Update CHANGELOG

v0.12.0-rc.1
Update compile tests messages
2026-06-08 16:05:43 +00:00 · 2026-04-22 00:06:11 +01:00 · 2026-04-20 00:24:58 +01:00 · 2026-04-20 00:19:56 +01:00 · 2026-04-20 00:16:34 +01:00 · 2026-04-20 00:05:57 +01:00
81 changed files with 2167 additions and 1510 deletions
@@ -0,0 +1,68 @@
+name: Documentation (main)
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# Allow only one concurrent deployment
+concurrency:
+  group: pages
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: Build Documentation
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@main
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Build documentation
+        env:
+          RUSTDOCFLAGS: "--cfg docsrs"
+        run: |
+          cargo +nightly doc --no-deps \
+            --features "lua55,vendored,async,send,serde,macros,anyhow,userdata-wrappers"
+
+      - name: Create index redirect
+        run: |
+          echo '<!DOCTYPE html>
+          <html>
+            <head>
+              <meta charset="utf-8">
+              <title>Redirecting to mlua documentation</title>
+              <meta http-equiv="refresh" content="0; URL=mlua/index.html">
+              <link rel="canonical" href="mlua/index.html">
+            </head>
+            <body>
+              <p>Redirecting to <a href="mlua/index.html">mlua documentation</a>...</p>
+            </body>
+          </html>' > target/doc/index.html
+
+      - name: Setup Pages
+        uses: actions/configure-pages@v5
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v4
+        with:
+          path: target/doc
+
+  deploy:
+    name: Deploy to GitHub Pages
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4
@@ -1,3 +1,22 @@
+## v0.12.0-rc.1 (Apr 21, 2026)
+
+- Rust 2024 edition
+- Removed `Error::ToLuaConversionError` variant as it was unused (and not practically useful)
+- New modules to group data types: `chunk`, `debug`, `error`, `function`, `table`, `string`, `state`, `thread`, `userdata`, `luau`
+- Support `__todebugstring` metamethod for pretty formatting userdata value (for debugging)
+- New `MaybeSync` trait that is required for userdata types
+- Removed lifetime from `BorrowedStr` and `BorrowedBytes`
+- New `Thread` methods: `is_resumable`, `is_running`, `is_finished`, `is_error`
+- Added `Thread::state` to get raw Lua state pointer
+- Luau `TextRequirer` is renamed to `FsRequirer`
+- GC interface refactor: `Lua::gc_inc/Lua::gc_gen` is replaced with `gc_set_mode`
+- Added `GcIncParams` and `GcGenParams` for GC tuning
+- New `UserDataMethods::add_method_once` and `UserDataMethods::add_async_method_once`
+- Initial Luau integer64 type support
+- Changed interface of `Function::wrap/wrap_mut/wrap_async` to support any Error type
+- Changed `AnyUserData::type_name` to return `LuaString` instead
+- Added `UserDataOwned<T>` wrapper to take ownership of userdata `T` and implements `FromLua`
+
 ## v0.11.6 (Jan 27, 2026)

 - Added Lua 5.5 support (`lua55` feature flag)
@@ -1,9 +1,9 @@
 [package]
 name = "mlua"
-version = "0.11.6" # remember to update mlua_derive
+version = "0.12.0-rc.1" # remember to update mlua_derive
 authors = ["Aleksandr Orlenko <zxteam@pm.me>", "kyren <catherine@kyju.org>"]
-rust-version = "1.85.0"
-edition = "2021"
+rust-version = "1.88"
+edition = "2024"
 repository = "https://github.com/mlua-rs/mlua"
 documentation = "https://docs.rs/mlua"
 readme = "README.md"
@@ -61,10 +61,9 @@ erased-serde = { version = "0.4", optional = true }
 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 = "0.10.0", path = "mlua-sys" }
+ffi = { package = "mlua-sys", version = "0.11.0-rc.1", path = "mlua-sys" }

 [dev-dependencies]
 trybuild = "1.0"
@@ -78,10 +77,10 @@ static_assertions = "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"] }
+reqwest = { version = "0.13", features = ["json"] }
 tempfile = "3"
-criterion = { version = "0.7", features = ["async_tokio"] }
-rustyline = "17.0"
+criterion = { version = "0.8", features = ["async_tokio"] }
+rustyline = "18.0"
 tokio = { version = "1.0", features = ["full"] }

 [lints.rust]
@@ -17,6 +17,8 @@
 [Benchmarks]: https://github.com/khvzak/script-bench-rs
 [FAQ]: FAQ.md

+## The main branch is the development version of `mlua`. Please see the [v0.11](https://github.com/mlua-rs/mlua/tree/v0.11) branch for the stable versions of `mlua`.
+
 `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.

@@ -125,7 +127,7 @@ my_project $ LUA_LIB=$HOME/tmp/lua-5.2.4/src LUA_LIB_NAME=lua LUA_LINK=static ca
 Just enable the `vendored` feature and cargo will automatically build and link the specified Lua/LuaJIT version. This is the easiest way to get started with `mlua`.

 ### Standalone mode
-In standalone mode, `mlua` allows adding scripting support to your application with a gently configured Lua runtime to ensure safety and soundness.
+In standalone mode, `mlua` allows adding scripting support to your application with a properly configured Lua runtime to ensure safety and soundness.

 Add to `Cargo.toml`:

@@ -1,7 +1,7 @@
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Duration;

-use criterion::{criterion_group, criterion_main, BatchSize, Criterion};
+use criterion::{BatchSize, Criterion, criterion_group, criterion_main};
 use tokio::runtime::Runtime;
 use tokio::task;

@@ -1,6 +1,6 @@
 use std::time::Duration;

-use criterion::{criterion_group, criterion_main, BatchSize, Criterion};
+use criterion::{BatchSize, Criterion, criterion_group, criterion_main};

 use mlua::prelude::*;

@@ -1,6 +1,6 @@
 ## mlua v0.10 release notes

-The v0.10 version of mlua has goal to improve the user experience while keeping the same performance and safety guarantees.
+The v0.10 version of mlua has a goal to improve the user experience while keeping the same performance and safety guarantees.
 This document highlights the most notable features. For a full list of changes, see the [CHANGELOG].

 [CHANGELOG]: https://github.com/mlua-rs/mlua/blob/main/CHANGELOG.md
@@ -40,7 +40,7 @@ assert_eq!(lua.globals().get::<i32>("i")?, 20);

 Under the hood, to synchronize access to the Lua state, mlua uses [`ReentrantMutex`] which can be recursively locked by a single thread. Only one thread can execute Lua code at a time, but it's possible to share Lua values between threads.

-This has some performance penalties (about 10-20%) compared to the lock free mode. This flag is disabled by default and does not supported in module mode.
+This has some performance penalties (about 10-20%) compared to the lock free mode. This flag is disabled by default and is not supported in module mode.

 [`ReentrantMutex`]: https://docs.rs/parking_lot/latest/parking_lot/type.ReentrantMutex.html

@@ -144,7 +144,7 @@ The following `Scope` methods were changed:
 Instead, scope has comprehensive support for borrowed userdata: `create_any_userdata_ref`, `create_any_userdata_ref_mut`, `create_userdata_ref`, `create_userdata_ref_mut`.

 `UserDataRef` and `UserDataRefMut` are no longer acceptable for scoped userdata access as they require owned underlying data.
-In mlua v0.9 this can cause read-after-free bug in some edge cases.
+In mlua v0.9 this could cause a read-after-free bug in some edge cases.

 To temporarily borrow underlying data, the `AnyUserData::borrow_scoped` and `AnyUserData::borrow_mut_scoped` methods were introduced:

@@ -152,9 +152,9 @@ It will automatically trigger JIT compilation for new Lua chunks. To disable it,

 #### 1. Better error reporting

-When calling a Rust function from Lua and passing wrong arguments, previous mlua versions reported a error message without any context or reference to the particular argument.
+When calling a Rust function from Lua and passing wrong arguments, previous mlua versions reported an error message without any context or reference to the particular argument.

