoLua) -> Result<MultiValue> {
     lua.load(r#"return pcall(require, ...)"#).call(path)
 }
 
+#[track_caller]
+fn get_value<V: FromLua>(value: &Value, key: impl IntoLua) -> V {
+    value.as_table().unwrap().get(key).unwrap()
+}
+
 #[track_caller]
 fn get_str(value: &Value, key: impl IntoLua) -> String {
-    value.as_table().unwrap().get::<String>(key).unwrap()
+    get_value(value, key)
 }
 
 #[test]
@@ -47,6 +52,16 @@ fn test_require_errors() {
     assert!(res.is_err());
     assert!((res.unwrap_err().to_string()).contains("require is not supported in this context"));
 
+    // RequireAliasThatDoesNotExist
+    let res = run_require(&lua, "@this.alias.does.not.exist");
+    assert!(res.is_err());
+    assert!((res.unwrap_err().to_string()).contains("@this.alias.does.not.exist is not a valid alias"));
+
+    // IllegalAlias
+    let res = run_require(&lua, "@");
+    assert!(res.is_err());
+    assert!((res.unwrap_err().to_string()).contains("@ is not a valid alias"));
+
     // Test throwing mlua::Error
     struct MyRequire(TextRequirer);
 
@@ -105,94 +120,133 @@ fn test_require_without_config() {
     let lua = Lua::new();
 
     // RequireSimpleRelativePath
-    let res = run_require(&lua, "./require/without_config/dependency").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/dependency").unwrap();
     assert_eq!("result from dependency", get_str(&res, 1));
 
     // RequireSimpleRelativePathWithinPcall
-    let res = run_require_pcall(&lua, "./require/without_config/dependency").unwrap();
+    let res = run_require_pcall(&lua, "./tests/luau/require/without_config/dependency").unwrap();
     assert!(res[0].as_boolean().unwrap());
     assert_eq!("result from dependency", get_str(&res[1], 1));
 
     // RequireRelativeToRequiringFile
-    let res = run_require(&lua, "./require/without_config/module").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/module").unwrap();
     assert_eq!("result from dependency", get_str(&res, 1));
     assert_eq!("required into module", get_str(&res, 2));
 
     // RequireLua
-    let res = run_require(&lua, "./require/without_config/lua_dependency").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/lua_dependency").unwrap();
     assert_eq!("result from lua_dependency", get_str(&res, 1));
 
     // RequireInitLuau
-    let res = run_require(&lua, "./require/without_config/luau").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/luau").unwrap();
     assert_eq!("result from init.luau", get_str(&res, 1));
 
     // RequireInitLua
-    let res = run_require(&lua, "./require/without_config/lua").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/lua").unwrap();
     assert_eq!("result from init.lua", get_str(&res, 1));
 
     // RequireSubmoduleUsingSelfIndirectly
-    let res = run_require(&lua, "./require/without_config/nested_module_requirer").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/nested_module_requirer").unwrap();
     assert_eq!("result from submodule", get_str(&res, 1));
 
     // RequireSubmoduleUsingSelfDirectly
-    let res = run_require(&lua, "./require/without_config/nested").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/nested").unwrap();
     assert_eq!("result from submodule", get_str(&res, 1));
 
     // CannotRequireInitLuauDirectly
-    let res = run_require(&lua, "./require/without_config/nested/init");
+    let res = run_require(&lua, "./tests/luau/require/without_config/nested/init");
     assert!(res.is_err());
     assert!((res.unwrap_err().to_string()).contains("could not resolve child component \"init\""));
 
     // RequireNestedInits
-    let res = run_require(&lua, "./require/without_config/nested_inits_requirer").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/nested_inits_requirer").unwrap();
     assert_eq!("result from nested_inits/init", get_str(&res, 1));
     assert_eq!("required into module", get_str(&res, 2));
 
     // RequireWithFileAmbiguity
-    let res = run_require(&lua, "./require/without_config/ambiguous_file_requirer");
+    let res = run_require(
+        &lua,
+        "./tests/luau/require/without_config/ambiguous_file_requirer",
+    );
     assert!(res.is_err());
     assert!((res.unwrap_err().to_string())
         .contains("could not resolve child component \"dependency\" (ambiguous)"));
 