-In v0.9 it reports a error message with the argument index and expected type:
+In v0.9 it reports an error message with the argument index and expected type:

 ```rust
 let func = lua.create_function(|_, _a: i32| Ok(()))?;
@@ -327,7 +327,7 @@ Under the hood a new function `luaopen_alt_module` will be created for the Lua m

 - `skip_memory_check` - skip memory allocation checks for some operations.

-In module mode, mlua runs in unknown environment and cannot say are there any memory limits or not. As result, some operations that require memory allocation runs in
+In module mode, mlua runs in an unknown environment and cannot tell whether there are any memory limits or not. As a result, some operations that require memory allocation run in
 protected mode. Setting this attribute will improve performance of such operations with risk of having uncaught exceptions and memory leaks.

 #### Improved Windows target
@@ -5,7 +5,7 @@ use hyper::body::Incoming;
 use hyper_util::client::legacy::Client as HyperClient;
 use hyper_util::rt::TokioExecutor;

-use mlua::{chunk, ExternalResult, Lua, Result, UserData, UserDataMethods};
+use mlua::{ExternalResult, Lua, Result, UserData, UserDataMethods, chunk};

 struct BodyReader(Incoming);

@@ -1,4 +1,4 @@
-use mlua::{chunk, ExternalResult, Lua, LuaSerdeExt, Result, Value};
+use mlua::{ExternalResult, Lua, LuaSerdeExt, Result, Value, chunk};

 #[tokio::main(flavor = "current_thread")]
 async fn main() -> Result<()> {
@@ -11,7 +11,7 @@ use hyper::{Request, Response};
 use hyper_util::rt::TokioIo;
 use tokio::net::TcpListener;

-use mlua::{chunk, Error as LuaError, Function, Lua, String as LuaString, Table, UserData, UserDataMethods};
+use mlua::{Error as LuaError, Function, Lua, String as LuaString, Table, UserData, UserDataMethods, chunk};

 /// Wrapper around incoming request that implements UserData
 struct LuaRequest(SocketAddr, Request<Incoming>);
@@ -4,7 +4,7 @@ use std::net::SocketAddr;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};

-use mlua::{chunk, BString, Function, Lua, UserData, UserDataMethods};
+use mlua::{BString, Function, Lua, UserData, UserDataMethods, chunk};

 struct LuaTcpStream(TcpStream);

@@ -1,7 +1,7 @@
 use std::f32;
 use std::iter::FromIterator;

-use mlua::{chunk, FromLua, Function, Lua, MetaMethod, Result, UserData, UserDataMethods, Value, Variadic};
+use mlua::{FromLua, Function, Lua, MetaMethod, Result, UserData, UserDataMethods, Value, Variadic, chunk};

 fn main() -> Result<()> {
    // You can create a new Lua state with `Lua::new()`. This loads the default Lua std library
@@ -1,4 +1,4 @@
-use mlua::{chunk, Lua, MetaMethod, Result, UserData};
+use mlua::{Lua, MetaMethod, Result, UserData, chunk};

 #[derive(Default)]
 struct Rectangle {
@@ -1,8 +1,8 @@
 [package]
 name = "mlua-sys"
-version = "0.10.0"
+version = "0.11.0-rc.1"
 authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
-rust-version = "1.85"
+rust-version = "1.88"
 edition = "2024"
 repository = "https://github.com/mlua-rs/mlua"
 documentation = "https://docs.rs/mlua-sys"
@@ -41,9 +41,9 @@ libc = "0.2"
 cc = "1.0"
 cfg-if = "1.0"
 pkg-config = "0.3.17"
-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 = "0.18.0", optional = true }
+lua-src = { version = ">= 550.1.0, < 550.2.0", optional = true }
+luajit-src = { version = ">= 210.7.0, < 210.8.0", optional = true }
+luau0-src = { version = "0.20.0", optional = true }

 [lints.rust]
 unexpected_cfgs = { level = "allow", check-cfg = ['cfg(raw_dylib)'] }
@@ -38,8 +38,10 @@ unsafe extern "C-unwind" {

    #[link_name = "luaL_checkinteger"]
    pub fn luaL_checkinteger_(L: *mut lua_State, narg: c_int) -> c_int;
+    pub fn luaL_checkinteger64(L: *mut lua_State, narg: c_int) -> i64;
    #[link_name = "luaL_optinteger"]
    pub fn luaL_optinteger_(L: *mut lua_State, narg: c_int, def: c_int) -> c_int;
+    pub fn luaL_optinteger64(L: *mut lua_State, narg: c_int, def: i64) -> i64;
    pub fn luaL_checkunsigned(L: *mut lua_State, narg: c_int) -> lua_Unsigned;
    pub fn luaL_optunsigned(L: *mut lua_State, narg: c_int, def: lua_Unsigned) -> lua_Unsigned;

@@ -65,14 +65,15 @@ pub const LUA_TBOOLEAN: c_int = 1;

 pub const LUA_TLIGHTUSERDATA: c_int = 2;
 pub const LUA_TNUMBER: c_int = 3;
-pub const LUA_TVECTOR: c_int = 4;
+pub const LUA_TINTEGER: c_int = 4;
+pub const LUA_TVECTOR: c_int = 5;

-pub const LUA_TSTRING: c_int = 5;
-pub const LUA_TTABLE: c_int = 6;
-pub const LUA_TFUNCTION: c_int = 7;
-pub const LUA_TUSERDATA: c_int = 8;
-pub const LUA_TTHREAD: c_int = 9;
-pub const LUA_TBUFFER: c_int = 10;
+pub const LUA_TSTRING: c_int = 6;
+pub const LUA_TTABLE: c_int = 7;
+pub const LUA_TFUNCTION: c_int = 8;
+pub const LUA_TUSERDATA: c_int = 9;
+pub const LUA_TTHREAD: c_int = 10;
+pub const LUA_TBUFFER: c_int = 11;

 /// Guaranteed number of Lua stack slots available to a C function.
 pub const LUA_MINSTACK: c_int = 20;
@@ -153,6 +154,7 @@ unsafe extern "C-unwind" {
    pub fn lua_tounsignedx(L: *mut lua_State, idx: c_int, isnum: *mut c_int) -> lua_Unsigned;
    pub fn lua_tovector(L: *mut lua_State, idx: c_int) -> *const c_float;
    pub fn lua_toboolean(L: *mut lua_State, idx: c_int) -> c_int;
+    pub fn lua_tointeger64(L: *mut lua_State, idx: c_int, isinteger: *mut c_int) -> i64;
    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(
@@ -182,6 +184,7 @@ unsafe extern "C-unwind" {
    pub fn lua_pushnumber(L: *mut lua_State, n: lua_Number);
    #[link_name = "lua_pushinteger"]
    pub fn lua_pushinteger_(L: *mut lua_State, n: c_int);
+    pub fn lua_pushinteger64(L: *mut lua_State, n: i64);
    pub fn lua_pushunsigned(L: *mut lua_State, n: lua_Unsigned);
    #[cfg(not(feature = "luau-vector4"))]
    pub fn lua_pushvector(L: *mut lua_State, x: c_float, y: c_float, z: c_float);
@@ -412,6 +415,11 @@ 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_isinteger64(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TINTEGER) as c_int
+}
+
 #[inline(always)]
 pub unsafe fn lua_isvector(L: *mut lua_State, n: c_int) -> c_int {
    (lua_type(L, n) == LUA_TVECTOR) as c_int
@@ -501,6 +509,12 @@ pub type lua_Coverage = unsafe extern "C-unwind" fn(
    size: usize,
 );

+pub type lua_CounterFunction =
+    unsafe extern "C-unwind" fn(context: *mut c_void, function: *const c_char, linedefined: c_int);
+
+pub type lua_CounterValue =
+    unsafe extern "C-unwind" fn(context: *mut c_void, kind: c_int, line: c_int, hits: u64);
+
 unsafe extern "C-unwind" {
    pub fn lua_stackdepth(L: *mut lua_State) -> c_int;
    pub fn lua_getinfo(L: *mut lua_State, level: c_int, what: *const c_char, ar: *mut lua_Debug) -> c_int;
@@ -515,6 +529,14 @@ unsafe extern "C-unwind" {

    pub fn lua_getcoverage(L: *mut lua_State, funcindex: c_int, context: *mut c_void, callback: lua_Coverage);

+    pub fn lua_getcounters(
+        L: *mut lua_State,
+        funcindex: c_int,
+        context: *mut c_void,
+        functionvisit: lua_CounterFunction,
+        countervisit: lua_CounterValue,
+    );
+
    pub fn lua_debugtrace(L: *mut lua_State) -> *const c_char;
 }

@@ -551,8 +573,8 @@ pub struct lua_Callbacks {

    /// gets called when L is created (LP == parent) or destroyed (LP == NULL)
    pub userthread: Option<unsafe extern "C-unwind" fn(LP: *mut lua_State, L: *mut lua_State)>,
-    /// gets called when a string is created; returned atom can be retrieved via tostringatom
-    pub useratom: Option<unsafe extern "C-unwind" fn(s: *const c_char, l: usize) -> i16>,
+    /// gets called when a string is created to assign an atom id
+    pub useratom: Option<unsafe extern "C-unwind" fn(L: *mut lua_State, s: *const c_char, l: usize) -> i16>,

    /// gets called when BREAK instruction is encountered
    pub debugbreak: Option<unsafe extern "C-unwind" fn(L: *mut lua_State, ar: *mut lua_Debug)>,
@@ -80,6 +80,7 @@ unsafe extern "C" {
    pub fn luau_set_compile_constant_nil(cons: *mut lua_CompileConstant);
    pub fn luau_set_compile_constant_boolean(cons: *mut lua_CompileConstant, b: c_int);
    pub fn luau_set_compile_constant_number(cons: *mut lua_CompileConstant, n: f64);
+    pub fn luau_set_compile_constant_integer64(cons: *mut lua_CompileConstant, l: i64);
    pub fn luau_set_compile_constant_vector(cons: *mut lua_CompileConstant, x: f32, y: f32, z: f32, w: f32);
    pub fn luau_set_compile_constant_string(cons: *mut lua_CompileConstant, s: *const c_char, l: usize);
 }
@@ -14,6 +14,7 @@ pub const LUA_UTF8LIBNAME: *const c_char = cstr!("utf8");
 pub const LUA_MATHLIBNAME: *const c_char = cstr!("math");
 pub const LUA_DBLIBNAME: *const c_char = cstr!("debug");
 pub const LUA_VECLIBNAME: *const c_char = cstr!("vector");
+pub const LUA_INTLIBNAME: *const c_char = cstr!("integer");

 unsafe extern "C-unwind" {
    pub fn luaopen_base(L: *mut lua_State) -> c_int;
@@ -27,6 +28,7 @@ unsafe extern "C-unwind" {
    pub fn luaopen_math(L: *mut lua_State) -> c_int;
    pub fn luaopen_debug(L: *mut lua_State) -> c_int;
    pub fn luaopen_vector(L: *mut lua_State) -> c_int;
+    pub fn luaopen_integer(L: *mut lua_State) -> c_int;

    // open all builtin libraries
    pub fn luaL_openlibs(L: *mut lua_State);
@@ -59,7 +59,7 @@ impl Buffer {
    /// 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.
+    /// Buffer operations are infallible, none of the read/write functions will return an Err.
    pub fn cursor(self) -> impl io::Read + io::Write + io::Seek {
        BufferCursor(self, 0)
    }
@@ -97,7 +97,7 @@ 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 lua = self.0.0.lua.lock();
        let data = self.0.as_slice(&lua);
        if self.1 == data.len() {
            return Ok(0);
@@ -111,7 +111,7 @@ impl io::Read for BufferCursor {

 impl io::Write for BufferCursor {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        let lua = self.0 .0.lua.lock();
+        let lua = self.0.0.lua.lock();
        let data = self.0.as_slice_mut(&lua);
        if self.1 == data.len() {
            return Ok(0);
@@ -129,7 +129,7 @@ impl io::Write for BufferCursor {

 impl io::Seek for BufferCursor {
    fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
-        let lua = self.0 .0.lua.lock();
+        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,
@@ -1,10 +1,16 @@
+//! Lua chunk loading and execution.
+//!
+//! This module provides types for loading Lua source code or bytecode into a [`Chunk`],
+//! configuring how it is compiled and executed, and converting it into a callable [`Function`].
+//!
+//! Chunks can be loaded from strings, byte slices, or files via the [`AsChunk`] trait.
+
 use std::borrow::Cow;
 use std::collections::HashMap;
 use std::ffi::CString;
 use std::io::Result as IoResult;
 use std::panic::Location;
 use std::path::{Path, PathBuf};
-use std::string::String as StdString;

 use crate::error::{Error, Result};
 use crate::function::Function;
@@ -20,7 +26,7 @@ pub trait AsChunk {
    /// Returns optional chunk name
    ///
    /// See [`Chunk::set_name`] for possible name prefixes.
-    fn name(&self) -> Option<StdString> {
+    fn name(&self) -> Option<String> {
        None
    }

@@ -52,13 +58,13 @@ impl AsChunk for &str {
    }
 }

-impl AsChunk for StdString {
+impl AsChunk for String {
    fn source<'a>(&self) -> IoResult<Cow<'a, [u8]>> {
        Ok(Cow::Owned(self.clone().into_bytes()))
    }
 }

-impl AsChunk for &StdString {
+impl AsChunk for &String {
    fn source<'a>(&self) -> IoResult<Cow<'a, [u8]>>
    where
        Self: 'a,
@@ -92,7 +98,7 @@ impl AsChunk for &Vec<u8> {
 }

 impl AsChunk for &Path {
-    fn name(&self) -> Option<StdString> {
+    fn name(&self) -> Option<String> {
        Some(format!("@{}", self.display()))
    }

@@ -102,7 +108,7 @@ impl AsChunk for &Path {
 }

 impl AsChunk for PathBuf {
-    fn name(&self) -> Option<StdString> {
+    fn name(&self) -> Option<String> {
        Some(format!("@{}", self.display()))
    }

@@ -112,7 +118,7 @@ impl AsChunk for PathBuf {
 }

 impl<C: AsChunk + ?Sized> AsChunk for Box<C> {
-    fn name(&self) -> Option<StdString> {
+    fn name(&self) -> Option<String> {
        (**self).name()
    }

@@ -136,7 +142,7 @@ impl<C: AsChunk + ?Sized> AsChunk for Box<C> {
 #[must_use = "`Chunk`s do nothing unless one of `exec`, `eval`, `call`, or `into_function` are called on them"]
 pub struct Chunk<'a> {
    pub(crate) lua: WeakLua,
-    pub(crate) name: StdString,
+    pub(crate) name: String,
    pub(crate) env: Result<Option<Table>>,
    pub(crate) mode: Option<ChunkMode>,
    pub(crate) source: IoResult<Cow<'a, [u8]>>,
@@ -154,13 +160,14 @@ pub enum ChunkMode {
 /// Represents a constant value that can be used by Luau compiler.
 #[cfg(any(feature = "luau", doc))]
 #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+#[non_exhaustive]
 #[derive(Clone, Debug)]
 pub enum CompileConstant {
    Nil,
    Boolean(bool),
    Number(crate::Number),
    Vector(crate::Vector),
-    String(StdString),
+    String(String),
 }

 #[cfg(any(feature = "luau", doc))]
@@ -192,7 +199,7 @@ impl From<&str> for CompileConstant {
 }

 #[cfg(any(feature = "luau", doc))]
-type LibraryMemberConstantMap = HashMap<(StdString, StdString), CompileConstant>;
+type LibraryMemberConstantMap = HashMap<(String, String), CompileConstant>;

 /// Luau compiler
 #[cfg(any(feature = "luau", doc))]
@@ -203,14 +210,14 @@ pub struct Compiler {
    debug_level: u8,
    type_info_level: u8,
    coverage_level: u8,
-    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>,
+    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>,
    library_constants: Option<LibraryMemberConstantMap>,
-    disabled_builtins: Vec<StdString>,
+    disabled_builtins: Vec<String>,
 }

 #[cfg(any(feature = "luau", doc))]
@@ -294,7 +301,7 @@ impl Compiler {
    /// To set the library and method name, use the `lib.ctor` format.
    #[doc(hidden)]
    #[must_use]
-    pub fn set_vector_ctor(mut self, ctor: impl Into<StdString>) -> Self {
+    pub fn set_vector_ctor(mut self, ctor: impl Into<String>) -> Self {
        let ctor = ctor.into();
        let lib_ctor = ctor.split_once('.');
        self.vector_lib = lib_ctor.as_ref().map(|&(lib, _)| lib.to_owned());
@@ -307,7 +314,7 @@ impl Compiler {
    /// Sets alternative vector type name for type tables, in addition to default type `vector`.
    #[doc(hidden)]
    #[must_use]
-    pub fn set_vector_type(mut self, r#type: impl Into<StdString>) -> Self {
+    pub fn set_vector_type(mut self, r#type: impl Into<String>) -> Self {
        self.vector_type = Some(r#type.into());
        self
    }
@@ -316,7 +323,7 @@ impl Compiler {
    ///
    /// It disables the import optimization for fields accessed through it.
    #[must_use]
-    pub fn add_mutable_global(mut self, global: impl Into<StdString>) -> Self {
+    pub fn add_mutable_global(mut self, global: impl Into<String>) -> Self {
        self.mutable_globals.push(global.into());
        self
    }
@@ -325,21 +332,21 @@ impl Compiler {
    ///
    /// It disables the import optimization for fields accessed through these.
    #[must_use]
-    pub fn set_mutable_globals<S: Into<StdString>>(mut self, globals: impl IntoIterator<Item = S>) -> Self {
+    pub fn set_mutable_globals<S: Into<String>>(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 {
+    pub fn add_userdata_type(mut self, r#type: impl Into<String>) -> 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<StdString>>(mut self, types: impl IntoIterator<Item = S>) -> Self {
+    pub fn set_userdata_types<S: Into<String>>(mut self, types: impl IntoIterator<Item = S>) -> Self {
        self.userdata_types = types.into_iter().map(|s| s.into()).collect();
        self
    }
@@ -366,24 +373,21 @@ impl Compiler {
            self.libraries_with_known_members.push(lib.clone());
        }
        self.library_constants
-            .get_or_insert_with(HashMap::new)
+            .get_or_insert_default()
            .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 {
+    pub fn add_disabled_builtin(mut self, builtin: impl Into<String>) -> 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<StdString>>(
-        mut self,
-        builtins: impl IntoIterator<Item = S>,
-    ) -> Self {
+    pub fn set_disabled_builtins<S: Into<String>>(mut self, builtins: impl IntoIterator<Item = S>) -> Self {
        self.disabled_builtins = builtins.into_iter().map(|s| s.into()).collect();
        self
    }
@@ -477,11 +481,11 @@ impl Compiler {
            options.mutableGlobals = mutable_globals_ptr;
            options.userdataTypes = userdata_types_ptr;
            options.librariesWithKnownMembers = libraries_with_known_members_ptr;
-            if let Some(map) = self.library_constants.as_ref() {
-                if !self.libraries_with_known_members.is_empty() {
-                    LIBRARY_MEMBER_CONSTANT_MAP.with_borrow_mut(|gmap| *gmap = map.clone());
-                    options.libraryMemberConstantCallback = Some(library_member_constant_callback);
-                }
+            if let Some(map) = self.library_constants.as_ref()
+                && !self.libraries_with_known_members.is_empty()
+            {
+                LIBRARY_MEMBER_CONSTANT_MAP.with_borrow_mut(|gmap| *gmap = map.clone());
+                options.libraryMemberConstantCallback = Some(library_member_constant_callback);
            }
            options.disabledBuiltins = disabled_builtins_ptr;
            ffi::luau_compile(source.as_ref(), options)
@@ -490,7 +494,7 @@ 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 = StdString::from_utf8_lossy(&bytecode[2..]).into_owned();
+            let message = String::from_utf8_lossy(&bytecode[2..]).into_owned();
            return Err(Error::SyntaxError {
                incomplete_input: message.ends_with("<eof>"),
                message,
@@ -513,7 +517,7 @@ 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<StdString>) -> Self {
+    pub fn set_name(mut self, name: impl Into<String>) -> Self {
        self.name = name.into();
        self
    }
@@ -662,19 +666,19 @@ impl Chunk<'_> {
    ///
    /// It does nothing if the chunk is already binary or invalid.
    fn compile(&mut self) {
-        if let Ok(ref source) = self.source {
-            if self.detect_mode() == ChunkMode::Text {
-                #[cfg(feature = "luau")]
-                if let Ok(data) = self.compiler.get_or_insert_with(Default::default).compile(source) {
-                    self.source = Ok(Cow::Owned(data));
-                    self.mode = Some(ChunkMode::Binary);
-                }
-                #[cfg(not(feature = "luau"))]
-                if let Ok(func) = self.lua.lock().load_chunk(None, None, None, source.as_ref()) {
-                    let data = func.dump(false);
-                    self.source = Ok(Cow::Owned(data));
-                    self.mode = Some(ChunkMode::Binary);
-                }
+        if let Ok(ref source) = self.source
+            && self.detect_mode() == ChunkMode::Text
+        {
+            #[cfg(feature = "luau")]
+            if let Ok(data) = self.compiler.get_or_insert_default().compile(source) {
+                self.source = Ok(Cow::Owned(data));
+                self.mode = Some(ChunkMode::Binary);
+            }
+            #[cfg(not(feature = "luau"))]
+            if let Ok(func) = self.lua.lock().load_chunk(None, None, None, source.as_ref()) {
+                let data = func.dump(false);
+                self.source = Ok(Cow::Owned(data));
+                self.mode = Some(ChunkMode::Binary);
            }
        }
    }
@@ -687,33 +691,33 @@ impl Chunk<'_> {

        // Try to fetch compiled chunk from cache
        let mut text_source = None;
-        if let Ok(ref source) = self.source {
-            if self.detect_mode() == ChunkMode::Text {
-                let lua = self.lua.lock();
-                if let Some(cache) = lua.priv_app_data_ref::<ChunksCache>() {
-                    if let Some(data) = cache.0.get(source.as_ref()) {
-                        self.source = Ok(Cow::Owned(data.clone()));
-                        self.mode = Some(ChunkMode::Binary);
-                        return self;
-                    }
-                }
-                text_source = Some(source.as_ref().to_vec());
+        if let Ok(ref source) = self.source
+            && self.detect_mode() == ChunkMode::Text
+        {
+            let lua = self.lua.lock();
+            if let Some(cache) = lua.priv_app_data_ref::<ChunksCache>()
+                && let Some(data) = cache.0.get(source.as_ref())
+            {
+                self.source = Ok(Cow::Owned(data.clone()));
+                self.mode = Some(ChunkMode::Binary);
+                return self;
            }
+            text_source = Some(source.as_ref().to_vec());
        }

        // Compile and cache the chunk
        if let Some(text_source) = text_source {
            self.compile();
-            if let Ok(ref binary_source) = self.source {
-                if self.detect_mode() == ChunkMode::Binary {
-                    let lua = self.lua.lock();
-                    if let Some(mut cache) = lua.priv_app_data_mut::<ChunksCache>() {
-                        cache.0.insert(text_source, binary_source.to_vec());
-                    } else {
-                        let mut cache = ChunksCache(HashMap::new());
-                        cache.0.insert(text_source, binary_source.to_vec());
-                        lua.set_priv_app_data(cache);
-                    };
+            if let Ok(ref binary_source) = self.source
+                && self.detect_mode() == ChunkMode::Binary
+            {
+                let lua = self.lua.lock();
+                if let Some(mut cache) = lua.priv_app_data_mut::<ChunksCache>() {
+                    cache.0.insert(text_source, binary_source.to_vec());
+                } else {
+                    let mut cache = ChunksCache(HashMap::new());
+                    cache.0.insert(text_source, binary_source.to_vec());
+                    lua.set_priv_app_data(cache);
                }
            }
        }
@@ -761,7 +765,7 @@ impl Chunk<'_> {
        ChunkMode::Text
    }

-    fn convert_name(name: StdString) -> Result<CString> {
+    fn convert_name(name: String) -> Result<CString> {
        CString::new(name).map_err(|err| Error::runtime(format!("invalid name: {err}")))
    }

@@ -783,7 +787,6 @@ impl Chunk<'_> {
    ///
    /// The resulted `IntoLua` implementation will convert the chunk into a Lua function without
    /// executing it.
-    #[doc(hidden)]
    #[track_caller]
    pub fn wrap(chunk: impl AsChunk) -> impl IntoLua {
        WrappedChunk {
@@ -4,20 +4,19 @@ use std::ffi::{CStr, CString, OsStr, OsString};
 use std::hash::{BuildHasher, Hash};
 use std::os::raw::c_int;
 use std::path::{Path, PathBuf};
-use std::string::String as StdString;
-use std::{mem, slice, str};
+use std::{slice, str};

-use bstr::{BStr, BString, ByteSlice, ByteVec};
+use bstr::{BStr, BString, ByteVec};
 use num_traits::cast;

 use crate::error::{Error, Result};
 use crate::function::Function;
 use crate::state::{Lua, RawLua};
-use crate::string::{BorrowedBytes, BorrowedStr, String};
+use crate::string::{BorrowedBytes, BorrowedStr, LuaString};
 use crate::table::Table;
 use crate::thread::Thread;
 use crate::traits::{FromLua, IntoLua, ShortTypeName as _};
-use crate::types::{Either, LightUserData, MaybeSend, RegistryKey};
+use crate::types::{Either, LightUserData, MaybeSend, MaybeSync, RegistryKey};
 use crate::userdata::{AnyUserData, UserData};
 use crate::value::{Nil, Value};

@@ -47,14 +46,14 @@ impl FromLua for Value {
    }
 }

-impl IntoLua for String {
+impl IntoLua for LuaString {
    #[inline]
    fn into_lua(self, _: &Lua) -> Result<Value> {
        Ok(Value::String(self))
    }
 }

-impl IntoLua for &String {
+impl IntoLua for &LuaString {
    #[inline]
    fn into_lua(self, _: &Lua) -> Result<Value> {
        Ok(Value::String(self.clone()))
@@ -67,16 +66,12 @@ impl IntoLua for &String {
    }
 }

-impl FromLua for String {
+impl FromLua for LuaString {
    #[inline]
-    fn from_lua(value: Value, lua: &Lua) -> Result<String> {
+    fn from_lua(value: Value, lua: &Lua) -> Result<LuaString> {
        let ty = value.type_name();
        lua.coerce_string(value)?
-            .ok_or_else(|| Error::FromLuaConversionError {
-                from: ty,
-                to: "string".to_string(),
-                message: Some("expected string or number".to_string()),
-            })
+            .ok_or_else(|| Error::from_lua_conversion(ty, "string", "expected string or number".to_string()))
    }

    unsafe fn from_stack(idx: c_int, lua: &RawLua) -> Result<Self> {
@@ -84,98 +79,86 @@ impl FromLua for String {
        let type_id = ffi::lua_type(state, idx);
        if type_id == ffi::LUA_TSTRING {
            ffi::lua_xpush(state, lua.ref_thread(), idx);
-            return Ok(String(lua.pop_ref_thread()));
+            return Ok(LuaString(lua.pop_ref_thread()));
        }
        // Fallback to default
        Self::from_lua(lua.stack_value(idx, Some(type_id)), lua.lua())
    }
 }

-impl IntoLua for BorrowedStr<'_> {
+impl IntoLua for BorrowedStr {
    #[inline]
    fn into_lua(self, _: &Lua) -> Result<Value> {
-        Ok(Value::String(self.borrow.into_owned()))
+        Ok(Value::String(LuaString(self.vref)))
    }

    #[inline]
    unsafe fn push_into_stack(self, lua: &RawLua) -> Result<()> {
-        lua.push_ref(&self.borrow.0);
+        lua.push_ref(&self.vref);
        Ok(())
    }
 }

-impl IntoLua for &BorrowedStr<'_> {
+impl IntoLua for &BorrowedStr {
    #[inline]
    fn into_lua(self, _: &Lua) -> Result<Value> {
-        Ok(Value::String(self.borrow.clone().into_owned()))
+        Ok(Value::String(LuaString(self.vref.clone())))
    }

    #[inline]
    unsafe fn push_into_stack(self, lua: &RawLua) -> Result<()> {
-        lua.push_ref(&self.borrow.0);
+        lua.push_ref(&self.vref);
        Ok(())
    }
 }

-impl FromLua for BorrowedStr<'_> {
+impl FromLua for BorrowedStr {
    fn from_lua(value: Value, lua: &Lua) -> Result<Self> {
-        let s = String::from_lua(value, lua)?;
-        let BorrowedStr { buf, _lua, .. } = BorrowedStr::try_from(&s)?;
-        let buf = unsafe { mem::transmute::<&str, &'static str>(buf) };
-        let borrow = Cow::Owned(s);
-        Ok(Self { buf, borrow, _lua })
+        let s = LuaString::from_lua(value, lua)?;
+        BorrowedStr::try_from(&s)
    }

    unsafe fn from_stack(idx: c_int, lua: &RawLua) -> Result<Self> {
-        let s = String::from_stack(idx, lua)?;
-        let BorrowedStr { buf, _lua, .. } = BorrowedStr::try_from(&s)?;
-        let buf = unsafe { mem::transmute::<&str, &'static str>(buf) };
-        let borrow = Cow::Owned(s);
-        Ok(Self { buf, borrow, _lua })
+        let s = LuaString::from_stack(idx, lua)?;
+        BorrowedStr::try_from(&s)
    }
 }

-impl IntoLua for BorrowedBytes<'_> {
+impl IntoLua for BorrowedBytes {
    #[inline]
    fn into_lua(self, _: &Lua) -> Result<Value> {
-        Ok(Value::String(self.borrow.into_owned()))
+        Ok(Value::String(LuaString(self.vref)))
    }

    #[inline]
    unsafe fn push_into_stack(self, lua: &RawLua) -> Result<()> {
-        lua.push_ref(&self.borrow.0);
+        lua.push_ref(&self.vref);
        Ok(())
    }
 }

-impl IntoLua for &BorrowedBytes<'_> {
+impl IntoLua for &BorrowedBytes {
    #[inline]
    fn into_lua(self, _: &Lua) -> Result<Value> {
-        Ok(Value::String(self.borrow.clone().into_owned()))
+        Ok(Value::String(LuaString(self.vref.clone())))
    }

    #[inline]
    unsafe fn push_into_stack(self, lua: &RawLua) -> Result<()> {
-        lua.push_ref(&self.borrow.0);
+        lua.push_ref(&self.vref);
        Ok(())
    }
 }

-impl FromLua for BorrowedBytes<'_> {
+impl FromLua for BorrowedBytes {
    fn from_lua(value: Value, lua: &Lua) -> Result<Self> {
-        let s = String::from_lua(value, lua)?;
-        let BorrowedBytes { buf, _lua, .. } = BorrowedBytes::from(&s);
-        let buf = unsafe { mem::transmute::<&[u8], &'static [u8]>(buf) };
-        let borrow = Cow::Owned(s);
-        Ok(Self { buf, borrow, _lua })
+        let s = LuaString::from_lua(value, lua)?;
+        Ok(BorrowedBytes::from(&s))
    }

    unsafe fn from_stack(idx: c_int, lua: &RawLua) -> Result<Self> {
-        let s = String::from_stack(idx, lua)?;
-        let BorrowedBytes { buf, _lua, .. } = BorrowedBytes::from(&s);
-        let buf = unsafe { mem::transmute::<&[u8], &'static [u8]>(buf) };
-        let borrow = Cow::Owned(s);
-        Ok(Self { buf, borrow, _lua })
+        let s = LuaString::from_stack(idx, lua)?;
+        Ok(BorrowedBytes::from(&s))
    }
 }

@@ -204,11 +187,7 @@ impl FromLua for Table {
    fn from_lua(value: Value, _: &Lua) -> Result<Table> {
        match value {
            Value::Table(table) => Ok(table),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "table".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(value.type_name(), "table", None)),
        }
    }
 }
@@ -238,11 +217,7 @@ impl FromLua for Function {
    fn from_lua(value: Value, _: &Lua) -> Result<Function> {
        match value {
            Value::Function(table) => Ok(table),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "function".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(value.type_name(), "function", None)),
        }
    }
 }
@@ -272,11 +247,7 @@ impl FromLua for Thread {
    fn from_lua(value: Value, _: &Lua) -> Result<Thread> {
        match value {
            Value::Thread(t) => Ok(t),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "thread".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(value.type_name(), "thread", None)),
        }
    }
 }
@@ -306,16 +277,12 @@ impl FromLua for AnyUserData {
    fn from_lua(value: Value, _: &Lua) -> Result<AnyUserData> {
        match value {
            Value::UserData(ud) => Ok(ud),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "userdata".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(value.type_name(), "userdata", None)),
        }
    }
 }

-impl<T: UserData + MaybeSend + 'static> IntoLua for T {
+impl<T: UserData + MaybeSend + MaybeSync + 'static> IntoLua for T {
    #[inline]
    fn into_lua(self, lua: &Lua) -> Result<Value> {
        Ok(Value::UserData(lua.create_userdata(self)?))
@@ -428,11 +395,11 @@ impl FromLua for LightUserData {
    fn from_lua(value: Value, _: &Lua) -> Result<Self> {
        match value {
            Value::LightUserData(ud) => Ok(ud),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "lightuserdata".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(
+                value.type_name(),
+                "lightuserdata",
+                None,
+            )),
        }
    }
 }
@@ -451,11 +418,7 @@ impl FromLua for crate::Vector {
    fn from_lua(value: Value, _: &Lua) -> Result<Self> {
        match value {
            Value::Vector(v) => Ok(v),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "vector".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(value.type_name(), "vector", None)),
        }
    }
 }
@@ -488,16 +451,12 @@ impl FromLua for crate::Buffer {
    fn from_lua(value: Value, _: &Lua) -> Result<Self> {
        match value {
            Value::Buffer(buf) => Ok(buf),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: "buffer".to_string(),
-                message: None,
-            }),
+            _ => Err(Error::from_lua_conversion(value.type_name(), "buffer", None)),
        }
    }
 }

-impl IntoLua for StdString {
+impl IntoLua for String {
    #[inline]
    fn into_lua(self, lua: &Lua) -> Result<Value> {
        #[cfg(feature = "lua55")]
@@ -519,16 +478,14 @@ impl IntoLua for StdString {
    }
 }

-impl FromLua for StdString {
+impl FromLua for String {
    #[inline]
    fn from_lua(value: Value, lua: &Lua) -> Result<Self> {
        let ty = value.type_name();
        Ok(lua
            .coerce_string(value)?
-            .ok_or_else(|| Error::FromLuaConversionError {
-                from: ty,
-                to: Self::type_name(),
-                message: Some("expected string or number".to_string()),
+            .ok_or_else(|| {
+                Error::from_lua_conversion(ty, Self::type_name(), "expected string or number".to_string())
            })?
            .to_str()?
            .to_owned())
@@ -544,11 +501,7 @@ impl FromLua for StdString {
            let bytes = slice::from_raw_parts(data as *const u8, size);
            return str::from_utf8(bytes)
                .map(|s| s.to_owned())
-                .map_err(|e| Error::FromLuaConversionError {
-                    from: "string",
-                    to: Self::type_name(),
-                    message: Some(e.to_string()),
-                });
+                .map_err(|e| Error::from_lua_conversion("string", Self::type_name(), e.to_string()));
        }
        // Fallback to default
        Self::from_lua(lua.stack_value(idx, Some(type_id)), lua.lua())
@@ -570,7 +523,10 @@ impl IntoLua for &str {
 impl IntoLua for Cow<'_, str> {
    #[inline]
    fn into_lua(self, lua: &Lua) -> Result<Value> {
-        Ok(Value::String(lua.create_string(self.as_bytes())?))
+        match self {
+            Cow::Borrowed(s) => s.into_lua(lua),
+            Cow::Owned(s) => s.into_lua(lua),
+        }
    }
 }

@@ -587,10 +543,8 @@ impl FromLua for Box<str> {
        let ty = value.type_name();
        Ok(lua
            .coerce_string(value)?
-            .ok_or_else(|| Error::FromLuaConversionError {
-                from: ty,
-                to: Self::type_name(),
-                message: Some("expected string or number".to_string()),
+            .ok_or_else(|| {
+                Error::from_lua_conversion(ty, Self::type_name(), "expected string or number".to_string())
            })?
            .to_str()?
            .to_owned()
@@ -614,21 +568,12 @@ impl FromLua for CString {
    #[inline]
    fn from_lua(value: Value, lua: &Lua) -> Result<Self> {
        let ty = value.type_name();
-        let string = lua
-            .coerce_string(value)?
-            .ok_or_else(|| Error::FromLuaConversionError {
-                from: ty,
-                to: Self::type_name(),
-                message: Some("expected string or number".to_string()),
-            })?;
-
+        let string = lua.coerce_string(value)?.ok_or_else(|| {
+            Error::from_lua_conversion(ty, Self::type_name(), "expected string or number".to_string())
+        })?;
        match CStr::from_bytes_with_nul(&string.as_bytes_with_nul()) {
            Ok(s) => Ok(s.into()),
-            Err(_) => Err(Error::FromLuaConversionError {
-                from: ty,
-                to: Self::type_name(),
-                message: Some("invalid C-style string".to_string()),
-            }),
+            Err(err) => Err(Error::from_lua_conversion(ty, Self::type_name(), err.to_string())),
        }
    }
 }
@@ -643,7 +588,10 @@ impl IntoLua for &CStr {
 impl IntoLua for Cow<'_, CStr> {
    #[inline]
    fn into_lua(self, lua: &Lua) -> Result<Value> {
-        Ok(Value::String(lua.create_string(self.to_bytes())?))
+        match self {
+            Cow::Borrowed(s) => s.into_lua(lua),
+            Cow::Owned(s) => s.into_lua(lua),
+        }
    }
 }

@@ -668,10 +616,8 @@ impl FromLua for BString {
            Value::Buffer(buf) => Ok(buf.to_vec().into()),
            _ => Ok((*lua
                .coerce_string(value)?
-                .ok_or_else(|| Error::FromLuaConversionError {
-                    from: ty,
-                    to: Self::type_name(),
-                    message: Some("expected string or number".to_string()),
+                .ok_or_else(|| {
+                    Error::from_lua_conversion(ty, Self::type_name(), "expected string or number".to_string())
                })?
                .as_bytes())
            .into()),
@@ -722,23 +668,22 @@ impl FromLua for OsString {
        let bs = BString::from_lua(value, lua)?;
        Vec::from(bs)
            .into_os_string()
-            .map_err(|err| Error::FromLuaConversionError {
-                from: ty,
-                to: "OsString".into(),
-                message: Some(err.to_string()),
-            })
+            .map_err(|err| Error::from_lua_conversion(ty, "OsString", err.to_string()))
    }
 }

 impl IntoLua for &OsStr {
+    #[cfg(unix)]
    #[inline]
    fn into_lua(self, lua: &Lua) -> Result<Value> {
-        let s = <[u8]>::from_os_str(self).ok_or_else(|| Error::ToLuaConversionError {
-            from: "OsStr".into(),
-            to: "string",
-            message: Some("invalid utf-8 encoding".into()),
-        })?;
-        Ok(Value::String(lua.create_string(s)?))
+        use std::os::unix::ffi::OsStrExt;
+        Ok(Value::String(lua.create_string(self.as_bytes())?))
+    }
+
+    #[cfg(not(unix))]
+    #[inline]
+    fn into_lua(self, lua: &Lua) -> Result<Value> {
+        self.display().to_string().into_lua(lua)
    }
 }

@@ -776,34 +721,25 @@ impl FromLua for char {
    fn from_lua(value: Value, _lua: &Lua) -> Result<Self> {
        let ty = value.type_name();
        match value {
-            Value::Integer(i) => {
-                cast(i)
-                    .and_then(char::from_u32)
-                    .ok_or_else(|| Error::FromLuaConversionError {
-                        from: ty,
-                        to: "char".to_string(),
-                        message: Some("integer out of range when converting to char".to_string()),
-                    })
-            }
+            Value::Integer(i) => cast(i).and_then(char::from_u32).ok_or_else(|| {
+                let msg = "integer out of range when converting to char";
+                Error::from_lua_conversion(ty, "char", msg.to_string())
+            }),
            Value::String(s) => {
                let str = s.to_str()?;
                let mut str_iter = str.chars();
                match (str_iter.next(), str_iter.next()) {
                    (Some(char), None) => Ok(char),
-                    _ => Err(Error::FromLuaConversionError {
-                        from: ty,
-                        to: "char".to_string(),
-                        message: Some(
-                            "expected string to have exactly one char when converting to char".to_string(),
-                        ),
-                    }),
+                    _ => {
+                        let msg = "expected string to have exactly one char when converting to char";
+                        Err(Error::from_lua_conversion(ty, "char", msg.to_string()))
+                    }
                }
            }
-            _ => Err(Error::FromLuaConversionError {
-                from: ty,
-                to: Self::type_name(),
-                message: Some("expected string or integer".to_string()),
-            }),
+            _ => {
+                let msg = "expected string or integer";
+                Err(Error::from_lua_conversion(ty, Self::type_name(), msg.to_string()))
+            }
        }
    }
 }
@@ -854,24 +790,14 @@ macro_rules! lua_convert_int {
                        if let Some(i) = lua.coerce_integer(value.clone())? {
                            cast(i)
                        } else {
-                            cast(
-                                lua.coerce_number(value)?
-                                    .ok_or_else(|| Error::FromLuaConversionError {
-                                        from: ty,
-                                        to: stringify!($x).to_string(),
-                                        message: Some(
-                                            "expected number or string coercible to number".to_string(),
-                                        ),
-                                    })?,
-                            )
+                            cast(lua.coerce_number(value)?.ok_or_else(|| {
+                                let msg = "expected number or string coercible to number";
+                                Error::from_lua_conversion(ty, stringify!($x), msg.to_string())
+                            })?)
                        }
                    }
                })
-                .ok_or_else(|| Error::FromLuaConversionError {
-                    from: ty,
-                    to: stringify!($x).to_string(),
-                    message: Some("out of range".to_owned()),
-                })
+                .ok_or_else(|| Error::from_lua_conversion(ty, stringify!($x), "out of range".to_string()))
            }

            unsafe fn from_stack(idx: c_int, lua: &RawLua) -> Result<Self> {
@@ -881,13 +807,18 @@ macro_rules! lua_convert_int {
                    let mut ok = 0;
                    let i = ffi::lua_tointegerx(state, idx, &mut ok);
                    if ok != 0 {
-                        return cast(i).ok_or_else(|| Error::FromLuaConversionError {
-                            from: "integer",
-                            to: stringify!($x).to_string(),
-                            message: Some("out of range".to_owned()),
+                        return cast(i).ok_or_else(|| {
+                            Error::from_lua_conversion("integer", stringify!($x), "out of range".to_string())
                        });
                    }
                }
+                #[cfg(feature = "luau")]
+                if type_id == ffi::LUA_TINTEGER {
+                    let i = ffi::lua_tointeger64(state, idx, std::ptr::null_mut());
+                    return cast(i).ok_or_else(|| {
+                        Error::from_lua_conversion("integer", stringify!($x), "out of range".to_string())
+                    });
+                }
                // Fallback to default
                Self::from_lua(lua.stack_value(idx, Some(type_id)), lua.lua())
            }
@@ -921,13 +852,10 @@ macro_rules! lua_convert_float {
            #[inline]
            fn from_lua(value: Value, lua: &Lua) -> Result<Self> {
                let ty = value.type_name();
-                lua.coerce_number(value)?
-                    .map(|n| n as $x)
-                    .ok_or_else(|| Error::FromLuaConversionError {
-                        from: ty,
-                        to: stringify!($x).to_string(),
-                        message: Some("expected number or string coercible to number".to_string()),
-                    })
+                lua.coerce_number(value)?.map(|n| n as $x).ok_or_else(|| {
+                    let msg = "expected number or string coercible to number";
+                    Error::from_lua_conversion(ty, stringify!($x), msg.to_string())
+                })
            }

            unsafe fn from_stack(idx: c_int, lua: &RawLua) -> Result<Self> {
@@ -987,18 +915,16 @@ where
            },
            Value::Table(table) => {
                let vec = table.sequence_values().collect::<Result<Vec<_>>>()?;
-                vec.try_into()
-                    .map_err(|vec: Vec<T>| Error::FromLuaConversionError {
-                        from: "table",
-                        to: Self::type_name(),
-                        message: Some(format!("expected table of length {N}, got {}", vec.len())),
-                    })
+                vec.try_into().map_err(|vec: Vec<T>| {
+                    let msg = format!("expected table of length {N}, got {}", vec.len());
+                    Error::from_lua_conversion("table", Self::type_name(), msg)
+                })
+            }
+            _ => {
+                let msg = format!("expected table of length {N}");
+                let err = Error::from_lua_conversion(value.type_name(), Self::type_name(), msg.to_string());
+                Err(err)
            }
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: Self::type_name(),
-                message: Some("expected table".to_string()),
-            }),
        }
    }
 }
@@ -1029,11 +955,11 @@ impl<T: FromLua> FromLua for Vec<T> {
    fn from_lua(value: Value, _lua: &Lua) -> Result<Self> {
        match value {
            Value::Table(table) => table.sequence_values().collect(),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: Self::type_name(),
-                message: Some("expected table".to_string()),
-            }),
+            _ => Err(Error::from_lua_conversion(
+                value.type_name(),
+                Self::type_name(),
+                "expected table".to_string(),
+            )),
        }
    }
 }
@@ -1048,14 +974,13 @@ impl<K: Eq + Hash + IntoLua, V: IntoLua, S: BuildHasher> IntoLua for HashMap<K,
 impl<K: Eq + Hash + FromLua, V: FromLua, S: BuildHasher + Default> FromLua for HashMap<K, V, S> {
    #[inline]
    fn from_lua(value: Value, _: &Lua) -> Result<Self> {
-        if let Value::Table(table) = value {
-            table.pairs().collect()
-        } else {
-            Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: Self::type_name(),
-                message: Some("expected table".to_string()),
-            })
+        match value {
+            Value::Table(table) => table.pairs().collect(),
+            _ => Err(Error::from_lua_conversion(
+                value.type_name(),
+                Self::type_name(),
+                "expected table".to_string(),
+            )),
        }
    }
 }
@@ -1070,14 +995,13 @@ impl<K: Ord + IntoLua, V: IntoLua> IntoLua for BTreeMap<K, V> {
 impl<K: Ord + FromLua, V: FromLua> FromLua for BTreeMap<K, V> {
    #[inline]
    fn from_lua(value: Value, _: &Lua) -> Result<Self> {
-        if let Value::Table(table) = value {
-            table.pairs().collect()
-        } else {
-            Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: Self::type_name(),
-                message: Some("expected table".to_string()),
-            })
+        match value {
+            Value::Table(table) => table.pairs().collect(),
+            _ => Err(Error::from_lua_conversion(
+                value.type_name(),
+                Self::type_name(),
+                "expected table".to_string(),
+            )),
        }
    }
 }
@@ -1097,11 +1021,11 @@ impl<T: Eq + Hash + FromLua, S: BuildHasher + Default> FromLua for HashSet<T, S>
        match value {
            Value::Table(table) if table.raw_len() > 0 => table.sequence_values().collect(),
            Value::Table(table) => table.pairs::<T, Value>().map(|res| res.map(|(k, _)| k)).collect(),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: Self::type_name(),
-                message: Some("expected table".to_string()),
-            }),
+            _ => Err(Error::from_lua_conversion(
+                value.type_name(),
+                Self::type_name(),
+                "expected table".to_string(),
+            )),
        }
    }
 }
@@ -1121,11 +1045,11 @@ impl<T: Ord + FromLua> FromLua for BTreeSet<T> {
        match value {
            Value::Table(table) if table.raw_len() > 0 => table.sequence_values().collect(),
            Value::Table(table) => table.pairs::<T, Value>().map(|res| res.map(|(k, _)| k)).collect(),
-            _ => Err(Error::FromLuaConversionError {
-                from: value.type_name(),
-                to: Self::type_name(),
-                message: Some("expected table".to_string()),
-            }),
+            _ => Err(Error::from_lua_conversion(
+                value.type_name(),
+                Self::type_name(),
+                "expected table".to_string(),
+            )),
        }
    }
 }
@@ -1195,11 +1119,11 @@ impl<L: FromLua, R: FromLua> FromLua for Either<L, R> {
            // Try the right type
            Err(_) => match R::from_lua(value, lua).map(Either::Right) {
                Ok(r) => Ok(r),