     // RequireWithDirectoryAmbiguity
-    let res = run_require(&lua, "./require/without_config/ambiguous_directory_requirer");
+    let res = run_require(
+        &lua,
+        "./tests/luau/require/without_config/ambiguous_directory_requirer",
+    );
     assert!(res.is_err());
     assert!((res.unwrap_err().to_string())
         .contains("could not resolve child component \"dependency\" (ambiguous)"));
 
     // CheckCachedResult
-    let res = run_require(&lua, "./require/without_config/validate_cache").unwrap();
+    let res = run_require(&lua, "./tests/luau/require/without_config/validate_cache").unwrap();
     assert!(res.is_table());
 }
 
+fn test_require_with_config_inner(r#type: &str) {
+    let lua = Lua::new();
+
+    let base_path = format!("./tests/luau/require/{type}");
+
+    // RequirePathWithAlias
+    let res = run_require(&lua, format!("{base_path}/src/alias_requirer")).unwrap();
+    assert_eq!("result from dependency", get_str(&res, 1));
+
+    // RequirePathWithAlias (case-insensitive)
+    let res2 = run_require(&lua, format!("{base_path}/src/alias_requirer_uc")).unwrap();
+    assert_eq!("result from dependency", get_str(&res2, 1));
+    assert_eq!(res.to_pointer(), res2.to_pointer());
+
+    // RequirePathWithParentAlias
+    let res = run_require(&lua, format!("{base_path}/src/parent_alias_requirer")).unwrap();
+    assert_eq!("result from other_dependency", get_str(&res, 1));
+
+    // RequirePathWithAliasPointingToDirectory
+    let res = run_require(&lua, format!("{base_path}/src/directory_alias_requirer")).unwrap();
+    assert_eq!("result from subdirectory_dependency", get_str(&res, 1));
+
+    // RequireChainedAliasesSuccess
+    let res = run_require(
+        &lua,
+        format!("{base_path}/chained_aliases/subdirectory/successful_requirer"),
+    )
+    .unwrap();
+    assert_eq!("result from inner_dependency", get_str(&get_value(&res, 1), 1));
+    assert_eq!("result from outer_dependency", get_str(&get_value(&res, 2), 1));
+
+    // RequireChainedAliasesFailureCyclic
+    let res = run_require(
+        &lua,
+        format!("{base_path}/chained_aliases/subdirectory/failing_requirer_cyclic"),
+    );
+    assert!(res.is_err());
+    let err_msg = "error requiring module \"@cyclicentry\": detected alias cycle (@cyclic1 -> @cyclic2 -> @cyclic3 -> @cyclic1)";
+    assert!(res.unwrap_err().to_string().contains(err_msg));
+
+    // RequireChainedAliasesFailureMissing
+    let res = run_require(
+        &lua,
+        format!("{base_path}/chained_aliases/subdirectory/failing_requirer_missing"),
+    );
+    assert!(res.is_err());
+    let err_msg = "error requiring module \"@brokenchain\": @missing is not a valid alias";
+    assert!(res.unwrap_err().to_string().contains(err_msg));
+}
+
 #[test]
 fn test_require_with_config() {
-    let lua = Lua::new();
-
-    // RequirePathWithAlias
-    let res = run_require(&lua, "./require/with_config/src/alias_requirer").unwrap();
-    assert_eq!("result from dependency", get_str(&res, 1));
-
-    // RequirePathWithParentAlias
-    let res = run_require(&lua, "./require/with_config/src/parent_alias_requirer").unwrap();
-    assert_eq!("result from other_dependency", get_str(&res, 1));
-
-    // RequirePathWithAliasPointingToDirectory
-    let res = run_require(&lua, "./require/with_config/src/directory_alias_requirer").unwrap();
-    assert_eq!("result from subdirectory_dependency", get_str(&res, 1));
-
-    // RequireAliasThatDoesNotExist
-    let res = run_require(&lua, "@this.alias.does.not.exist");
-    assert!(res.is_err());
-    assert!((res.unwrap_err().to_string()).contains("@this.alias.does.not.exist is not a valid alias"));
-
-    // IllegalAlias
-    let res = run_require(&lua, "@");
-    assert!(res.is_err());
-    assert!((res.unwrap_err().to_string()).contains("@ is not a valid alias"));
+    test_require_with_config_inner("with_config");
 }
 