-                Err(_) => Err(Error::FromLuaConversionError {
-                    from: value_type_name,
-                    to: Self::type_name(),
-                    message: None,
-                }),
+                Err(_) => Err(Error::from_lua_conversion(
+                    value_type_name,
+                    Self::type_name(),
+                    None,
+                )),
            },
        }
    }
@@ -1211,13 +1135,12 @@ 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::lua_typename(lua.state(), ffi::lua_type(lua.state(), idx)));
-                    Err(Error::FromLuaConversionError {
-                        from: value_type_name.to_str().unwrap(),
-                        to: Self::type_name(),
-                        message: None,
-                    })
+                    let state = lua.state();
+                    let from_type_name = CStr::from_ptr(ffi::lua_typename(state, ffi::lua_type(state, idx)))
+                        .to_str()
+                        .unwrap_or("unknown");
+                    let err = Error::from_lua_conversion(from_type_name, Self::type_name(), None);
+                    Err(err)
                }
            },
        }
@@ -1,3 +1,9 @@
+//! Lua debugging interface.
+//!
+//! This module provides access to the Lua debug interface, allowing inspection of the call stack,
+//! and function information. The main types are [`struct@Debug`] for accessing debug information
+//! and [`HookTriggers`] for configuring debug hooks.
+
 use std::borrow::Cow;
 use std::os::raw::c_int;

@@ -5,7 +11,7 @@ use ffi::{lua_Debug, lua_State};

 use crate::function::Function;
 use crate::state::RawLua;
-use crate::util::{assert_stack, linenumber_to_usize, ptr_to_lossy_str, ptr_to_str, StackGuard};
+use crate::util::{StackGuard, assert_stack, linenumber_to_usize, ptr_to_lossy_str, ptr_to_str};

 /// Contains information about currently executing Lua code.
 ///
@@ -133,12 +139,6 @@ impl<'a> Debug<'a> {
        }
    }

-    #[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 {
@@ -190,15 +190,15 @@ impl<'a> Debug<'a> {

            #[cfg(not(feature = "luau"))]
            let stack = DebugStack {
-                num_ups: (*self.ar).nups as _,
-                #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
+                num_upvalues: (*self.ar).nups as _,
+                #[cfg(not(any(feature = "lua51", feature = "luajit")))]
                num_params: (*self.ar).nparams as _,
-                #[cfg(any(feature = "lua55", feature = "lua54", feature = "lua53", feature = "lua52"))]
+                #[cfg(not(any(feature = "lua51", feature = "luajit")))]
                is_vararg: (*self.ar).isvararg != 0,
            };
            #[cfg(feature = "luau")]
            let stack = DebugStack {
-                num_ups: (*self.ar).nupvals,
+                num_upvalues: (*self.ar).nupvals,
                num_params: (*self.ar).nparams,
                is_vararg: (*self.ar).isvararg != 0,
            };
@@ -208,6 +208,8 @@ impl<'a> Debug<'a> {
 }

 /// Represents a specific event that triggered the hook.
+#[cfg(not(feature = "luau"))]
+#[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum DebugEvent {
    Call,
@@ -218,6 +220,9 @@ pub enum DebugEvent {
    Unknown(c_int),
 }

+/// Contains the name information of a function in the call stack.
+///
+/// Returned by the [`Debug::names`] method.
 #[derive(Clone, Debug)]
 pub struct DebugNames<'a> {
    /// A (reasonable) name of the function (`None` if the name cannot be found).
@@ -228,6 +233,9 @@ pub struct DebugNames<'a> {
    pub name_what: Option<&'static str>,
 }

+/// Contains the source information of a function in the call stack.
+///
+/// Returned by the [`Debug::source`] method.
 #[derive(Clone, Debug)]
 pub struct DebugSource<'a> {
    /// Source of the chunk that created the function.
@@ -243,47 +251,20 @@ pub struct DebugSource<'a> {
    pub what: &'static str,
 }

+/// Contains stack information about a function in the call stack.
+///
+/// Returned by the [`Debug::stack`] method.
 #[derive(Copy, Clone, Debug)]
 pub struct DebugStack {
-    /// Number of upvalues.
-    pub num_ups: u8,
-    /// Number of parameters.
-    #[cfg(any(
-        feature = "lua55",
-        feature = "lua54",
-        feature = "lua53",
-        feature = "lua52",
-        feature = "luau"
-    ))]
-    #[cfg_attr(
-        docsrs,
-        doc(cfg(any(
-            feature = "lua55",
-            feature = "lua54",
-            feature = "lua53",
-            feature = "lua52",
-            feature = "luau"
-        )))
-    )]
+    /// 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 vararg function.
-    #[cfg(any(
-        feature = "lua55",
-        feature = "lua54",
-        feature = "lua53",
-        feature = "lua52",
-        feature = "luau"
-    ))]
-    #[cfg_attr(
-        docsrs,
-        doc(cfg(any(
-            feature = "lua55",
-            feature = "lua54",
-            feature = "lua53",
-            feature = "lua52",
-            feature = "luau"
-        )))
-    )]
+    /// 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,
 }

@@ -361,6 +342,7 @@ impl HookTriggers {
    }

    // Compute the mask to pass to `lua_sethook`.
+    #[cfg(not(feature = "luau"))]
    pub(crate) const fn mask(&self) -> c_int {
        let mut mask: c_int = 0;
        if self.on_calls {
@@ -380,6 +362,7 @@ impl HookTriggers {

    // Returns the `count` parameter to pass to `lua_sethook`, if applicable. Otherwise, zero is
    // returned.
+    #[cfg(not(feature = "luau"))]
    pub(crate) const fn count(&self) -> c_int {
        match self.every_nth_instruction {
            Some(n) => n as c_int,
@@ -1,10 +1,14 @@
+//! Lua error handling.
+//!
+//! This module provides the [`Error`] type returned by all fallible `mlua` operations, together
+//! with extension traits for adapting Rust errors for use within Lua.
+
 use std::error::Error as StdError;
 use std::fmt;
 use std::io::Error as IoError;
 use std::net::AddrParseError;
 use std::result::Result as StdResult;
 use std::str::Utf8Error;
-use std::string::String as StdString;
 use std::sync::Arc;

 use crate::private::Sealed;
@@ -22,7 +26,7 @@ pub enum Error {
    /// Syntax error while parsing Lua source code.
    SyntaxError {
        /// The error message as returned by Lua.
-        message: StdString,
+        message: String,
        /// `true` if the error can likely be fixed by appending more input to the source code.
        ///
        /// This is useful for implementing REPLs as they can query the user for more input if this
@@ -34,20 +38,20 @@ pub enum Error {
    /// The Lua VM returns this error when a builtin operation is performed on incompatible types.
    /// Among other things, this includes invoking operators on wrong types (such as calling or
    /// indexing a `nil` value).
-    RuntimeError(StdString),
+    RuntimeError(String),
    /// Lua memory error, aka `LUA_ERRMEM`
    ///
    /// The Lua VM returns this error when the allocator does not return the requested memory, aka
    /// it is an out-of-memory error.
-    MemoryError(StdString),
+    MemoryError(String),
    /// Lua garbage collector error, aka `LUA_ERRGCMM`.
    ///
    /// The Lua VM returns this error when there is an error running a `__gc` metamethod.
    #[cfg(any(feature = "lua53", feature = "lua52", doc))]
    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua53", feature = "lua52"))))]
-    GarbageCollectorError(StdString),
+    GarbageCollectorError(String),
    /// Potentially unsafe action in safe mode.
-    SafetyError(StdString),
+    SafetyError(String),
    /// Memory control is not available.
    ///
    /// This error can only happen when Lua state was not created by us and does not have the
@@ -80,23 +84,14 @@ pub enum Error {
    /// (which is stored in the corresponding field).
    BadArgument {
        /// Function that was called.
-        to: Option<StdString>,
+        to: Option<String>,
        /// Argument position (usually starts from 1).
        pos: usize,
        /// Argument name.
-        name: Option<StdString>,
+        name: Option<String>,
        /// Underlying error returned when converting argument to a Lua value.
        cause: Arc<Error>,
    },
-    /// A Rust value could not be converted to a Lua value.
-    ToLuaConversionError {
-        /// Name of the Rust type that could not be converted.
-        from: String,
-        /// Name of the Lua type that could not be created.
-        to: &'static str,
-        /// A message indicating why the conversion failed in more detail.
-        message: Option<StdString>,
-    },
    /// A Lua value could not be converted to the expected Rust type.
    FromLuaConversionError {
        /// Name of the Lua type that could not be converted.
@@ -104,7 +99,7 @@ pub enum Error {
        /// Name of the Rust type that could not be created.
        to: String,
        /// A string containing more detailed error information.
-        message: Option<StdString>,
+        message: Option<String>,
    },
    /// [`Thread::resume`] was called on an unresumable coroutine.
    ///
@@ -154,17 +149,17 @@ pub enum Error {
    /// A [`MetaMethod`] operation is restricted (typically for `__gc` or `__metatable`).
    ///
    /// [`MetaMethod`]: crate::MetaMethod
-    MetaMethodRestricted(StdString),
+    MetaMethodRestricted(String),
    /// A [`MetaMethod`] (eg. `__index` or `__newindex`) has invalid type.
    ///
    /// [`MetaMethod`]: crate::MetaMethod
    MetaMethodTypeError {
        /// Name of the metamethod.
-        method: StdString,
+        method: String,
        /// Passed value type.
        type_name: &'static str,
        /// A string containing more detailed error information.
-        message: Option<StdString>,
+        message: Option<String>,
    },
    /// A [`RegistryKey`] produced from a different Lua state was used.
    ///
@@ -173,7 +168,7 @@ pub enum Error {
    /// A Rust callback returned `Err`, raising the contained `Error` as a Lua error.
    CallbackError {
        /// Lua call stack backtrace.
-        traceback: StdString,
+        traceback: String,
        /// Original error returned by the Rust code.
        cause: Arc<Error>,
    },
@@ -185,11 +180,11 @@ pub enum Error {
    /// Serialization error.
    #[cfg(feature = "serde")]
    #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
-    SerializeError(StdString),
+    SerializeError(String),
    /// Deserialization error.
    #[cfg(feature = "serde")]
    #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
-    DeserializeError(StdString),
+    DeserializeError(String),
    /// A custom error.
    ///
    /// This can be used for returning user-defined errors from callbacks.
@@ -201,7 +196,7 @@ pub enum Error {
    /// An error with additional context.
    WithContext {
        /// A string containing additional context.
-        context: StdString,
+        context: String,
        /// Underlying error.
        cause: Arc<Error>,
    },
@@ -225,7 +220,7 @@ impl fmt::Display for Error {
            }
            Error::SafetyError(msg) => {
                write!(fmt, "safety error: {msg}")
-            },
+            }
            Error::MemoryControlNotAvailable => {
                write!(fmt, "memory control is not available")
            }
@@ -238,10 +233,7 @@ impl fmt::Display for Error {
                fmt,
                "out of Lua stack, too many arguments to a Lua function or too many return values from a callback"
            ),
-            Error::BindError => write!(
-                fmt,
-                "too many arguments to Function::bind"
-            ),
+            Error::BindError => write!(fmt, "too many arguments to Function::bind"),
            Error::BadArgument { to, pos, name, cause } => {
                if let Some(name) = name {
                    write!(fmt, "bad argument `{name}`")?;
@@ -252,13 +244,6 @@ impl fmt::Display for Error {
                    write!(fmt, " to `{to}`")?;
                }
                write!(fmt, ": {cause}")
-            },
-            Error::ToLuaConversionError { from, to, message } => {
-                write!(fmt, "error converting {from} to Lua {to}")?;
-                match message {
-                    None => Ok(()),
-                    Some(message) => write!(fmt, " ({message})"),
-                }
            }
            Error::FromLuaConversionError { from, to, message } => {
                write!(fmt, "error converting Lua {from} to {to}")?;
@@ -273,7 +258,11 @@ impl fmt::Display for Error {
            Error::UserDataBorrowError => write!(fmt, "error borrowing userdata"),
            Error::UserDataBorrowMutError => write!(fmt, "error mutably borrowing userdata"),
            Error::MetaMethodRestricted(method) => write!(fmt, "metamethod {method} is restricted"),
-            Error::MetaMethodTypeError { method, type_name, message } => {
+            Error::MetaMethodTypeError {
+                method,
+                type_name,
+                message,
+            } => {
                write!(fmt, "metamethod {method} has unsupported type {type_name}")?;
                match message {
                    None => Ok(()),
@@ -286,7 +275,11 @@ impl fmt::Display for Error {
            Error::CallbackError { cause, traceback } => {
                // Trace errors down to the root
                let (mut cause, mut full_traceback) = (cause, None);
-                while let Error::CallbackError { cause: cause2, traceback: traceback2 } = &**cause {
+                while let Error::CallbackError {
+                    cause: cause2,
+                    traceback: traceback2,
+                } = &**cause
+                {
                    cause = cause2;
                    full_traceback = Some(traceback2);
                }
@@ -312,11 +305,11 @@ impl fmt::Display for Error {
            #[cfg(feature = "serde")]
            Error::SerializeError(err) => {
                write!(fmt, "serialize error: {err}")
-            },
+            }
            #[cfg(feature = "serde")]
            Error::DeserializeError(err) => {
                write!(fmt, "deserialize error: {err}")
-            },
+            }
            Error::ExternalError(err) => err.fmt(fmt),
            Error::WithContext { context, cause } => {
                writeln!(fmt, "{context}")?;
@@ -352,7 +345,11 @@ impl Error {
    /// Wraps an external error object.
    #[inline]
    pub fn external<T: Into<Box<DynStdError>>>(err: T) -> Self {
-        Error::ExternalError(err.into().into())
+        let boxed = err.into();
+        match boxed.downcast::<Self>() {
+            Ok(err) => *err,
+            Err(boxed) => Error::ExternalError(boxed.into()),
+        }
    }

    /// Attempts to downcast the external error object to a concrete type by reference.
@@ -394,6 +391,7 @@ impl Error {
        }
    }

+    #[inline]
    pub(crate) fn from_lua_conversion(
        from: &'static str,
        to: impl ToString,
@@ -561,10 +559,8 @@ impl<'a> Iterator for Chain<'a> {

 #[cfg(test)]
 mod assertions {
-    use super::*;
-
    #[cfg(not(feature = "error-send"))]
-    static_assertions::assert_not_impl_any!(Error: Send, Sync);
+    static_assertions::assert_not_impl_any!(super::Error: Send, Sync);
    #[cfg(feature = "send")]
-    static_assertions::assert_impl_all!(Error: Send, Sync);
+    static_assertions::assert_impl_all!(super::Error: Send, Sync);
 }
@@ -1,24 +1,99 @@
+//! Lua function handling.
+//!
+//! This module provides types for working with Lua functions from Rust, including
+//! both Lua-defined functions and native Rust callbacks.
+//!
+//! # Calling Functions
+//!
+//! Use [`Function::call`] to invoke a Lua function synchronously:
+//!
+//! ```
+//! # use mlua::{Function, Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//!
+//! // Get a built-in function
+//! let print: Function = lua.globals().get("print")?;
+//! print.call::<()>("Hello from Rust!")?;
+//!
+//! // Call a function that returns values
+//! let tonumber: Function = lua.globals().get("tonumber")?;
+//! let n: i32 = tonumber.call("42")?;
+//! assert_eq!(n, 42);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! For asynchronous execution, use `Function::call_async` (requires `async` feature):
+//!
+//! ```ignore
+//! let result: String = my_async_func.call_async(args).await?;
+//! ```
+//!
+//! # Creating Functions
+//!
+//! Functions can be created from Rust closures using [`Lua::create_function`]:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//!
+//! let greet = lua.create_function(|_, name: String| {
+//!     Ok(format!("Hello, {}!", name))
+//! })?;
+//!
+//! lua.globals().set("greet", greet)?;
+//! let result: String = lua.load(r#"greet("World")"#).eval()?;
+//! assert_eq!(result, "Hello, World!");
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! For simpler cases, use [`Function::wrap`] or [`Function::wrap_raw`] to convert a Rust function
+//! directly:
+//!
+//! ```
+//! # use mlua::{Function, Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//!
+//! fn add(a: i32, b: i32) -> i32 { a + b }
+//!
+//! lua.globals().set("add", Function::wrap_raw(add))?;
+//! let sum: i32 = lua.load("add(2, 3)").eval()?;
+//! assert_eq!(sum, 5);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Function Environments
+//!
+//! Lua functions have an associated environment table that determines how global
+//! variables are resolved. Use [`Function::environment`] and [`Function::set_environment`]
+//! to inspect or modify this environment.
+
 use std::cell::RefCell;
 use std::os::raw::{c_int, c_void};
+use std::result::Result as StdResult;
 use std::{mem, ptr, slice};

-use crate::error::{Error, Result};
+use crate::error::{Error, ExternalError, ExternalResult, Result};
 use crate::state::Lua;
 use crate::table::Table;
-use crate::traits::{FromLuaMulti, IntoLua, IntoLuaMulti, LuaNativeFn, LuaNativeFnMut};
+use crate::traits::{FromLuaMulti, IntoLua, IntoLuaMulti};
 use crate::types::{Callback, LuaType, MaybeSend, ValueRef};
 use crate::util::{
-    assert_stack, check_stack, linenumber_to_usize, pop_error, ptr_to_lossy_str, ptr_to_str, StackGuard,
+    StackGuard, assert_stack, check_stack, linenumber_to_usize, pop_error, ptr_to_lossy_str, ptr_to_str,
 };
 use crate::value::Value;

 #[cfg(feature = "async")]
 use {
    crate::thread::AsyncThread,
-    crate::traits::LuaNativeAsyncFn,
    crate::types::AsyncCallback,
    std::future::{self, Future},
-    std::pin::{pin, Pin},
+    std::pin::{Pin, pin},
    std::task::{Context, Poll},
 };

@@ -165,7 +240,7 @@ impl Function {
    /// # }
    /// ```
    ///
-    /// [`AsyncThread`]: crate::AsyncThread
+    /// [`AsyncThread`]: crate::thread::AsyncThread
    #[cfg(feature = "async")]
    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
    pub fn call_async<R>(&self, args: impl IntoLuaMulti) -> AsyncCallFuture<R>
@@ -555,30 +630,32 @@ impl Function {
    /// Wraps a Rust function or closure, returning an opaque type that implements [`IntoLua`]
    /// trait.
    #[inline]
-    pub fn wrap<F, A, R>(func: F) -> impl IntoLua
+    pub fn wrap<F, A, R, E>(func: F) -> impl IntoLua
    where
-        F: LuaNativeFn<A, Output = Result<R>> + MaybeSend + 'static,
+        F: LuaNativeFn<A, Output = StdResult<R, E>> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
+        E: ExternalError,
    {
        WrappedFunction(Box::new(move |lua, nargs| unsafe {
            let args = A::from_stack_args(nargs, 1, None, lua)?;
-            func.call(args)?.push_into_stack_multi(lua)
+            func.call(args).into_lua_err()?.push_into_stack_multi(lua)
        }))
    }

    /// Wraps a Rust mutable closure, returning an opaque type that implements [`IntoLua`] trait.
-    pub fn wrap_mut<F, A, R>(func: F) -> impl IntoLua
+    pub fn wrap_mut<F, A, R, E>(func: F) -> impl IntoLua
    where
-        F: LuaNativeFnMut<A, Output = Result<R>> + MaybeSend + 'static,
+        F: LuaNativeFnMut<A, Output = StdResult<R, E>> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
+        E: ExternalError,
    {
        let func = RefCell::new(func);
        WrappedFunction(Box::new(move |lua, nargs| unsafe {
            let mut func = func.try_borrow_mut().map_err(|_| Error::RecursiveMutCallback)?;
            let args = A::from_stack_args(nargs, 1, None, lua)?;
-            func.call(args)?.push_into_stack_multi(lua)
+            func.call(args).into_lua_err()?.push_into_stack_multi(lua)
        }))
    }

@@ -591,6 +668,7 @@ impl Function {
    pub fn wrap_raw<F, A>(func: F) -> impl IntoLua
    where
        F: LuaNativeFn<A> + MaybeSend + 'static,
+        F::Output: IntoLuaMulti,
        A: FromLuaMulti,
    {
        WrappedFunction(Box::new(move |lua, nargs| unsafe {
@@ -607,6 +685,7 @@ impl Function {
    pub fn wrap_raw_mut<F, A>(func: F) -> impl IntoLua
    where
        F: LuaNativeFnMut<A> + MaybeSend + 'static,
+        F::Output: IntoLuaMulti,
        A: FromLuaMulti,
    {
        let func = RefCell::new(func);
@@ -621,11 +700,12 @@ impl Function {
    /// trait.
    #[cfg(feature = "async")]
    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-    pub fn wrap_async<F, A, R>(func: F) -> impl IntoLua
+    pub fn wrap_async<F, A, R, E>(func: F) -> impl IntoLua
    where
-        F: LuaNativeAsyncFn<A, Output = Result<R>> + MaybeSend + 'static,
+        F: LuaNativeAsyncFn<A, Output = StdResult<R, E>> + MaybeSend + 'static,
        A: FromLuaMulti,
        R: IntoLuaMulti,
+        E: ExternalError,
    {
        WrappedAsyncFunction(Box::new(move |rawlua, nargs| unsafe {
            let args = match A::from_stack_args(nargs, 1, None, rawlua) {
@@ -634,7 +714,7 @@ impl Function {
            };
            let lua = rawlua.lua();
            let fut = func.call(args);
-            Box::pin(async move { fut.await?.push_into_stack_multi(lua.raw_lua()) })
+            Box::pin(async move { fut.await.into_lua_err()?.push_into_stack_multi(lua.raw_lua()) })
        }))
    }

@@ -648,6 +728,7 @@ impl Function {
    pub fn wrap_raw_async<F, A>(func: F) -> impl IntoLua
    where
        F: LuaNativeAsyncFn<A> + MaybeSend + 'static,
+        F::Output: IntoLuaMulti,
        A: FromLuaMulti,
    {
        WrappedAsyncFunction(Box::new(move |rawlua, nargs| unsafe {
@@ -681,7 +762,9 @@ impl LuaType for Function {
    const TYPE_ID: c_int = ffi::LUA_TFUNCTION;
 }

+/// Future for asynchronous function calls.
 #[cfg(feature = "async")]
+#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct AsyncCallFuture<R: FromLuaMulti>(Result<AsyncThread<R>>);

@@ -705,6 +788,94 @@ impl<R: FromLuaMulti> Future for AsyncCallFuture<R> {
    }
 }

+/// A trait for types that can be used as Lua functions.
+pub trait LuaNativeFn<A: FromLuaMulti> {
+    type Output;
+
+    fn call(&self, args: A) -> Self::Output;
+}
+
+/// A trait for types with mutable state that can be used as Lua functions.
+pub trait LuaNativeFnMut<A: FromLuaMulti> {
+    type Output;
+
+    fn call(&mut self, args: A) -> Self::Output;
+}
+
+/// A trait for types that returns a future and can be used as Lua functions.
+#[cfg(feature = "async")]
+pub trait LuaNativeAsyncFn<A: FromLuaMulti> {
+    type Output;
+
+    fn call(&self, args: A) -> impl Future<Output = Self::Output> + MaybeSend + 'static;
+}
+
+macro_rules! impl_lua_native_fn {
+    ($($A:ident),*) => {
+        impl<FN, $($A,)* R> LuaNativeFn<($($A,)*)> for FN
+        where
+            FN: Fn($($A,)*) -> R + MaybeSend + 'static,
+            ($($A,)*): FromLuaMulti,
+        {
+            type Output = R;
+
+            #[allow(non_snake_case)]
+            fn call(&self, args: ($($A,)*)) -> Self::Output {
+                let ($($A,)*) = args;
+                self($($A,)*)
+            }
+        }
+
+        impl<FN, $($A,)* R> LuaNativeFnMut<($($A,)*)> for FN
+        where
+            FN: FnMut($($A,)*) -> R + MaybeSend + 'static,
+            ($($A,)*): FromLuaMulti,
+        {
+            type Output = R;
+
+            #[allow(non_snake_case)]
+            fn call(&mut self, args: ($($A,)*)) -> Self::Output {
+                let ($($A,)*) = args;
+                self($($A,)*)
+            }
+        }
+
+        #[cfg(feature = "async")]
+        impl<FN, $($A,)* Fut, R> LuaNativeAsyncFn<($($A,)*)> for FN
+        where
+            FN: Fn($($A,)*) -> Fut + MaybeSend + 'static,
+            ($($A,)*): FromLuaMulti,
+            Fut: Future<Output = R> + MaybeSend + 'static,
+        {
+            type Output = R;
+
+            #[allow(non_snake_case)]
+            fn call(&self, args: ($($A,)*)) -> impl Future<Output = Self::Output> + MaybeSend + 'static {
+                let ($($A,)*) = args;
+                self($($A,)*)
+            }
+        }
+    };
+}
+
+impl_lua_native_fn!();
+impl_lua_native_fn!(A);
+impl_lua_native_fn!(A, B);
+impl_lua_native_fn!(A, B, C);
+impl_lua_native_fn!(A, B, C, D);
+impl_lua_native_fn!(A, B, C, D, E);
+impl_lua_native_fn!(A, B, C, D, E, F);
+impl_lua_native_fn!(A, B, C, D, E, F, G);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M, N);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O);
+impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P);
+
 #[cfg(test)]
 mod assertions {
    use super::*;
@@ -61,91 +61,105 @@
 //! [`Future`]: std::future::Future
 //! [`serde::Serialize`]: https://docs.serde.rs/serde/ser/trait.Serialize.html
 //! [`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
+//! [`AsyncThread`]: crate::thread::AsyncThread

 // Deny warnings inside doc tests / examples. When this isn't present, rustdoc doesn't show *any*
 // warnings at all.
 #![cfg_attr(docsrs, feature(doc_cfg))]
 #![cfg_attr(not(send), allow(clippy::arc_with_non_send_sync))]
-#![allow(clippy::ptr_eq)]
 #![allow(unsafe_op_in_unsafe_fn)]

 #[macro_use]
 mod macros;

 mod buffer;
-mod chunk;
 mod conversion;
-mod debug;
-mod error;
-mod function;
-#[cfg(any(feature = "luau", doc))]
-mod luau;
 mod memory;
 mod multi;
 mod scope;
-mod state;
 mod stdlib;
-mod string;
-mod table;
-mod thread;
 mod traits;
 mod types;
-mod userdata;
 mod util;
 mod value;
 mod vector;

+pub mod chunk;
+pub mod debug;
+pub mod error;
+pub mod function;
+#[cfg(any(feature = "luau", doc))]
+#[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+pub mod luau;
 pub mod prelude;
+pub mod state;
+pub mod string;
+pub mod table;
+pub mod thread;
+pub mod userdata;

 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};
+#[doc(inline)]
+pub use crate::error::{Error, Result};
+#[doc(inline)]
+pub use crate::function::Function;
 pub use crate::multi::{MultiValue, Variadic};
 pub use crate::scope::Scope;
-pub use crate::state::{GCMode, Lua, LuaOptions, WeakLua};
+#[doc(inline)]
+pub use crate::state::{Lua, LuaOptions, WeakLua};
 pub use crate::stdlib::StdLib;
-pub use crate::string::{BorrowedBytes, BorrowedStr, String};
-pub use crate::table::{Table, TablePairs, TableSequence};
-pub use crate::thread::{Thread, ThreadStatus};
-pub use crate::traits::{
-    FromLua, FromLuaMulti, IntoLua, IntoLuaMulti, LuaNativeFn, LuaNativeFnMut, ObjectLike,
-};
+#[doc(inline)]
+pub use crate::string::{BorrowedBytes, BorrowedStr, LuaString};
+#[doc(inline)]
+pub use crate::table::Table;
+#[doc(inline)]
+pub use crate::thread::Thread;
+#[doc(inline)]
+pub use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti, ObjectLike};
 pub use crate::types::{
-    AppDataRef, AppDataRefMut, Either, Integer, LightUserData, MaybeSend, Number, RegistryKey, VmState,
-};
-pub use crate::userdata::{
-    AnyUserData, MetaMethod, UserData, UserDataFields, UserDataMetatable, UserDataMethods, UserDataRef,
-    UserDataRefMut, UserDataRegistry,
+    AppDataRef, AppDataRefMut, Either, Integer, LightUserData, MaybeSend, MaybeSync, Number, RegistryKey,
+    VmState,
 };
+#[doc(inline)]
+pub use crate::userdata::AnyUserData;
 pub use crate::value::{Nil, Value};

+// Re-export some types to keep backward compatibility and avoid breaking changes in the public API.
+#[doc(hidden)]
+pub use crate::chunk::{AsChunk, Chunk, ChunkMode};
+#[cfg(feature = "luau")]
+#[doc(hidden)]
+pub use crate::chunk::{CompileConstant, Compiler};
+#[doc(hidden)]
+pub use crate::error::{ErrorContext, ExternalError, ExternalResult};
+#[doc(hidden)]
+pub use crate::string::LuaString as String;
+#[doc(hidden)]
+pub use crate::table::{TablePairs, TableSequence};
+#[doc(hidden)]
+pub use crate::thread::ThreadStatus;
+#[doc(hidden)]
+pub use crate::userdata::{
+    MetaMethod, UserData, UserDataFields, UserDataMetatable, UserDataMethods, UserDataOwned, UserDataRef,
+    UserDataRefMut, UserDataRegistry,
+};
+
 #[cfg(not(feature = "luau"))]
+#[doc(inline)]
 pub use crate::debug::HookTriggers;

 #[cfg(any(feature = "luau", doc))]
 #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
-pub use crate::{
-    buffer::Buffer,
-    chunk::{CompileConstant, Compiler},
-    function::CoverageInfo,
-    luau::{HeapDump, NavigateError, Require, TextRequirer},
-    vector::Vector,
-};
-
-#[cfg(feature = "async")]
-#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-pub use crate::{thread::AsyncThread, traits::LuaNativeAsyncFn};
+pub use crate::{buffer::Buffer, vector::Vector};

+#[cfg(feature = "serde")]
+#[doc(hidden)]
+pub use crate::serde::{DeserializeOptions, SerializeOptions};
 #[cfg(feature = "serde")]
 #[doc(inline)]
-pub use crate::{
-    serde::{de::Options as DeserializeOptions, ser::Options as SerializeOptions, LuaSerdeExt},
-    value::SerializableValue,
-};
+pub use crate::{serde::LuaSerdeExt, value::SerializableValue};

 #[cfg(feature = "serde")]
 #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
@@ -246,10 +260,10 @@ pub use mlua_derive::FromLua;
 ///
 /// * skip_memory_check - skip memory allocation checks for some operations.
 ///
-/// In module mode, mlua runs in unknown environment and cannot say are there any memory
-/// limits or not. As result, some operations that require memory allocation runs in
-/// protected mode. Setting this attribute will improve performance of such operations
-/// with risk of having uncaught exceptions and memory leaks.
+/// In module mode, mlua runs in an unknown environment and cannot tell whether there are any memory
+/// limits or not. As a result, some operations that require memory allocation run in protected
+/// mode. Setting this attribute will improve performance of such operations with risk of having
+/// uncaught exceptions and memory leaks.
 ///
 /// ```ignore
 /// #[mlua::lua_module(skip_memory_check)]
@@ -79,10 +79,10 @@ impl HeapDump {
        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;
-                }
+            if let Some(cat_id) = category_id
+                && obj["cat"].as_i64()? != cat_id
+            {
+                continue;
            }
            update_size(&mut size_by_type, obj["type"].as_str()?, obj["size"].as_u64()?);
        }
@@ -123,18 +123,18 @@ impl HeapDump {
            if obj["type"] != "userdata" {
                continue;
            }
-            if let Some(cat_id) = category_id {
-                if obj["cat"].as_i64()? != cat_id {
-                    continue;
-                }
+            if let Some(cat_id) = category_id
+                && 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;
-                }
+            if let Some(metatable_addr) = obj["metatable"].as_str()
+                && 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()?);
        }
@@ -155,7 +155,7 @@ impl HeapDump {

 /// 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));
+    let (count, total_size) = size_type.entry(key).or_insert((0, 0));
    *count += 1;
    *total_size += size;
 }
@@ -1,3 +1,10 @@
+//! Luau-specific extensions and types.
+//!
+//! This module provides Luau-specific functionality including custom [`require`] implementations,
+//! heap memory analysis, and Luau VM integration utilities.
+//!
+//! [`require`]: crate::Lua::create_require_function
+
 use std::ffi::{CStr, CString};
 use std::os::raw::c_int;
 use std::ptr;
@@ -5,12 +12,12 @@ use std::ptr;
 use crate::chunk::ChunkMode;
 use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::state::{callback_error_ext, ExtraData, Lua};
+use crate::state::{ExtraData, Lua, callback_error_ext};
 use crate::traits::{FromLuaMulti, IntoLua};
 use crate::types::MaybeSend;

 pub use heap_dump::HeapDump;
-pub use require::{NavigateError, Require, TextRequirer};
+pub use require::{FsRequirer, NavigateError, Require};

 // Since Luau has some missing standard functions, we re-implement them here

@@ -86,7 +93,7 @@ impl Lua {
        }

        // Enable default `require` implementation
-        let require = self.create_require_function(require::TextRequirer::new())?;
+        let require = self.create_require_function(FsRequirer::new())?;
        self.globals().raw_set("require", require)?;

        Ok(())
@@ -8,12 +8,11 @@ use std::{fmt, mem, ptr};

 use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::state::{callback_error_ext, Lua};
+use crate::state::{Lua, callback_error_ext};
 use crate::table::Table;
 use crate::types::MaybeSend;

-// TODO: Rename to FsRequirer
-pub use fs::TextRequirer;
+pub use fs::FsRequirer;

 /// An error that can occur during navigation in the Luau `require-by-string` system.
 #[derive(Debug, Clone)]
@@ -12,7 +12,7 @@ use super::{NavigateError, Require};

 /// The standard implementation of Luau `require-by-string` navigation.
 #[derive(Default, Debug)]
-pub struct TextRequirer {
+pub struct FsRequirer {
    /// 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)
@@ -22,7 +22,7 @@ pub struct TextRequirer {
    resolved_path: Option<PathBuf>,
 }

-impl TextRequirer {
+impl FsRequirer {
    /// 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 = "@";
@@ -36,16 +36,16 @@ impl TextRequirer {
    /// The filename for the Luau configuration file.
    const LUAU_CONFIG_FILENAME: &str = ".config.luau";

-    /// Creates a new `TextRequirer` instance.
+    /// Creates a new `FsRequirer` 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;
-            }
+        if let Some((path, line)) = chunk_name.rsplit_once(':')
+            && line.parse::<u32>().is_ok()
+        {
+            return path;
        }
        chunk_name
    }
@@ -114,7 +114,7 @@ impl TextRequirer {
    }
 }

-impl Require for TextRequirer {
+impl Require for FsRequirer {
    fn is_require_allowed(&self, chunk_name: &str) -> bool {
        chunk_name.starts_with(Self::CHUNK_PREFIX)
    }
@@ -231,7 +231,7 @@ impl Require for TextRequirer {
 mod tests {
    use std::path::Path;

-    use super::TextRequirer;
+    use super::FsRequirer;

    #[test]
    fn test_path_normalize() {
@@ -267,7 +267,7 @@ mod tests {
            // '..' disappears if path is absolute and component is non-erasable
            ("/../", "/"),
        ] {
-            let path = TextRequirer::normalize_path(input.as_ref());
+            let path = FsRequirer::normalize_path(input.as_ref());
            assert_eq!(
                &path,
                expected.as_ref() as &Path,
@@ -28,9 +28,7 @@ impl MemoryState {
    }

    #[cfg(not(feature = "luau"))]
-    #[rustversion::since(1.85)]
    #[inline]
-    #[allow(clippy::incompatible_msrv)]
    pub(crate) unsafe fn get(state: *mut ffi::lua_State) -> *mut Self {
        let mut mem_state = ptr::null_mut();
        if !ptr::fn_addr_eq(ffi::lua_getallocf(state, &mut mem_state), ALLOCATOR) {
@@ -39,17 +37,6 @@ impl MemoryState {
        mem_state as *mut MemoryState
    }

-    #[cfg(not(feature = "luau"))]
-    #[rustversion::before(1.85)]
-    #[inline]
-    pub(crate) unsafe fn get(state: *mut ffi::lua_State) -> *mut Self {
-        let mut mem_state = ptr::null_mut();
-        if ffi::lua_getallocf(state, &mut mem_state) != ALLOCATOR {
-            mem_state = ptr::null_mut();
-        }
-        mem_state as *mut MemoryState
-    }
-
    #[inline]
    pub(crate) fn used_memory(&self) -> usize {
        self.used_memory as usize
@@ -1,4 +1,4 @@
-use std::collections::{vec_deque, VecDeque};
+use std::collections::{VecDeque, vec_deque};
 use std::iter::FromIterator;
 use std::mem;
 use std::ops::{Deref, DerefMut};
@@ -3,35 +3,44 @@
 #[doc(no_inline)]
 pub use crate::{
    AnyUserData as LuaAnyUserData, BorrowedBytes as LuaBorrowedBytes, BorrowedStr as LuaBorrowedStr,
-    Chunk as LuaChunk, Either as LuaEither, Error as LuaError, ErrorContext as LuaErrorContext,
-    ExternalError as LuaExternalError, ExternalResult as LuaExternalResult, FromLua, FromLuaMulti,
-    Function as LuaFunction, FunctionInfo as LuaFunctionInfo, GCMode as LuaGCMode, Integer as LuaInteger,
-    IntoLua, IntoLuaMulti, LightUserData as LuaLightUserData, Lua, LuaNativeFn, LuaNativeFnMut, LuaOptions,
-    MetaMethod as LuaMetaMethod, MultiValue as LuaMultiValue, Nil as LuaNil, Number as LuaNumber,
+    Either as LuaEither, Error as LuaError, FromLua, FromLuaMulti, Function as LuaFunction,
+    Integer as LuaInteger, IntoLua, IntoLuaMulti, LightUserData as LuaLightUserData, Lua, LuaOptions,
+    LuaString, MetaMethod as LuaMetaMethod, MultiValue as LuaMultiValue, Nil as LuaNil, Number as LuaNumber,
    ObjectLike as LuaObjectLike, RegistryKey as LuaRegistryKey, Result as LuaResult, StdLib as LuaStdLib,
-    String as LuaString, Table as LuaTable, TablePairs as LuaTablePairs, TableSequence as LuaTableSequence,
-    Thread as LuaThread, ThreadStatus as LuaThreadStatus, UserData as LuaUserData,
-    UserDataFields as LuaUserDataFields, UserDataMetatable as LuaUserDataMetatable,
-    UserDataMethods as LuaUserDataMethods, UserDataRef as LuaUserDataRef,
-    UserDataRefMut as LuaUserDataRefMut, UserDataRegistry as LuaUserDataRegistry, Value as LuaValue,
-    Variadic as LuaVariadic, VmState as LuaVmState, WeakLua,
+    Table as LuaTable, Thread as LuaThread, UserData as LuaUserData, UserDataFields as LuaUserDataFields,
+    UserDataMetatable as LuaUserDataMetatable, UserDataMethods as LuaUserDataMethods,
+    UserDataOwned as LuaUserDataOwned, UserDataRef as LuaUserDataRef, UserDataRefMut as LuaUserDataRefMut,
+    UserDataRegistry as LuaUserDataRegistry, Value as LuaValue, Variadic as LuaVariadic,
+    VmState as LuaVmState, WeakLua, chunk::AsChunk as AsLuaChunk, chunk::Chunk as LuaChunk,
+    chunk::ChunkMode as LuaChunkMode, error::ErrorContext as LuaErrorContext,
+    error::ExternalError as LuaExternalError, error::ExternalResult as LuaExternalResult,
+    function::FunctionInfo as LuaFunctionInfo, function::LuaNativeFn, function::LuaNativeFnMut,
+    state::GcIncParams as LuaGcIncParams, state::GcMode as LuaGcMode, table::TablePairs as LuaTablePairs,
+    table::TableSequence as LuaTableSequence, thread::ThreadStatus as LuaThreadStatus,
 };

 #[cfg(not(feature = "luau"))]
 #[doc(no_inline)]
 pub use crate::HookTriggers as LuaHookTriggers;

+#[cfg(any(feature = "lua54", feature = "lua55"))]
+#[doc(no_inline)]
+pub use crate::state::GcGenParams as LuaGcGenParams;
+
 #[cfg(feature = "luau")]
 #[doc(no_inline)]
 pub use crate::{
-    CompileConstant as LuaCompileConstant, CoverageInfo as LuaCoverageInfo,
-    NavigateError as LuaNavigateError, Require as LuaRequire, TextRequirer as LuaTextRequirer,
    Vector as LuaVector,
+    chunk::{CompileConstant as LuaCompileConstant, Compiler as LuaCompiler},
+    luau::{
+        FsRequirer as LuaFsRequirer, HeapDump as LuaHeapDump, NavigateError as LuaNavigateError,
+        Require as LuaRequire,
+    },
 };

 #[cfg(feature = "async")]
 #[doc(no_inline)]
-pub use crate::{AsyncThread as LuaAsyncThread, LuaNativeAsyncFn};
+pub use crate::{function::LuaNativeAsyncFn, thread::AsyncThread as LuaAsyncThread};

 #[cfg(feature = "serde")]
 #[doc(no_inline)]
@@ -8,7 +8,7 @@ use crate::state::{Lua, LuaGuard, RawLua};
 use crate::traits::{FromLuaMulti, IntoLuaMulti};
 use crate::types::{Callback, CallbackUpvalue, ScopedCallback, ValueRef};
 use crate::userdata::{AnyUserData, UserData, UserDataRegistry, UserDataStorage};
-use crate::util::{self, check_stack, get_metatable_ptr, get_userdata, take_userdata, StackGuard};
+use crate::util::{self, StackGuard, check_stack, get_metatable_ptr, get_userdata, take_userdata};

 /// Constructed by the [`Lua::scope`] method, allows temporarily creating Lua userdata and
 /// callbacks that are not required to be `Send` or `'static`.
@@ -4,7 +4,6 @@ use std::cell::RefCell;
 use std::os::raw::c_void;
 use std::rc::Rc;
 use std::result::Result as StdResult;
-use std::string::String as StdString;

 use rustc_hash::FxHashSet;
 use serde::de::{self, IntoDeserializer};
@@ -243,14 +242,14 @@ impl<'de> serde::Deserializer<'de> for Deserializer {
            Value::Table(table) => {
                let _guard = RecursionGuard::new(&table, &self.visited);

-                let mut iter = table.pairs::<StdString, Value>();
+                let mut iter = table.pairs::<String, Value>();
                let (variant, value) = match iter.next() {
                    Some(v) => v?,
                    None => {
                        return Err(de::Error::invalid_value(
                            de::Unexpected::Map,
                            &"map with a single key",
-                        ))
+                        ));
                    }
                };

@@ -621,7 +620,7 @@ impl<'de> de::MapAccess<'de> for MapDeserializer<'_> {
 }

 struct EnumDeserializer {
-    variant: StdString,
+    variant: String,
    value: Option<Value>,
    options: Options,
    visited: Rc<RefCell<FxHashSet<*const c_void>>>,
@@ -37,8 +37,8 @@ pub trait LuaSerdeExt: Sealed {
    fn null(&self) -> Value;

    /// A metatable attachable to a Lua table to systematically encode it as Array (instead of Map).
-    /// As result, encoded Array will contain only sequence part of the table, with the same length
-    /// as the `#` operator on that table.
+    /// As a result, encoded Array will contain only sequence part of the table, with the same
+    /// length as the `#` operator on that table.
    ///
    /// # Example
    ///
@@ -242,7 +242,5 @@ static ARRAY_METATABLE_REGISTRY_KEY: u8 = 0;
 pub mod de;
 pub mod ser;

-#[doc(inline)]
-pub use de::Deserializer;
-#[doc(inline)]
-pub use ser::Serializer;
+pub use de::{Deserializer, Options as DeserializeOptions};
+pub use ser::{Options as SerializeOptions, Serializer};
@@ -1,6 +1,6 @@
 //! Serialize a Rust data structure into Lua value.

-use serde::{ser, Serialize};
+use serde::{Serialize, ser};

 use super::LuaSerdeExt;
 use crate::error::{Error, Result};
@@ -531,10 +531,10 @@ impl ser::SerializeStruct for SerializeStruct<'_> {
            Some(table @ Value::Table(_)) => Ok(table),
            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);
-                    }
+                if number_s.contains(['.', 'e', 'E'])
+                    && let Ok(number) = number_s.parse().map(Value::Number)
+                {
+                    return Ok(number);
                }
                Ok(number_s
                    .parse()
@@ -1,3 +1,8 @@
+//! Lua state management.
+//!
+//! This module provides the main [`Lua`] state handle together with state-specific
+//! configuration and garbage collector controls.
+
 use std::any::TypeId;
 use std::cell::{BorrowError, BorrowMutError, RefCell};
 use std::marker::PhantomData;
@@ -15,16 +20,16 @@ use crate::memory::MemoryState;
 use crate::multi::MultiValue;
 use crate::scope::Scope;
 use crate::stdlib::StdLib;
-use crate::string::String;
+use crate::string::LuaString;
 use crate::table::Table;
 use crate::thread::Thread;
 use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti};
 use crate::types::{
-    AppDataRef, AppDataRefMut, ArcReentrantMutexGuard, Integer, LuaType, MaybeSend, Number, ReentrantMutex,
-    ReentrantMutexGuard, RegistryKey, VmState, XRc, XWeak,
+    AppDataRef, AppDataRefMut, ArcReentrantMutexGuard, Integer, LuaType, MaybeSend, MaybeSync, Number,
+    ReentrantMutex, ReentrantMutexGuard, RegistryKey, VmState, XRc, XWeak,
 };
 use crate::userdata::{AnyUserData, UserData, UserDataProxy, UserDataRegistry, UserDataStorage};
-use crate::util::{assert_stack, check_stack, protect_lua_closure, push_string, rawset_field, StackGuard};
+use crate::util::{StackGuard, assert_stack, check_stack, protect_lua_closure, push_string, rawset_field};
 use crate::value::{Nil, Value};

 #[cfg(not(feature = "luau"))]
@@ -44,6 +49,7 @@ use {
 use serde::Serialize;

 pub(crate) use extra::ExtraData;
+#[doc(hidden)]
 pub use raw::RawLua;
 pub(crate) use util::callback_error_ext;

@@ -62,20 +68,126 @@ pub struct WeakLua(XWeak<ReentrantMutex<RawLua>>);

 pub(crate) struct LuaGuard(ArcReentrantMutexGuard<RawLua>);

-/// Mode of the Lua garbage collector (GC).
-///
-/// In Lua 5.4 GC can work in two modes: incremental and generational.
-/// Previous Lua versions support only incremental GC.
+/// Tuning parameters for the incremental GC collector.
 ///
 /// More information can be found in the Lua [documentation].
 ///
-/// [documentation]: https://www.lua.org/manual/5.4/manual.html#2.5
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum GCMode {
-    Incremental,
+/// [documentation]: https://www.lua.org/manual/5.5/manual.html#2.5.1
+#[non_exhaustive]
+#[derive(Clone, Copy, Debug, Default)]
+pub struct GcIncParams {
+    /// Pause between successive GC cycles, expressed as a percentage of live memory.
+    #[cfg(not(feature = "luau"))]
+    #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
+    pub pause: Option<c_int>,
+
+    /// Target heap size as a percentage of live data, controlling how aggressively
+    /// the GC reclaims memory (`LUA_GCSETGOAL`).
+    #[cfg(any(feature = "luau", doc))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub goal: Option<c_int>,
+
+    /// GC work performed per unit of memory allocated.
+    pub step_multiplier: Option<c_int>,
+
+    /// Granularity of each GC step (see Lua reference for details).
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "luau"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54", feature = "luau"))))]
+    pub step_size: Option<c_int>,
+}
+
+impl GcIncParams {
+    /// Sets the `pause` parameter.
+    #[cfg(not(feature = "luau"))]
+    #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
+    pub fn pause(mut self, v: c_int) -> Self {
+        self.pause = Some(v);
+        self
+    }
+
+    /// Sets the `goal` parameter.
+    #[cfg(any(feature = "luau", doc))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub fn goal(mut self, v: c_int) -> Self {
+        self.goal = Some(v);
+        self
+    }
+
+    /// Sets the `step_multiplier` parameter.
+    pub fn step_multiplier(mut self, v: c_int) -> Self {
+        self.step_multiplier = Some(v);
+        self
+    }
+
+    /// Sets the `step_size` parameter.
+    #[cfg(any(feature = "lua55", feature = "lua54", feature = "luau"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54", feature = "luau"))))]
+    pub fn step_size(mut self, v: c_int) -> Self {
+        self.step_size = Some(v);
+        self
+    }
+}
+
+/// Tuning parameters for the generational GC collector (Lua 5.4+).
+///
+/// More information can be found in the Lua [documentation].
+///
+/// [documentation]: https://www.lua.org/manual/5.5/manual.html#2.5.2
+#[cfg(any(feature = "lua55", feature = "lua54"))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
+#[non_exhaustive]
+#[derive(Clone, Copy, Debug, Default)]
+pub struct GcGenParams {
+    /// Frequency of minor (young-generation) collection steps.
+    pub minor_multiplier: Option<c_int>,
+
+    /// Threshold controlling how large the young generation can grow before triggering