-#[cfg(feature = "async")]
+#[test]
+fn test_require_with_config_luau() {
+    test_require_with_config_inner("with_config_luau");
+}
+
+#[cfg(all(feature = "async", not(windows)))]
 #[tokio::test]
 async fn test_async_require() -> Result<()> {
     let lua = Lua::new();
@@ -215,14 +269,19 @@ async fn test_async_require() -> Result<()> {
             Ok(())
         })?,
     )?;
+    lua.globals().set("tmp_dir", temp_dir.path().to_str().unwrap())?;
+    lua.globals().set(
+        "curr_dir_components",
+        std::env::current_dir().unwrap().components().count(),
+    )?;
 
     lua.load(
         r#"
-        local result = require("./async_chunk")
+        local path_to_root = string.rep("/..", curr_dir_components - 1)
+        local result = require(`.{path_to_root}{tmp_dir}/async_chunk`)
         assert(result == "result_after_async_sleep")
         "#,
     )
-    .set_name(format!("@{}", temp_dir.path().join("require.rs").display()))
     .exec_async()
     .await
 }

tests/luau/require/with_config/chained_aliases/.luaurc

@@ -0,0 +1,9 @@
+{
+    "aliases":{
+        "outer": "./",
+        "cyclicentry": "@cyclic1",
+        "cyclic1": "@cyclic2",
+        "cyclic2": "@cyclic3",
+        "cyclic3": "@cyclic1"
+    }
+}

tests/luau/require/with_config/chained_aliases/outer_dependency.luau

@@ -0,0 +1 @@
+return {"result from outer_dependency"}

tests/luau/require/with_config/chained_aliases/subdirectory/.luaurc

@@ -0,0 +1,10 @@
+{
+    "aliases":{
+        "passthroughinner": "./inner_dependency",
+        "passthroughouter": "@outer",
+        "dep": "@passthroughinner",
+        "outerdep": "@outer/outer_dependency",
+        "outerdir": "@passthroughouter",
+        "brokenchain": "@missing"
+    }
+}

tests/luau/require/with_config/chained_aliases/subdirectory/failing_requirer_cyclic.luau

@@ -0,0 +1 @@
+return require("@cyclicentry")

tests/luau/require/with_config/chained_aliases/subdirectory/failing_requirer_missing.luau

@@ -0,0 +1 @@
+return require("@brokenchain")

tests/luau/require/with_config/chained_aliases/subdirectory/inner_dependency.luau

@@ -0,0 +1 @@
+return {"result from inner_dependency"}

tests/luau/require/with_config/chained_aliases/subdirectory/successful_requirer.luau

@@ -0,0 +1,7 @@
+local result = {}
+
+table.insert(result, require("@dep"))
+table.insert(result, require("@outerdep"))
+table.insert(result, require("@outerdir/outer_dependency"))
+
+return result

tests/luau/require/with_config/src/alias_requirer_uc.luau

@@ -0,0 +1 @@
+return require("@DeP")

tests/luau/require/with_config_luau/.config.luau

@@ -0,0 +1,8 @@
+return {
+    luau = {
+        aliases = {
+            dep = "./this_should_be_overwritten_by_child_luaurc",
+            otherdep = "./src/other_dependency"
+        }
+    }
+}

tests/luau/require/with_config_luau/chained_aliases/.config.luau

@@ -0,0 +1,11 @@
+return {
+    luau = {
+        aliases = {
+            outer = "./",
+            cyclicentry = "@cyclic1",
+            cyclic1 = "@cyclic2",
+            cyclic2 = "@cyclic3",
+            cyclic3 = "@cyclic1"
+        }
+    }
+}