+    /// a shift from minor to major collection.
+    pub minor_to_major: Option<c_int>,
+
+    /// Threshold controlling how much the major collection must shrink the heap before
+    /// switching back to minor (young-generation) collection.
+    #[cfg(feature = "lua55")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "lua55")))]
+    pub major_to_minor: Option<c_int>,
+}
+
+#[cfg(any(feature = "lua55", feature = "lua54"))]
+impl GcGenParams {
+    /// Sets the `minor_multiplier` parameter.
+    pub fn minor_multiplier(mut self, v: c_int) -> Self {
+        self.minor_multiplier = Some(v);
+        self
+    }
+
+    /// Sets the `minor_to_major` threshold.
+    pub fn minor_to_major(mut self, v: c_int) -> Self {
+        self.minor_to_major = Some(v);
+        self
+    }
+
+    /// Sets the `major_to_minor` parameter.
+    #[cfg(feature = "lua55")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "lua55")))]
+    pub fn major_to_minor(mut self, v: c_int) -> Self {
+        self.major_to_minor = Some(v);
+        self
+    }
+}
+
+/// Lua garbage collector (GC) operating mode.
+///
+/// Use [`Lua::gc_set_mode`] to switch the collector mode and/or tune its parameters.
+#[non_exhaustive]
+#[derive(Clone, Debug)]
+pub enum GcMode {
+    /// Incremental mark-and-sweep
+    Incremental(GcIncParams),
+
+    /// Generational
    #[cfg(any(feature = "lua55", feature = "lua54"))]
    #[cfg_attr(docsrs, doc(cfg(any(feature = "lua55", feature = "lua54"))))]
-    Generational,
+    Generational(GcGenParams),
 }

 /// Controls Lua interpreter behavior such as Rust panics handling.
@@ -337,30 +449,27 @@ 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.
+    /// Calls provided function passing a reference to the [`RawLua`] handle.
    ///
-    /// This function is safe because all unsafe actions with RawLua can only be done with unsafe
+    /// Provided [`RawLua`] handle can be used to manually pushing/popping values to/from the stack.
    ///
    /// # Example
    /// ```
-    /// # use mlua::{Lua, Result, FromLua, IntoLua};
+    /// # use mlua::{Lua, Result, FromLua, IntoLua, IntoLuaMulti};
    /// # 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 nums = (3, 4, 5);
+    ///     lua.exec_raw_lua(|rawlua| unsafe {
+    ///         nums.push_into_stack_multi(rawlua)?;
+    ///         let mut sum = 0;
+    ///         for _ in 0..3 {
+    ///             sum += rawlua.pop::<i32>()?;
    ///         }
-    ///
-    ///         let n = unsafe {
-    ///             <i32 as FromLua>::from_stack(-1, lua)?
-    ///         };
-    ///         Result::Ok(n)
+    ///         Result::Ok(sum)
    ///     })
    /// }?;
-    /// assert_eq!(n, 11);
+    /// assert_eq!(n, 12);
    /// # Ok(())
    /// # }
    /// ```
@@ -437,31 +546,6 @@ impl Lua {
        Ok(())
    }

-    #[doc(hidden)]
-    #[deprecated(since = "0.11.0", note = "Use `register_module` instead")]
-    #[cfg(not(feature = "luau"))]
-    #[cfg(not(tarpaulin_include))]
-    pub fn load_from_function<T: FromLua>(&self, modname: &str, func: Function) -> Result<T> {
-        let loaded = unsafe {
-            self.exec_raw::<Table>((), |state| {
-                ffi::luaL_getsubtable(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_LOADED_TABLE);
-            })?
-        };
-
-        let value = match loaded.raw_get(modname)? {
-            Value::Nil => {
-                let result = match func.call(modname)? {
-                    Value::Nil => Value::Boolean(true),
-                    res => res,
-                };
-                loaded.raw_set(modname, &result)?;
-                result
-            }
-            res => res,
-        };
-        T::from_lua(value, self)
-    }
-
    /// Unloads module `modname`.
    ///
    /// This method does not support unloading binary Lua modules since they are internally cached
@@ -855,7 +939,6 @@ impl Lua {
    {
        use std::ffi::CStr;
        use std::os::raw::{c_char, c_void};
-        use std::string::String as StdString;

        unsafe extern "C-unwind" fn warn_proc(ud: *mut c_void, msg: *const c_char, tocont: c_int) {
            let extra = ud as *mut ExtraData;
@@ -865,7 +948,7 @@ impl Lua {
                if XRc::strong_count(&warn_callback) > 2 {
                    return Ok(());
                }
-                let msg = StdString::from_utf8_lossy(CStr::from_ptr(msg).to_bytes());
+                let msg = String::from_utf8_lossy(CStr::from_ptr(msg).to_bytes());
                warn_callback((*extra).lua(), &msg, tocont != 0)
            });
        }
@@ -910,8 +993,8 @@ impl Lua {

    /// Gets information about the interpreter runtime stack at the given level.
    ///
-    /// This function calls callback `f`, passing the [`Debug`] structure that can be used to get
-    /// information about the function executing at a given level.
+    /// This function calls callback `f`, passing the [`struct@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> {
@@ -936,7 +1019,7 @@ impl Lua {
    ///
    /// 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> {
+    pub fn traceback(&self, msg: Option<&str>, level: usize) -> Result<LuaString> {
        let lua = self.lock();
        unsafe {
            check_stack(lua.state(), 3)?;
@@ -948,7 +1031,7 @@ impl Lua {
                // `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()))
+            Ok(LuaString(lua.pop_ref()))
        }
    }

@@ -999,19 +1082,19 @@ impl Lua {
        unsafe { ffi::lua_gc(lua.main_state(), ffi::LUA_GCISRUNNING, 0) != 0 }
    }

-    /// Stop the Lua GC from running
+    /// Stops the Lua GC from running.
    pub fn gc_stop(&self) {
        let lua = self.lock();
        unsafe { ffi::lua_gc(lua.main_state(), ffi::LUA_GCSTOP, 0) };
    }

-    /// Restarts the Lua GC if it is not running
+    /// Restarts the Lua GC if it is not running.
    pub fn gc_restart(&self) {
        let lua = self.lock();
        unsafe { ffi::lua_gc(lua.main_state(), ffi::LUA_GCRESTART, 0) };
    }

-    /// Perform a full garbage-collection cycle.
+    /// Performs a full garbage-collection cycle.
    ///
    /// It may be necessary to call this function twice to collect all currently unreachable
    /// objects. Once to finish the current gc cycle, and once to start and finish the next cycle.
@@ -1024,153 +1107,128 @@ impl Lua {
        }
    }

-    /// Steps the garbage collector one indivisible step.
+    /// Performs a basic step of garbage collection.
    ///
-    /// Returns `true` if this has finished a collection cycle.
+    /// In incremental mode, a basic step corresponds to the current step size. In generational
+    /// mode, a basic step performs a full minor collection or an incremental step, if the collector
+    /// has scheduled one.
+    ///
+    /// In incremental mode, returns `true` if this step has finished a collection cycle.
+    /// In generational mode, returns `true` if the step finished a major collection.
    pub fn gc_step(&self) -> Result<bool> {
-        self.gc_step_kbytes(0)
-    }
-
-    /// Steps the garbage collector as though memory had been allocated.
-    ///
-    /// if `kbytes` is 0, then this is the same as calling `gc_step`. Returns true if this step has
-    /// finished a collection cycle.
-    pub fn gc_step_kbytes(&self, kbytes: c_int) -> Result<bool> {
        let lua = self.lock();
        let state = lua.main_state();
        unsafe {
            check_stack(state, 3)?;
            protect_lua!(state, 0, 0, |state| {
-                ffi::lua_gc(state, ffi::LUA_GCSTEP, kbytes) != 0
+                ffi::lua_gc(state, ffi::LUA_GCSTEP, 0) != 0
            })
        }
    }

-    /// Sets the `pause` value of the collector.
+    /// Switches the GC to the given mode with the provided parameters.
    ///
-    /// Returns the previous value of `pause`. More information can be found in the Lua
-    /// [documentation].
+    /// Returns the previous [`GcMode`]. The returned value's parameter fields are always
+    /// `None` because Lua's C API does not provide a way to read back current parameter values
+    /// without changing them.
    ///
-    /// For Luau this parameter sets GC goal
+    /// # Examples
    ///
-    /// [documentation]: https://www.lua.org/manual/5.4/manual.html#2.5
-    pub fn gc_set_pause(&self, pause: c_int) -> c_int {
+    /// Switch to generational mode (Lua 5.4+):
+    /// ```ignore
+    /// let prev = lua.gc_set_mode(GcMode::Generational(GcGenParams::default()));
+    /// ```
+    ///
+    /// Switch to incremental mode with custom parameters:
+    /// ```ignore
+    /// lua.gc_set_mode(GcMode::Incremental(
+    ///     GcIncParams::default().pause(200).step_multiplier(100)
+    /// ));
+    /// ```
+    pub fn gc_set_mode(&self, mode: GcMode) -> GcMode {
        let lua = self.lock();
        let state = lua.main_state();
-        unsafe {
+
+        match mode {
            #[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);
-
+            GcMode::Incremental(params) => unsafe {
+                if let Some(v) = params.pause {
+                    ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPPAUSE, v);
+                }
+                if let Some(v) = params.step_multiplier {
+                    ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPSTEPMUL, v);
+                }
+                if let Some(v) = params.step_size {
+                    ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPSTEPSIZE, v);
+                }
+                match ffi::lua_gc(state, ffi::LUA_GCINC) {
+                    ffi::LUA_GCINC => GcMode::Incremental(GcIncParams::default()),
+                    ffi::LUA_GCGEN => GcMode::Generational(GcGenParams::default()),
+                    _ => unreachable!(),
+                }
+            },
+            #[cfg(feature = "lua54")]
+            GcMode::Incremental(params) => unsafe {
+                let pause = params.pause.unwrap_or(0);
+                let step_mul = params.step_multiplier.unwrap_or(0);
+                let step_size = params.step_size.unwrap_or(0);
+                match ffi::lua_gc(state, ffi::LUA_GCINC, pause, step_mul, step_size) {
+                    ffi::LUA_GCINC => GcMode::Incremental(GcIncParams::default()),
+                    ffi::LUA_GCGEN => GcMode::Generational(GcGenParams::default()),
+                    _ => unreachable!(),
+                }
+            },
+            #[cfg(any(feature = "lua53", feature = "lua52", feature = "lua51", feature = "luajit"))]
+            GcMode::Incremental(params) => unsafe {
+                if let Some(v) = params.pause {
+                    ffi::lua_gc(state, ffi::LUA_GCSETPAUSE, v);
+                }
+                if let Some(v) = params.step_multiplier {
+                    ffi::lua_gc(state, ffi::LUA_GCSETSTEPMUL, v);
+                }
+                GcMode::Incremental(GcIncParams::default())
+            },
            #[cfg(feature = "luau")]
-            return ffi::lua_gc(state, ffi::LUA_GCSETGOAL, pause);
-        }
-    }
+            GcMode::Incremental(params) => unsafe {
+                if let Some(v) = params.goal {
+                    ffi::lua_gc(state, ffi::LUA_GCSETGOAL, v);
+                }
+                if let Some(v) = params.step_multiplier {
+                    ffi::lua_gc(state, ffi::LUA_GCSETSTEPMUL, v);
+                }
+                if let Some(v) = params.step_size {
+                    ffi::lua_gc(state, ffi::LUA_GCSETSTEPSIZE, v);
+                }
+                GcMode::Incremental(GcIncParams::default())
+            },

-    /// Sets the `step multiplier` value of the collector.
-    ///
-    /// Returns the previous value of the `step multiplier`. More information can be found in the
-    /// Lua [documentation].
-    ///
-    /// [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 {
            #[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.
-    ///
-    /// Returns the previous mode (always `GCMode::Incremental` in Lua < 5.4).
-    /// More information can be found in the Lua [documentation].
-    ///
-    /// [documentation]: https://www.lua.org/manual/5.4/manual.html#2.5.1
-    pub fn gc_inc(&self, pause: c_int, step_multiplier: c_int, step_size: c_int) -> GCMode {
-        let lua = self.lock();
-        let state = lua.main_state();
-
-        #[cfg(any(
-            feature = "lua53",
-            feature = "lua52",
-            feature = "lua51",
-            feature = "luajit",
-            feature = "luau"
-        ))]
-        unsafe {
-            if pause > 0 {
-                #[cfg(not(feature = "luau"))]
-                ffi::lua_gc(state, ffi::LUA_GCSETPAUSE, pause);
-                #[cfg(feature = "luau")]
-                ffi::lua_gc(state, ffi::LUA_GCSETGOAL, pause);
-            }
-
-            if step_multiplier > 0 {
-                ffi::lua_gc(state, ffi::LUA_GCSETSTEPMUL, step_multiplier);
-            }
-
-            #[cfg(feature = "luau")]
-            if step_size > 0 {
-                ffi::lua_gc(state, ffi::LUA_GCSETSTEPSIZE, step_size);
-            }
-            #[cfg(not(feature = "luau"))]
-            let _ = step_size; // Ignored
-
-            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(any(feature = "lua55", feature = "lua54"))]
-        match prev_mode {
-            ffi::LUA_GCINC => GCMode::Incremental,
-            ffi::LUA_GCGEN => GCMode::Generational,
-            _ => unreachable!(),
-        }
-    }
-
-    /// Changes the collector to generational mode with the given parameters.
-    ///
-    /// Returns the previous mode. More information about the generational GC
-    /// 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(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,
-            ffi::LUA_GCINC => GCMode::Incremental,
-            _ => unreachable!(),
+            GcMode::Generational(params) => unsafe {
+                if let Some(v) = params.minor_multiplier {
+                    ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPMINORMUL, v);
+                }
+                if let Some(v) = params.minor_to_major {
+                    ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPMINORMAJOR, v);
+                }
+                if let Some(v) = params.major_to_minor {
+                    ffi::lua_gc(state, ffi::LUA_GCPARAM, ffi::LUA_GCPMAJORMINOR, v);
+                }
+                match ffi::lua_gc(state, ffi::LUA_GCGEN) {
+                    ffi::LUA_GCGEN => GcMode::Generational(GcGenParams::default()),
+                    ffi::LUA_GCINC => GcMode::Incremental(GcIncParams::default()),
+                    _ => unreachable!(),
+                }
+            },
+            #[cfg(feature = "lua54")]
+            GcMode::Generational(params) => unsafe {
+                let minor = params.minor_multiplier.unwrap_or(0);
+                let minor_to_major = params.minor_to_major.unwrap_or(0);
+                match ffi::lua_gc(state, ffi::LUA_GCGEN, minor, minor_to_major) {
+                    ffi::LUA_GCGEN => GcMode::Generational(GcGenParams::default()),
+                    ffi::LUA_GCINC => GcMode::Incremental(GcIncParams::default()),
+                    _ => unreachable!(),
+                }
+            },
        }
    }

@@ -1205,10 +1263,10 @@ impl Lua {
    #[doc(hidden)]
    #[allow(clippy::result_unit_err)]
    pub fn set_fflag(name: &str, enabled: bool) -> StdResult<(), ()> {
-        if let Ok(name) = std::ffi::CString::new(name) {
-            if unsafe { ffi::luau_setfflag(name.as_ptr(), enabled as c_int) != 0 } {
-                return Ok(());
-            }
+        if let Ok(name) = std::ffi::CString::new(name)
+            && unsafe { ffi::luau_setfflag(name.as_ptr(), enabled as c_int) != 0 }
+        {
+            return Ok(());
        }
        Err(())
    }
@@ -1248,7 +1306,7 @@ impl Lua {
    /// 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> {
+    pub fn create_string(&self, s: impl AsRef<[u8]>) -> Result<LuaString> {
        unsafe { self.lock().create_string(s.as_ref()) }
    }

@@ -1259,7 +1317,7 @@ impl Lua {
    #[cfg(feature = "lua55")]
    #[cfg_attr(docsrs, doc(cfg(feature = "lua55")))]
    #[inline]
-    pub fn create_external_string(&self, s: impl Into<Vec<u8>>) -> Result<String> {
+    pub fn create_external_string(&self, s: impl Into<Vec<u8>>) -> Result<LuaString> {
        unsafe { self.lock().create_external_string(s.into()) }
    }

@@ -1457,7 +1515,7 @@ impl Lua {
    /// }
    /// ```
    ///
-    /// [`AsyncThread`]: crate::AsyncThread
+    /// [`AsyncThread`]: crate::thread::AsyncThread
    #[cfg(feature = "async")]
    #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
    pub fn create_async_function<F, A, FR, R>(&self, func: F) -> Result<Function>
@@ -1493,7 +1551,7 @@ impl Lua {
    #[inline]
    pub fn create_userdata<T>(&self, data: T) -> Result<AnyUserData>
    where
-        T: UserData + MaybeSend + 'static,
+        T: UserData + MaybeSend + MaybeSync + 'static,
    {
        unsafe { self.lock().make_userdata(UserDataStorage::new(data)) }
    }
@@ -1504,7 +1562,7 @@ impl Lua {
    #[inline]
    pub fn create_ser_userdata<T>(&self, data: T) -> Result<AnyUserData>
    where
-        T: UserData + Serialize + MaybeSend + 'static,
+        T: UserData + Serialize + MaybeSend + MaybeSync + 'static,
    {
        unsafe { self.lock().make_userdata(UserDataStorage::new_ser(data)) }
    }
@@ -1519,7 +1577,7 @@ impl Lua {
    #[inline]
    pub fn create_any_userdata<T>(&self, data: T) -> Result<AnyUserData>
    where
-        T: MaybeSend + 'static,
+        T: MaybeSend + MaybeSync + 'static,
    {
        unsafe { self.lock().make_any_userdata(UserDataStorage::new(data)) }
    }
@@ -1532,7 +1590,7 @@ impl Lua {
    #[inline]
    pub fn create_ser_any_userdata<T>(&self, data: T) -> Result<AnyUserData>
    where
-        T: Serialize + MaybeSend + 'static,
+        T: Serialize + MaybeSend + MaybeSync + 'static,
    {
        unsafe { (self.lock()).make_any_userdata(UserDataStorage::new_ser(data)) }
    }
@@ -1741,7 +1799,7 @@ impl Lua {
    ///
    /// To succeed, the value must be a string (in which case this is a no-op), an integer, or a
    /// number.
-    pub fn coerce_string(&self, v: Value) -> Result<Option<String>> {
+    pub fn coerce_string(&self, v: Value) -> Result<Option<LuaString>> {
        Ok(match v {
            Value::String(s) => Some(s),
            v => unsafe {
@@ -1759,7 +1817,7 @@ impl Lua {
                    })?
                };
                if !res.is_null() {
-                    Some(String(lua.pop_ref()))
+                    Some(LuaString(lua.pop_ref()))
                } else {
                    None
                }
@@ -1785,11 +1843,7 @@ impl Lua {
                lua.push_value(&v)?;
                let mut isint = 0;
                let i = ffi::lua_tointegerx(state, -1, &mut isint);
-                if isint == 0 {
-                    None
-                } else {
-                    Some(i)
-                }
+                if isint == 0 { None } else { Some(i) }
            },
        })
    }
@@ -1811,11 +1865,7 @@ impl Lua {
                lua.push_value(&v)?;
                let mut isnum = 0;
                let n = ffi::lua_tonumberx(state, -1, &mut isnum);
-                if isnum == 0 {
-                    None
-                } else {
-                    Some(n)
-                }
+                if isnum == 0 { None } else { Some(n) }
            },
        })
    }
@@ -14,7 +14,7 @@ use crate::state::RawLua;
 use crate::stdlib::StdLib;
 use crate::types::{AppData, ReentrantMutex, XRc};
 use crate::userdata::RawUserDataRegistry;
-use crate::util::{get_internal_metatable, push_internal_userdata, TypeKey, WrappedFailure};
+use crate::util::{TypeKey, WrappedFailure, get_internal_metatable, push_internal_userdata};

 #[cfg(any(feature = "luau", doc))]
 use crate::chunk::Compiler;
@@ -10,26 +10,26 @@ use std::sync::Arc;
 use crate::chunk::ChunkMode;
 use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::memory::{MemoryState, ALLOCATOR};
+use crate::memory::{ALLOCATOR, MemoryState};
 use crate::state::util::callback_error_ext;
 use crate::stdlib::StdLib;
-use crate::string::String;
+use crate::string::LuaString;
 use crate::table::Table;
 use crate::thread::Thread;
-use crate::traits::IntoLua;
+use crate::traits::{FromLua, IntoLua};
 use crate::types::{
    AppDataRef, AppDataRefMut, Callback, CallbackUpvalue, DestructedUserdata, Integer, LightUserData,
    LuaType, MaybeSend, ReentrantMutex, RegistryKey, ValueRef, XRc,
 };
 use crate::userdata::{
-    init_userdata_metatable, AnyUserData, MetaMethod, RawUserDataRegistry, UserData, UserDataRegistry,
-    UserDataStorage,
+    AnyUserData, MetaMethod, RawUserDataRegistry, UserData, UserDataRegistry, UserDataStorage,
+    init_userdata_metatable,
 };
 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, push_userdata, rawset_field, safe_pcall, safe_xpcall,
-    short_type_name, StackGuard, WrappedFailure,
+    StackGuard, WrappedFailure, 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, push_userdata,
+    rawset_field, safe_pcall, safe_xpcall, short_type_name,
 };
 use crate::value::{Nil, Value};

@@ -50,7 +50,7 @@ use {
    std::task::{Context, Poll, Waker},
 };

-/// An inner Lua struct which holds a raw Lua state.
+/// An internal Lua struct which holds a raw Lua state.
 #[doc(hidden)]
 pub struct RawLua {
    // The state is dynamic and depends on context
@@ -516,34 +516,34 @@ impl RawLua {
    }

    /// See [`Lua::create_string`]
-    pub(crate) unsafe fn create_string(&self, s: &[u8]) -> Result<String> {
+    pub(crate) unsafe fn create_string(&self, s: &[u8]) -> Result<LuaString> {
        let state = self.state();
        if self.unlikely_memory_error() {
            push_string(state, s, false)?;
-            return Ok(String(self.pop_ref()));
+            return Ok(LuaString(self.pop_ref()));
        }

        let _sg = StackGuard::new(state);
        check_stack(state, 3)?;
        push_string(state, s, true)?;
-        Ok(String(self.pop_ref()))
+        Ok(LuaString(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> {
+    pub(crate) unsafe fn create_external_string(&self, bytes: Vec<u8>) -> Result<LuaString> {
        let state = self.state();
        if self.unlikely_memory_error() {
            crate::util::push_external_string(state, bytes, false)?;
-            return Ok(String(self.pop_ref()));
+            return Ok(LuaString(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()))
+        Ok(LuaString(self.pop_ref()))
    }

    #[cfg(feature = "luau")]
@@ -681,10 +681,10 @@ impl RawLua {
    #[cfg(feature = "async")]
    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() {
-            if let Some(index) = thread.0.index_count.take() {
-                extra.thread_pool.push(index);
-            }
+        if extra.thread_pool.len() < extra.thread_pool.capacity()
+            && let Some(index) = thread.0.index_count.take()
+        {
+            extra.thread_pool.push(index);
        }
    }

@@ -731,14 +731,27 @@ impl RawLua {
    /// 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`.
+    #[allow(clippy::missing_safety_doc)]
    #[inline(always)]
    pub unsafe fn push(&self, value: impl IntoLua) -> Result<()> {
        value.push_into_stack(self)
    }

+    /// Pops a value that implements [`FromLua`] from the top of the Lua stack.
+    ///
+    /// Uses up to 1 stack space, does not call `checkstack`.
+    #[allow(clippy::missing_safety_doc)]
+    #[inline(always)]
+    pub unsafe fn pop<R: FromLua>(&self) -> Result<R> {
+        let v = R::from_stack(-1, self)?;
+        ffi::lua_pop(self.state(), 1);
+        Ok(v)
+    }
+
    /// Pushes a `Value` (by reference) onto the Lua stack.
    ///
-    /// Uses 2 stack spaces, does not call `checkstack`.
+    /// Uses up to 2 stack spaces, does not call `checkstack`.
+    #[allow(clippy::missing_safety_doc)]
    pub unsafe fn push_value(&self, value: &Value) -> Result<()> {
        let state = self.state();
        match value {
@@ -773,6 +786,7 @@ impl RawLua {
    /// Pops a value from the Lua stack.
    ///
    /// Uses up to 1 stack spaces, does not call `checkstack`.
+    #[allow(clippy::missing_safety_doc)]
    #[inline]
    pub unsafe fn pop_value(&self) -> Value {
        let value = self.stack_value(-1, None);
@@ -803,15 +817,22 @@ impl RawLua {

            #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit", feature = "luau"))]
            ffi::LUA_TNUMBER => {
-                use crate::types::Number;
-
                let n = ffi::lua_tonumber(state, idx);
                match num_traits::cast(n) {
-                    Some(i) if n.to_bits() == (i as Number).to_bits() => Value::Integer(i),
+                    Some(i) if n.to_bits() == (i as crate::types::Number).to_bits() => Value::Integer(i),
                    _ => Value::Number(n),
                }
            }

+            #[cfg(feature = "luau")]
+            ffi::LUA_TINTEGER => {
+                let i = ffi::lua_tointeger64(state, idx, ptr::null_mut());
+                match num_traits::cast(i) {
+                    Some(i) => Value::Integer(i),
+                    _ => Value::Number(i as crate::types::Number),
+                }
+            }
+
            #[cfg(feature = "luau")]
            ffi::LUA_TVECTOR => {
                let v = ffi::lua_tovector(state, idx);
@@ -824,7 +845,7 @@ impl RawLua {

            ffi::LUA_TSTRING => {
                ffi::lua_xpush(state, self.ref_thread(), idx);
-                Value::String(String(self.pop_ref_thread()))
+                Value::String(LuaString(self.pop_ref_thread()))
            }

            ffi::LUA_TTABLE => {
@@ -949,7 +970,7 @@ impl RawLua {
            // Check if userdata/metatable is already registered
            let type_id = TypeId::of::<T>();
            if let Some(&table_id) = (*self.extra.get()).registered_userdata_t.get(&type_id) {
-                return Ok(table_id as Integer);
+                return Ok(table_id);
            }

            // Create a new metatable from `UserData` definition
@@ -968,7 +989,7 @@ impl RawLua {
            // Check if userdata/metatable is already registered
            let type_id = TypeId::of::<T>();
            if let Some(&table_id) = (*self.extra.get()).registered_userdata_t.get(&type_id) {
-                return Ok(table_id as Integer);
+                return Ok(table_id);
            }

            // Check if metatable creation is pending or create an empty metatable otherwise
@@ -983,7 +1004,7 @@ impl RawLua {
    unsafe fn make_userdata_with_metatable<T>(
        &self,
        data: UserDataStorage<T>,
-        get_metatable_id: impl FnOnce() -> Result<Integer>,
+        get_metatable_id: impl FnOnce() -> Result<c_int>,
    ) -> Result<AnyUserData> {
        let state = self.state();
        let _sg = StackGuard::new(state);
@@ -993,7 +1014,7 @@ impl RawLua {
        let mt_id = get_metatable_id()?;
        let protect = !self.unlikely_memory_error();
        push_userdata(state, data, protect)?;
-        ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, mt_id);
+        ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, mt_id as _);
        ffi::lua_setmetatable(state, -2);

        // Set empty environment for Lua 5.1
@@ -1011,7 +1032,7 @@ impl RawLua {
        Ok(AnyUserData(self.pop_ref()))
    }

-    pub(crate) unsafe fn create_userdata_metatable(&self, registry: RawUserDataRegistry) -> Result<Integer> {
+    pub(crate) unsafe fn create_userdata_metatable(&self, registry: RawUserDataRegistry) -> Result<c_int> {
        let state = self.state();
        let type_id = registry.type_id;

@@ -1027,7 +1048,7 @@ impl RawLua {
        }
        self.register_userdata_metatable(mt_ptr, type_id);

-        Ok(id as Integer)
+        Ok(id)
    }

    pub(crate) unsafe fn push_userdata_metatable(&self, mut registry: RawUserDataRegistry) -> Result<()> {
@@ -1126,7 +1147,7 @@ impl RawLua {
        #[cfg(feature = "luau")]
        if registry.enable_namecall {
            let map: &mut rustc_hash::FxHashMap<_, crate::types::CallbackPtr> =
-                methods_map.get_or_insert_with(Default::default);
+                methods_map.get_or_insert_default();
            for (k, m) in &registry.methods {
                map.insert(k.as_bytes().to_vec(), &**m);
            }
@@ -1219,13 +1240,11 @@ impl RawLua {
            Ok(type_id) => Ok(type_id),
            Err(Error::UserDataTypeMismatch) if ffi::lua_type(state, idx) != ffi::LUA_TUSERDATA => {
                // Report `FromLuaConversionError` instead
-                // 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 type_name = CStr::from_ptr(ffi::lua_typename(state, ffi::lua_type(state, idx)))
+                    .to_str()
+                    .unwrap_or("unknown");
                let message = format!("expected userdata of type '{}'", short_type_name::<T>());
-                Err(Error::from_lua_conversion(idx_type_name, "userdata", message))
+                Err(Error::from_lua_conversion(type_name, "userdata", message))
            }
            Err(err) => Err(err),
        }
@@ -1586,6 +1605,11 @@ unsafe fn load_std_libs(state: *mut ffi::lua_State, libs: StdLib) -> Result<()>
        requiref(state, ffi::LUA_VECLIBNAME, ffi::luaopen_vector, 1)?;
    }

+    #[cfg(feature = "luau")]
+    if libs.contains(StdLib::INTEGER) {
+        requiref(state, ffi::LUA_INTLIBNAME, ffi::luaopen_integer, 1)?;
+    }
+
    if libs.contains(StdLib::MATH) {
        requiref(state, ffi::LUA_MATHLIBNAME, ffi::luaopen_math, 1)?;
    }
@@ -1,11 +1,11 @@
 use std::os::raw::c_int;
-use std::panic::{catch_unwind, AssertUnwindSafe};
+use std::panic::{AssertUnwindSafe, catch_unwind};
 use std::ptr;
 use std::sync::Arc;

 use crate::error::{Error, Result};
 use crate::state::{ExtraData, RawLua};
-use crate::util::{self, get_internal_metatable, WrappedFailure};
+use crate::util::{self, WrappedFailure, get_internal_metatable};

 struct StateGuard<'a>(&'a RawLua, *mut ffi::lua_State);

@@ -73,10 +73,15 @@ impl StdLib {
    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
    pub const VECTOR: StdLib = StdLib(1 << 10);

+    /// [`integer`](https://luau.org/library#integer-library) library
+    #[cfg(any(feature = "luau", doc))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
+    pub const INTEGER: StdLib = StdLib(1 << 11);
+
    /// [`jit`](http://luajit.org/ext_jit.html) library
    #[cfg(any(feature = "luajit", doc))]
    #[cfg_attr(docsrs, doc(cfg(feature = "luajit")))]
-    pub const JIT: StdLib = StdLib(1 << 11);
+    pub const JIT: StdLib = StdLib(1 << 12);

    /// (**unsafe**) [`ffi`](http://luajit.org/ext_ffi.html) library
    #[cfg(any(feature = "luajit", doc))]
@@ -1,9 +1,12 @@
-use std::borrow::{Borrow, Cow};
+//! Lua string handling.
+//!
+//! This module provides types for working with Lua strings from Rust.
+
+use std::borrow::Borrow;
 use std::hash::{Hash, Hasher};
 use std::ops::Deref;
 use std::os::raw::{c_int, c_void};
-use std::string::String as StdString;
-use std::{cmp, fmt, slice, str};
+use std::{cmp, fmt, mem, slice, str};

 use crate::error::{Error, Result};
 use crate::state::Lua;
@@ -21,37 +24,40 @@ use {
 ///
 /// Unlike Rust strings, Lua strings may not be valid UTF-8.
 #[derive(Clone)]
-pub struct String(pub(crate) ValueRef);
+pub struct LuaString(pub(crate) ValueRef);

-impl String {
+impl LuaString {
    /// Get a [`BorrowedStr`] if the Lua string is valid UTF-8.
    ///
+    /// The returned `BorrowedStr` holds a strong reference to the Lua state to guarantee the
+    /// validity of the underlying data.
+    ///
    /// # Examples
    ///
    /// ```
-    /// # use mlua::{Lua, Result, String};
+    /// # use mlua::{Lua, LuaString, Result};
    /// # fn main() -> Result<()> {
    /// # let lua = Lua::new();
    /// let globals = lua.globals();
    ///
-    /// let version: String = globals.get("_VERSION")?;
+    /// let version: LuaString = globals.get("_VERSION")?;
    /// assert!(version.to_str()?.contains("Lua"));
    ///
-    /// let non_utf8: String = lua.load(r#"  "test\255"  "#).eval()?;
+    /// let non_utf8: LuaString = lua.load(r#"  "test\255"  "#).eval()?;
    /// assert!(non_utf8.to_str().is_err());
    /// # Ok(())
    /// # }
    /// ```
    #[inline]
-    pub fn to_str(&self) -> Result<BorrowedStr<'_>> {
+    pub fn to_str(&self) -> Result<BorrowedStr> {
        BorrowedStr::try_from(self)
    }

-    /// Converts this string to a [`StdString`].
+    /// Converts this Lua string to a [`String`].
    ///
    /// Any non-Unicode sequences are replaced with [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD].
    ///
-    /// This method returns [`StdString`] instead of [`Cow<'_, str>`] because lifetime cannot be
+    /// This method returns [`String`] instead of [`Cow<'_, str>`] because lifetime cannot be
    /// bound to a weak Lua object.
    ///
    /// [U+FFFD]: std::char::REPLACEMENT_CHARACTER
@@ -70,11 +76,11 @@ impl String {
    /// # }
    /// ```
    #[inline]
-    pub fn to_string_lossy(&self) -> StdString {
-        StdString::from_utf8_lossy(&self.as_bytes()).into_owned()
+    pub fn to_string_lossy(&self) -> String {
+        String::from_utf8_lossy(&self.as_bytes()).into_owned()
    }

-    /// Returns an object that implements [`Display`] for safely printing a Lua [`String`] that may
+    /// Returns an object that implements [`Display`] for safely printing a [`LuaString`] that may
    /// contain non-Unicode data.
    ///
    /// This may perform lossy conversion.
@@ -86,32 +92,33 @@ impl String {

    /// Get the bytes that make up this string.
    ///
-    /// The returned slice will not contain the terminating null byte, but will contain any null
-    /// bytes embedded into the Lua string.
+    /// The returned `BorrowedStr` holds a strong reference to the Lua state to guarantee the
+    /// validity of the underlying data. The data will not contain the terminating null byte, but
+    /// will contain any null bytes embedded into the Lua string.
    ///
    /// # Examples
    ///
    /// ```
-    /// # use mlua::{Lua, Result, String};
+    /// # use mlua::{Lua, LuaString, Result};
    /// # fn main() -> Result<()> {
    /// # let lua = Lua::new();
-    /// let non_utf8: String = lua.load(r#"  "test\255"  "#).eval()?;
+    /// let non_utf8: LuaString = lua.load(r#"  "test\255"  "#).eval()?;
    /// assert!(non_utf8.to_str().is_err());    // oh no :(
    /// assert_eq!(non_utf8.as_bytes(), &b"test\xff"[..]);
    /// # Ok(())
    /// # }
    /// ```
    #[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 null byte.
-    pub fn as_bytes_with_nul(&self) -> BorrowedBytes<'_> {
-        let BorrowedBytes { buf, borrow, _lua } = BorrowedBytes::from(self);
+    pub fn as_bytes_with_nul(&self) -> BorrowedBytes {
+        let BorrowedBytes { buf, vref, _lua } = BorrowedBytes::from(self);
        // 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 }
+        BorrowedBytes { buf, vref, _lua }
    }

    // Does not return the terminating null byte
@@ -135,7 +142,7 @@ impl String {
        (slice, lua)
    }

-    /// Converts this string to a generic C pointer.
+    /// Converts this Lua string to a generic C pointer.
    ///
    /// There is no way to convert the pointer back to its original value.
    ///
@@ -146,7 +153,7 @@ impl String {
    }
 }

-impl fmt::Debug for String {
+impl fmt::Debug for LuaString {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let bytes = self.as_bytes();
        // Check if the string is valid utf8
@@ -162,12 +169,12 @@ impl fmt::Debug for String {

 // Lua strings are basically `&[u8]` slices, so implement `PartialEq` for anything resembling that.
 //
-// This makes our `String` comparable with `Vec<u8>`, `[u8]`, `&str` and `String`.
+// This makes our `LuaString` comparable with `Vec<u8>`, `[u8]`, `&str` and `String`.
 //
 // The only downside is that this disallows a comparison with `Cow<str>`, as that only implements
 // `AsRef<str>`, which collides with this impl. Requiring `AsRef<str>` would fix that, but limit us
 // in other ways.
-impl<T> PartialEq<T> for String
+impl<T> PartialEq<T> for LuaString
 where
    T: AsRef<[u8]> + ?Sized,
 {
@@ -176,43 +183,43 @@ where
    }
 }

-impl PartialEq for String {
-    fn eq(&self, other: &String) -> bool {
+impl PartialEq for LuaString {
+    fn eq(&self, other: &LuaString) -> bool {
        self.as_bytes() == other.as_bytes()
    }
 }

-impl Eq for String {}
+impl Eq for LuaString {}

-impl<T> PartialOrd<T> for String
+impl<T> PartialOrd<T> for LuaString
 where
    T: AsRef<[u8]> + ?Sized,
 {
    fn partial_cmp(&self, other: &T) -> Option<cmp::Ordering> {
-        self.as_bytes().partial_cmp(&other.as_ref())
+        <[u8]>::partial_cmp(&self.as_bytes(), other.as_ref())
    }
 }

-impl PartialOrd for String {
-    fn partial_cmp(&self, other: &String) -> Option<cmp::Ordering> {
+impl PartialOrd for LuaString {
+    fn partial_cmp(&self, other: &LuaString) -> Option<cmp::Ordering> {
        Some(self.cmp(other))
    }
 }

-impl Ord for String {
-    fn cmp(&self, other: &String) -> cmp::Ordering {
+impl Ord for LuaString {
+    fn cmp(&self, other: &LuaString) -> cmp::Ordering {
        self.as_bytes().cmp(&other.as_bytes())
    }
 }

-impl Hash for String {
+impl Hash for LuaString {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.as_bytes().hash(state);
    }
 }

 #[cfg(feature = "serde")]
-impl Serialize for String {
+impl Serialize for LuaString {
    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
    where
        S: Serializer,
@@ -224,7 +231,7 @@ impl Serialize for String {
    }
 }

-struct Display<'a>(&'a String);
+struct Display<'a>(&'a LuaString);

 impl fmt::Display for Display<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@@ -234,14 +241,14 @@ impl fmt::Display for Display<'_> {
 }

 /// A borrowed string (`&str`) that holds a strong reference to the Lua state.
-pub struct BorrowedStr<'a> {
+pub struct BorrowedStr {
    // `buf` points to a readonly memory managed by Lua
-    pub(crate) buf: &'a str,
-    pub(crate) borrow: Cow<'a, String>,
+    pub(crate) buf: &'static str,
+    pub(crate) vref: ValueRef,
    pub(crate) _lua: Lua,
 }

-impl Deref for BorrowedStr<'_> {
+impl Deref for BorrowedStr {
    type Target = str;

    #[inline(always)]
@@ -250,33 +257,33 @@ impl Deref for BorrowedStr<'_> {
    }
 }

-impl Borrow<str> for BorrowedStr<'_> {
+impl Borrow<str> for BorrowedStr {
    #[inline(always)]
    fn borrow(&self) -> &str {
        self.buf
    }
 }

-impl AsRef<str> for BorrowedStr<'_> {
+impl AsRef<str> for BorrowedStr {
    #[inline(always)]
    fn as_ref(&self) -> &str {
        self.buf
    }
 }

-impl fmt::Display for BorrowedStr<'_> {
+impl fmt::Display for BorrowedStr {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.buf.fmt(f)
    }
 }

-impl fmt::Debug for BorrowedStr<'_> {
+impl fmt::Debug for BorrowedStr {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.buf.fmt(f)
    }
 }

-impl<T> PartialEq<T> for BorrowedStr<'_>
+impl<T> PartialEq<T> for BorrowedStr
 where
    T: AsRef<str>,
 {
@@ -285,9 +292,9 @@ where
    }
 }

-impl Eq for BorrowedStr<'_> {}
+impl Eq for BorrowedStr {}

-impl<T> PartialOrd<T> for BorrowedStr<'_>
+impl<T> PartialOrd<T> for BorrowedStr
 where
    T: AsRef<str>,
 {
@@ -296,36 +303,33 @@ where
    }
 }

-impl Ord for BorrowedStr<'_> {
+impl Ord for BorrowedStr {
    fn cmp(&self, other: &Self) -> cmp::Ordering {
        self.buf.cmp(other.buf)
    }
 }

-impl<'a> TryFrom<&'a String> for BorrowedStr<'a> {
+impl TryFrom<&LuaString> for BorrowedStr {
    type Error = Error;

    #[inline]
-    fn try_from(value: &'a String) -> Result<Self> {
-        let BorrowedBytes { buf, borrow, _lua } = BorrowedBytes::from(value);
-        let buf = str::from_utf8(buf).map_err(|e| Error::FromLuaConversionError {
-            from: "string",
-            to: "&str".to_string(),
-            message: Some(e.to_string()),
-        })?;
-        Ok(Self { buf, borrow, _lua })
+    fn try_from(value: &LuaString) -> Result<Self> {
+        let BorrowedBytes { buf, vref, _lua } = BorrowedBytes::from(value);
+        let buf =
+            str::from_utf8(buf).map_err(|e| Error::from_lua_conversion("string", "&str", e.to_string()))?;
+        Ok(Self { buf, vref, _lua })
    }
 }

 /// A borrowed byte slice (`&[u8]`) that holds a strong reference to the Lua state.
-pub struct BorrowedBytes<'a> {
+pub struct BorrowedBytes {
    // `buf` points to a readonly memory managed by Lua
-    pub(crate) buf: &'a [u8],
-    pub(crate) borrow: Cow<'a, String>,
+    pub(crate) buf: &'static [u8],
+    pub(crate) vref: ValueRef,
    pub(crate) _lua: Lua,
 }

-impl Deref for BorrowedBytes<'_> {
+impl Deref for BorrowedBytes {
    type Target = [u8];

    #[inline(always)]
@@ -334,27 +338,27 @@ impl Deref for BorrowedBytes<'_> {
    }
 }

-impl Borrow<[u8]> for BorrowedBytes<'_> {
+impl Borrow<[u8]> for BorrowedBytes {
    #[inline(always)]
    fn borrow(&self) -> &[u8] {
        self.buf
    }
 }

-impl AsRef<[u8]> for BorrowedBytes<'_> {
+impl AsRef<[u8]> for BorrowedBytes {
    #[inline(always)]
    fn as_ref(&self) -> &[u8] {
        self.buf
    }
 }

-impl fmt::Debug for BorrowedBytes<'_> {
+impl fmt::Debug for BorrowedBytes {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.buf.fmt(f)
    }
 }

-impl<T> PartialEq<T> for BorrowedBytes<'_>
+impl<T> PartialEq<T> for BorrowedBytes
 where
    T: AsRef<[u8]>,
 {
@@ -363,9 +367,9 @@ where
    }
 }

-impl Eq for BorrowedBytes<'_> {}
+impl Eq for BorrowedBytes {}

-impl<T> PartialOrd<T> for BorrowedBytes<'_>
+impl<T> PartialOrd<T> for BorrowedBytes
 where
    T: AsRef<[u8]>,
 {
@@ -374,13 +378,13 @@ where
    }
 }

-impl Ord for BorrowedBytes<'_> {
+impl Ord for BorrowedBytes {
    fn cmp(&self, other: &Self) -> cmp::Ordering {
        self.buf.cmp(other.buf)
    }
 }

-impl<'a> IntoIterator for &'a BorrowedBytes<'_> {
+impl<'a> IntoIterator for &'a BorrowedBytes {
    type Item = &'a u8;
    type IntoIter = slice::Iter<'a, u8>;

@@ -389,18 +393,20 @@ impl<'a> IntoIterator for &'a BorrowedBytes<'_> {
    }
 }

-impl<'a> From<&'a String> for BorrowedBytes<'a> {
+impl From<&LuaString> for BorrowedBytes {
    #[inline]
-    fn from(value: &'a String) -> Self {
+    fn from(value: &LuaString) -> Self {
        let (buf, _lua) = unsafe { value.to_slice() };
-        let borrow = Cow::Borrowed(value);
-        Self { buf, borrow, _lua }
+        let vref = value.0.clone();
+        // SAFETY: The `buf` is valid for the lifetime of the Lua state and occupied slot index
+        let buf = unsafe { mem::transmute::<&[u8], &'static [u8]>(buf) };
+        Self { buf, vref, _lua }
    }
 }

 struct WrappedString<T: AsRef<[u8]>>(T);

-impl String {
+impl LuaString {
    /// Wraps bytes, returning an opaque type that implements [`IntoLua`] trait.
    ///
    /// This function uses [`Lua::create_string`] under the hood.
@@ -415,7 +421,7 @@ impl<T: AsRef<[u8]>> IntoLua for WrappedString<T> {
    }
 }

-impl LuaType for String {
+impl LuaType for LuaString {
    const TYPE_ID: c_int = ffi::LUA_TSTRING;
 }

@@ -424,9 +430,9 @@ mod assertions {
    use super::*;

    #[cfg(not(feature = "send"))]
-    static_assertions::assert_not_impl_any!(String: Send);
+    static_assertions::assert_not_impl_any!(LuaString: Send);
    #[cfg(feature = "send")]
-    static_assertions::assert_impl_all!(String: Send, Sync);
+    static_assertions::assert_impl_all!(LuaString: Send, Sync);
    #[cfg(feature = "send")]
    static_assertions::assert_impl_all!(BorrowedBytes: Send, Sync);
    #[cfg(feature = "send")]
@@ -1,15 +1,167 @@
+//! Lua table handling.
+//!
+//! Tables are Lua's primary data structure, used for arrays, dictionaries, objects, modules,
+//! and more. This module provides types for creating and manipulating Lua tables from Rust.
+//!
+//! # Basic Operations
+//!
+//! Tables support key-value access similar to Rust's `HashMap`:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//! let table = lua.create_table()?;
+//!
+//! // Set and get values
+//! table.set("key", "value")?;
+//! let value: String = table.get("key")?;
+//! assert_eq!(value, "value");
+//!
+//! // Keys and values can be any Lua-compatible type
+//! table.set(1, "first")?;
+//! table.set("nested", lua.create_table()?)?;
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Array Operations
+//!
+//! Tables can be used as arrays with 1-based indexing:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//! let array = lua.create_table()?;
+//!
+//! // Push values to the end (like Vec::push)
+//! array.push("first")?;
+//! array.push("second")?;
+//! array.push("third")?;
+//!
+//! // Pop from the end
+//! let last: String = array.pop()?;
+//! assert_eq!(last, "third");
+//!
+//! // Get length
+//! assert_eq!(array.raw_len(), 2);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Iteration
+//!
+//! Iterate over all key-value pairs with [`Table::pairs`]:
+//!
+//! ```
+//! # use mlua::{Lua, Result, Value};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//! let table = lua.create_table()?;
+//! table.set("a", 1)?;
+//! table.set("b", 2)?;
+//!
+//! for pair in table.pairs::<String, i32>() {
+//!     let (key, value) = pair?;
+//!     println!("{key} = {value}");
+//! }
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! For array portions, use [`Table::sequence_values`]:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//! let array = lua.create_sequence_from(["a", "b", "c"])?;
+//!
+//! for value in array.sequence_values::<String>() {
+//!     println!("{}", value?);
+//! }
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Raw vs Normal Access
+//!
+//! Methods prefixed with `raw_` (like [`Table::raw_get`], [`Table::raw_set`]) bypass
+//! metamethods, directly accessing the table's contents. Normal methods may trigger
+//! `__index`, `__newindex`, and other metamethods:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//!
+//! // raw_set bypasses __newindex metamethod
+//! let t = lua.create_table()?;
+//! t.raw_set("key", "value")?;
+//!
+//! // raw_get bypasses __index metamethod
+//! let v: String = t.raw_get("key")?;
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Metatables
+//!
+//! Tables can have metatables that customize their behavior:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//!
+//! let table = lua.create_table()?;
+//! let metatable = lua.create_table()?;
+//!
+//! // Set a default value via __index
+//! metatable.set("__index", lua.create_function(|_, _: ()| Ok("default"))?)?;
+//! table.set_metatable(Some(metatable))?;
+//!
+//! // Accessing missing keys returns "default"
+//! let value: String = table.get("missing")?;
+//! assert_eq!(value, "default");
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Global Table
+//!
+//! The Lua global environment is itself a table, accessible via [`Lua::globals`]:
+//!
+//! ```
+//! # use mlua::{Lua, Result};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//! let globals = lua.globals();
+//!
+//! // Set a global variable
+//! globals.set("my_var", 42)?;
+//!
+//! // Now accessible from Lua code
+//! let result: i32 = lua.load("my_var + 8").eval()?;
+//! assert_eq!(result, 50);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! [`Lua::globals`]: crate::Lua::globals
+
 use std::collections::HashSet;
 use std::fmt;
 use std::marker::PhantomData;
 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, WeakLua};
 use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti, ObjectLike};
 use crate::types::{Integer, ValueRef};
-use crate::util::{assert_stack, check_stack, get_metatable_ptr, StackGuard};
+use crate::util::{StackGuard, assert_stack, check_stack, get_metatable_ptr};
 use crate::value::{Nil, Value};

 #[cfg(feature = "async")]
@@ -226,15 +378,15 @@ impl Table {
        // Compare using `__eq` metamethod if exists
        // First, check the self for the metamethod.
        // If self does not define it, then check the other table.
-        if let Some(mt) = self.metatable() {
-            if mt.contains_key("__eq")? {
-                return mt.get::<Function>("__eq")?.call((self, other));
-            }
+        if let Some(mt) = self.metatable()
+            && let Some(eq_func) = mt.get::<Option<Function>>("__eq")?
+        {
+            return eq_func.call((self, other));
        }
-        if let Some(mt) = other.metatable() {
-            if mt.contains_key("__eq")? {
-                return mt.get::<Function>("__eq")?.call((self, other));
-            }
+        if let Some(mt) = other.metatable()
+            && let Some(eq_func) = mt.get::<Option<Function>>("__eq")?
+        {
+            return eq_func.call((self, other));
        }

        Ok(false)
@@ -626,10 +778,8 @@ impl Table {
            ffi::lua_pushnil(state);
            while ffi::lua_next(state, -2) != 0 {
                let k = K::from_stack(-2, &lua)?;
-                let v = V::from_stack(-1, &lua)?;
+                let v = lua.pop::<V>()?;
                f(k, v)?;
-                // Keep key for next iteration
-                ffi::lua_pop(state, 1);
            }
        }
        Ok(())
@@ -702,8 +852,7 @@ impl Table {
                if len.is_none() && t == ffi::LUA_TNIL {
                    break;
                }
-                f(V::from_stack(-1, &lua)?)?;
-                ffi::lua_pop(state, 1);
+                f(lua.pop::<V>()?)?;
            }
        }
        Ok(())
@@ -1008,7 +1157,7 @@ impl ObjectLike for Table {
    }

    #[inline]
-    fn to_string(&self) -> Result<StdString> {
+    fn to_string(&self) -> Result<String> {
        Value::Table(Table(self.0.clone())).to_string()
    }

@@ -1070,7 +1219,7 @@ impl Serialize for SerializableTable<'_> {
    where
        S: Serializer,
    {
-        use crate::serde::de::{check_value_for_skip, MapPairs, RecursionGuard};
+        use crate::serde::de::{MapPairs, RecursionGuard, check_value_for_skip};
        use crate::value::SerializableValue;

        let convert_result = |res: Result<()>, serialize_err: Option<S::Error>| match res {
@@ -1098,7 +1247,7 @@ impl Serialize for SerializableTable<'_> {
                seq.serialize_element(&SerializableValue::new(&value, options, Some(visited)))
                    .map_err(|err| {
                        serialize_err = Some(err);
-                        Error::SerializeError(StdString::new())
+                        Error::SerializeError(String::new())
                    })
            });
            convert_result(res, serialize_err)?;
@@ -1123,7 +1272,7 @@ impl Serialize for SerializableTable<'_> {
            )
            .map_err(|err| {
                serialize_err = Some(err);
-                Error::SerializeError(StdString::new())
+                Error::SerializeError(String::new())
            })
        };

@@ -1,3 +1,40 @@
+//! Lua thread (coroutine) handling.
+//!
+//! This module provides types for creating and working with Lua coroutines from Rust.
+//! Coroutines allow cooperative multitasking within a single Lua state by suspending and
+//! resuming execution at well-defined yield points.
+//!
+//! # Basic Usage
+//!
+//! Threads are created via [`Lua::create_thread`] and driven by calling [`Thread::resume`]:
+//!
+//! ```rust
+//! # use mlua::{Lua, Result, Thread};
+//! # fn main() -> Result<()> {
+//! let lua = Lua::new();
+//! let thread: Thread = lua.load(r#"
+//!     coroutine.create(function(a, b)
+//!         coroutine.yield(a + b)
+//!         return a * b
+//!     end)
+//! "#).eval()?;
+//!
+//! assert_eq!(thread.resume::<i32>((3, 4))?, 7);
+//! assert_eq!(thread.resume::<i32>(())?,    12);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Async Support
+//!
+//! When the `async` feature is enabled, a [`Thread`] can be converted into an [`AsyncThread`]
+//! via [`Thread::into_async`], which implements both [`Future`] and [`Stream`].
+//! This integrates Lua coroutines naturally with Rust async runtimes such as Tokio.
+//!
+//! [`Lua::create_thread`]: crate::Lua::create_thread
+//! [`Future`]: std::future::Future
+//! [`Stream`]: futures_util::stream::Stream
+
 use std::fmt;
 use std::os::raw::{c_int, c_void};

@@ -6,7 +43,7 @@ use crate::function::Function;
 use crate::state::RawLua;
 use crate::traits::{FromLuaMulti, IntoLuaMulti};
 use crate::types::{LuaType, ValueRef};
-use crate::util::{check_stack, error_traceback_thread, pop_error, StackGuard};
+use crate::util::{StackGuard, check_stack, error_traceback_thread, pop_error};

 #[cfg(not(feature = "luau"))]
 use crate::{
@@ -69,7 +106,7 @@ impl ThreadStatusInner {
 }

 /// Handle to an internal Lua thread (coroutine).
-#[derive(Clone)]
+#[derive(Clone, PartialEq)]
 pub struct Thread(pub(crate) ValueRef, pub(crate) *mut ffi::lua_State);

 #[cfg(feature = "send")]
@@ -92,7 +129,6 @@ pub struct AsyncThread<R> {

 impl Thread {
    /// Returns reference to the Lua state that this thread is associated with.
-    #[doc(hidden)]
    #[inline(always)]
    pub fn state(&self) -> *mut ffi::lua_State {
        self.1
@@ -259,6 +295,31 @@ impl Thread {
        }
    }

+    /// Returns `true` if this thread is resumable (meaning it can be resumed by calling
+    /// [`Thread::resume`]).
+    #[inline(always)]
+    pub fn is_resumable(&self) -> bool {
+        self.status() == ThreadStatus::Resumable
+    }
+
+    /// Returns `true` if this thread is currently running.
+    #[inline(always)]
+    pub fn is_running(&self) -> bool {
+        self.status() == ThreadStatus::Running
+    }
+
+    /// Returns `true` if this thread has finished executing.
+    #[inline(always)]
+    pub fn is_finished(&self) -> bool {
+        self.status() == ThreadStatus::Finished
+    }
+
+    /// Returns `true` if this thread has raised a Lua error during execution.
+    #[inline(always)]
+    pub fn is_error(&self) -> bool {
+        self.status() == ThreadStatus::Error
+    }
+
    /// Sets a hook function that will periodically be called as Lua code executes.
    ///
    /// This function is similar or [`Lua::set_hook`] except that it sets for the thread.
@@ -295,7 +356,7 @@ impl Thread {
    /// Resets a thread
    ///
    /// In [Lua 5.4]: cleans its call stack and closes all pending to-be-closed variables.
-    /// Returns a error in case of either the original error that stopped the thread or errors
+    /// Returns an error in case of either the original error that stopped the thread or errors
    /// in closing methods.
    ///
    /// In Luau: resets to the initial state of a newly created Lua thread.
@@ -449,6 +510,8 @@ impl Thread {
    /// Please note that Luau links environment table with chunk when loading it into Lua state.
    /// Therefore you need to load chunks into a thread to link with the thread environment.
    ///
+    /// [`Lua::sandbox`]: crate::Lua::sandbox
+    ///
    /// # Examples
    ///
    /// ```
@@ -502,12 +565,6 @@ impl fmt::Debug for Thread {
    }
 }

-impl PartialEq for Thread {
-    fn eq(&self, other: &Self) -> bool {
-        self.0 == other.0
-    }
-}
-
 impl LuaType for Thread {
    const TYPE_ID: c_int = ffi::LUA_TTHREAD;
 }
@@ -523,6 +580,7 @@ impl<R> AsyncThread<R> {
 #[cfg(feature = "async")]
 impl<R> Drop for AsyncThread<R> {
    fn drop(&mut self) {
+        #[allow(clippy::collapsible_if)]
        if self.recycle {
            if let Some(lua) = self.thread.0.lua.try_lock() {
                unsafe {
@@ -1,17 +1,20 @@
+//! Core conversion and extension traits.
+//!
+//! This module provides the fundamental traits for converting values between Rust and Lua,
+//! and for defining native Lua callable functions.
+
 use std::os::raw::c_int;
-use std::string::String as StdString;
 use std::sync::Arc;

 use crate::error::{Error, Result};
 use crate::multi::MultiValue;
 use crate::private::Sealed;
 use crate::state::{Lua, RawLua, WeakLua};
-use crate::types::MaybeSend;
 use crate::util::{check_stack, parse_lookup_path, short_type_name};
 use crate::value::Value;

 #[cfg(feature = "async")]
-use {crate::function::AsyncCallFuture, std::future::Future};
+use crate::function::AsyncCallFuture;

 /// Trait for types convertible to [`Value`].
 pub trait IntoLua: Sized {
@@ -236,7 +239,7 @@ pub trait ObjectLike: Sealed {
    /// Converts the object to a string in a human-readable format.
    ///
    /// This might invoke the `__tostring` metamethod.
-    fn to_string(&self) -> Result<StdString>;
+    fn to_string(&self) -> Result<String>;

    /// Converts the object to a Lua value.
    fn to_value(&self) -> Value;
@@ -246,100 +249,9 @@ pub trait ObjectLike: Sealed {
    fn weak_lua(&self) -> &WeakLua;
 }

-/// A trait for types that can be used as Lua functions.
-pub trait LuaNativeFn<A: FromLuaMulti> {
-    type Output: IntoLuaMulti;
-
-    fn call(&self, args: A) -> Self::Output;
-}
-
-/// A trait for types with mutable state that can be used as Lua functions.
-pub trait LuaNativeFnMut<A: FromLuaMulti> {
-    type Output: IntoLuaMulti;
-
-    fn call(&mut self, args: A) -> Self::Output;
-}
-
-/// A trait for types that returns a future and can be used as Lua functions.
-#[cfg(feature = "async")]
-pub trait LuaNativeAsyncFn<A: FromLuaMulti> {
-    type Output: IntoLuaMulti;
-
-    fn call(&self, args: A) -> impl Future<Output = Self::Output> + MaybeSend + 'static;
-}
-
-macro_rules! impl_lua_native_fn {
-    ($($A:ident),*) => {
-        impl<FN, $($A,)* R> LuaNativeFn<($($A,)*)> for FN
-        where
-            FN: Fn($($A,)*) -> R + MaybeSend + 'static,
-            ($($A,)*): FromLuaMulti,
-            R: IntoLuaMulti,
-        {
-            type Output = R;
-
-            #[allow(non_snake_case)]
-            fn call(&self, args: ($($A,)*)) -> Self::Output {
-                let ($($A,)*) = args;
-                self($($A,)*)
-            }
-        }
-
-        impl<FN, $($A,)* R> LuaNativeFnMut<($($A,)*)> for FN
-        where
-            FN: FnMut($($A,)*) -> R + MaybeSend + 'static,
-            ($($A,)*): FromLuaMulti,
-            R: IntoLuaMulti,
-        {
-            type Output = R;
-
-            #[allow(non_snake_case)]
-            fn call(&mut self, args: ($($A,)*)) -> Self::Output {
-                let ($($A,)*) = args;
-                self($($A,)*)
-            }
-        }
-
-        #[cfg(feature = "async")]
-        impl<FN, $($A,)* Fut, R> LuaNativeAsyncFn<($($A,)*)> for FN
-        where
-            FN: Fn($($A,)*) -> Fut + MaybeSend + 'static,
-            ($($A,)*): FromLuaMulti,
-            Fut: Future<Output = R> + MaybeSend + 'static,
-            R: IntoLuaMulti,
-        {
-            type Output = R;
-
-            #[allow(non_snake_case)]
-            fn call(&self, args: ($($A,)*)) -> impl Future<Output = Self::Output> + MaybeSend + 'static {
-                let ($($A,)*) = args;
-                self($($A,)*)
-            }
-        }
-    };
-}
-
-impl_lua_native_fn!();
-impl_lua_native_fn!(A);
-impl_lua_native_fn!(A, B);
-impl_lua_native_fn!(A, B, C);
-impl_lua_native_fn!(A, B, C, D);
-impl_lua_native_fn!(A, B, C, D, E);
-impl_lua_native_fn!(A, B, C, D, E, F);
-impl_lua_native_fn!(A, B, C, D, E, F, G);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M, N);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O);
-impl_lua_native_fn!(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P);
-
 pub(crate) trait ShortTypeName {
    #[inline(always)]
-    fn type_name() -> StdString {
+    fn type_name() -> String {
        short_type_name::<Self>()
    }
 }
@@ -128,6 +128,18 @@ pub trait MaybeSend {}
 #[cfg(not(feature = "send"))]
 impl<T> MaybeSend for T {}

+/// A trait that adds `Sync` requirement if `send` feature is enabled.
+#[cfg(feature = "send")]
+pub trait MaybeSync: Sync {}
+#[cfg(feature = "send")]
+impl<T: Sync> MaybeSync for T {}
+
+/// A trait that adds `Sync` requirement if `send` feature is enabled.
+#[cfg(not(feature = "send"))]
+pub trait MaybeSync {}
+#[cfg(not(feature = "send"))]
+impl<T> MaybeSync for T {}
+
 pub(crate) struct DestructedUserdata;

 pub(crate) trait LuaType {
@@ -69,7 +69,7 @@ mod inner {

        #[inline(always)]
        fn deref(&self) -> &Self::Target {
-            &self.0 .0
+            &self.0.0
        }
    }
 }
@@ -55,10 +55,10 @@ impl Drop for ValueRef {
        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) };
-                }
+            if XRc::into_inner(index).is_some()
+                && let Some(lua) = self.lua.try_lock()
+            {
+                unsafe { lua.drop_ref(self) }
            }
        }
    }
@@ -1,18 +1,22 @@
+//! Lua userdata handling.
+//!
+//! This module provides types for creating and working with Lua userdata from Rust.
+
 use std::any::TypeId;
 use std::ffi::CStr;
 use std::fmt;
 use std::hash::Hash;
 use std::os::raw::{c_char, c_void};
-use std::string::String as StdString;

+use crate::Either;
 use crate::error::{Error, Result};
 use crate::function::Function;
 use crate::state::Lua;
-use crate::string::String;
+use crate::string::LuaString;
 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, short_type_name, take_userdata, StackGuard};
+use crate::types::{MaybeSend, MaybeSync, ValueRef};
+use crate::util::{StackGuard, check_stack, get_userdata, push_string, short_type_name, take_userdata};
 use crate::value::Value;

 #[cfg(feature = "async")]
@@ -26,12 +30,12 @@ use {

 // Re-export for convenience
 pub(crate) use cell::UserDataStorage;
-pub use r#ref::{UserDataRef, UserDataRefMut};
+pub use r#ref::{UserDataOwned, UserDataRef, UserDataRefMut};
 pub use registry::UserDataRegistry;
 pub(crate) use registry::{RawUserDataRegistry, UserDataProxy};
 pub(crate) use util::{
-    borrow_userdata_scoped, borrow_userdata_scoped_mut, collect_userdata, init_userdata_metatable,
-    TypeIdHints,
+    TypeIdHints, borrow_userdata_scoped, borrow_userdata_scoped_mut, collect_userdata,
+    init_userdata_metatable,
 };

 /// Kinds of metamethods that can be overridden.
@@ -124,6 +128,11 @@ pub enum MetaMethod {
    ///
    /// This is not an operator, but will be called by methods such as `tostring` and `print`.
    ToString,
+    /// The `__todebugstring` metamethod for debug purposes.
+    ///
+    /// This is an mlua-specific metamethod that can be used to provide debug representation for
+    /// userdata.
+    ToDebugString,
    /// The `__pairs` metamethod.
    ///
    /// This is not an operator, but it will be called by the built-in `pairs` function.
@@ -185,7 +194,7 @@ impl PartialEq<MetaMethod> for &str {
    }
 }

-impl PartialEq<MetaMethod> for StdString {
+impl PartialEq<MetaMethod> for String {
    fn eq(&self, other: &MetaMethod) -> bool {
        self == other.name()
    }
@@ -233,6 +242,7 @@ impl MetaMethod {
            MetaMethod::NewIndex => "__newindex",
            MetaMethod::Call => "__call",
            MetaMethod::ToString => "__tostring",
+            MetaMethod::ToDebugString => "__todebugstring",

            #[cfg(any(
                feature = "lua55",
@@ -279,7 +289,7 @@ impl AsRef<str> for MetaMethod {
    }
 }

-impl From<MetaMethod> for StdString {
+impl From<MetaMethod> for String {
    #[inline]
    fn from(method: MetaMethod) -> Self {
        method.name().to_owned()
@@ -295,7 +305,7 @@ 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 Into<StdString>, method: M)
+    fn add_method<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -306,7 +316,7 @@ 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 Into<StdString>, method: M)
+    fn add_method_mut<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -319,8 +329,7 @@ pub trait UserDataMethods<T> {
    ///
    /// 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)
+    fn add_method_once<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(&Lua, T, A) -> Result<R> + MaybeSend + 'static,
@@ -342,7 +351,7 @@ 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 Into<StdString>, method: M)
+    fn add_async_method<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -357,7 +366,7 @@ 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 Into<StdString>, method: M)
+    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -374,8 +383,7 @@ pub trait UserDataMethods<T> {
    /// [`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)
+    fn add_async_method_once<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, T, A) -> MR + MaybeSend + 'static,
@@ -398,7 +406,7 @@ pub trait UserDataMethods<T> {
    /// 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 Into<StdString>, function: F)
+    fn add_function<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -409,7 +417,7 @@ 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 Into<StdString>, function: F)
+    fn add_function_mut<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -423,7 +431,7 @@ 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 Into<StdString>, function: F)
+    fn add_async_function<F, A, FR, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -438,7 +446,7 @@ 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 Into<StdString>, method: M)
+    fn add_meta_method<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -452,7 +460,7 @@ 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 Into<StdString>, method: M)
+    fn add_meta_method_mut<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -468,7 +476,7 @@ 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 Into<StdString>, method: M)
+    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -484,7 +492,7 @@ 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 Into<StdString>, method: M)
+    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -497,7 +505,7 @@ 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 Into<StdString>, function: F)
+    fn add_meta_function<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -508,7 +516,7 @@ 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 Into<StdString>, function: F)
+    fn add_meta_function_mut<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -524,7 +532,7 @@ 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 Into<StdString>, function: F)
+    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -543,7 +551,7 @@ 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 Into<StdString>, value: V)
+    fn add_field<V>(&mut self, name: impl Into<String>, value: V)
    where
        V: IntoLua + 'static;

@@ -554,7 +562,7 @@ 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 Into<StdString>, method: M)
+    fn add_field_method_get<M, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: Fn(&Lua, &T) -> Result<R> + MaybeSend + 'static,
        R: IntoLua;
@@ -567,21 +575,21 @@ 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 Into<StdString>, method: M)
+    fn add_field_method_set<M, A>(&mut self, name: impl Into<String>, 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 Into<StdString>, function: F)
+    fn add_field_function_get<F, R>(&mut self, name: impl Into<String>, 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 Into<StdString>, function: F)
+    fn add_field_function_set<F, A>(&mut self, name: impl Into<String>, function: F)
    where
        F: FnMut(&Lua, AnyUserData, A) -> Result<()> + MaybeSend + 'static,
        A: FromLua;
@@ -594,7 +602,7 @@ 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 Into<StdString>, value: V)
+    fn add_meta_field<V>(&mut self, name: impl Into<String>, value: V)
    where
        V: IntoLua + 'static;

@@ -606,7 +614,7 @@ 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 Into<StdString>, f: F)
+    fn add_meta_field_with<F, R>(&mut self, name: impl Into<String>, f: F)
    where
        F: FnOnce(&Lua) -> Result<R> + 'static,
        R: IntoLua;
@@ -706,7 +714,7 @@ pub trait UserData: Sized {
 ///
 /// [`is`]: crate::AnyUserData::is
 /// [`borrow`]: crate::AnyUserData::borrow
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, PartialEq)]
 pub struct AnyUserData(pub(crate) ValueRef);

 impl AnyUserData {
@@ -1021,8 +1029,8 @@ impl AnyUserData {

    /// 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>> {
+    /// If no type name is set, returns `userdata`.
+    pub fn type_name(&self) -> Result<LuaString> {
        let lua = self.0.lua.lock();
        let state = lua.state();
        unsafe {
@@ -1039,8 +1047,8 @@ impl AnyUserData {
                ffi::luaL_getmetafield(state, -1, MetaMethod::Type.as_cstr().as_ptr())
            };
            match name_type {
-                ffi::LUA_TSTRING => Ok(Some(String(lua.pop_ref()).to_str()?.to_owned())),
-                _ => Ok(None),
+                ffi::LUA_TSTRING => Ok(LuaString(lua.pop_ref())),
+                _ => lua.create_string(b"userdata"),
            }
        }
    }
@@ -1076,6 +1084,48 @@ impl AnyUserData {
        };
        is_serializable().unwrap_or(false)
    }
+
+    unsafe fn invoke_tostring_dbg(&self) -> Result<Option<String>> {
+        let lua = self.0.lua.lock();
+        let state = lua.state();
+        let _guard = StackGuard::new(state);
+        check_stack(state, 3)?;
+
+        lua.push_ref(&self.0);
+        protect_lua!(state, 1, 1, fn(state) {
+            // Try `__todebugstring` metamethod first, then `__tostring`
+            #[allow(clippy::collapsible_if)]
+            if ffi::luaL_callmeta(state, -1, cstr!("__todebugstring")) == 0 {
+                if ffi::luaL_callmeta(state, -1, cstr!("__tostring")) == 0 {
+                    ffi::lua_pushnil(state);
+                }
+            }
+        })?;
+        Ok(lua.pop_value().as_string().map(|s| s.to_string_lossy()))
+    }
+
+    pub(crate) fn fmt_pretty(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        // Try converting to a (debug) string first, with fallback to `__name/__type`
+        match unsafe { self.invoke_tostring_dbg() } {
+            Ok(Some(s)) => write!(fmt, "{s}"),
+            _ => {
+                let name = self.type_name().ok();
+                let name = (name.as_ref())
+                    .map(|s| Either::Left(s.display()))
+                    .unwrap_or(Either::Right("userdata"));
+                write!(fmt, "{name}: {:?}", self.to_pointer())
+            }
+        }
+    }
+}
+
+impl fmt::Debug for AnyUserData {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        if fmt.alternate() {
+            return self.fmt_pretty(fmt);
+        }
+        fmt.debug_tuple("AnyUserData").field(&self.0).finish()
+    }
 }

 /// Handle to a [`AnyUserData`] metatable.
@@ -1126,13 +1176,13 @@ impl UserDataMetatable {
 /// It skips restricted metamethods, such as `__gc` or `__metatable`.
 ///
 /// This struct is created by the [`UserDataMetatable::pairs`] method.
-pub struct UserDataMetatablePairs<'a, V>(TablePairs<'a, StdString, V>);
+pub struct UserDataMetatablePairs<'a, V>(TablePairs<'a, String, V>);

 impl<V> Iterator for UserDataMetatablePairs<'_, V>
 where
    V: FromLua,
 {
-    type Item = Result<(StdString, V)>;
+    type Item = Result<(String, V)>;

    fn next(&mut self) -> Option<Self::Item> {
        loop {
@@ -1172,7 +1222,7 @@ impl AnyUserData {
    /// Wraps any Rust type, returning an opaque type that implements [`IntoLua`] trait.
    ///
    /// This function uses [`Lua::create_any_userdata`] under the hood.
-    pub fn wrap<T: MaybeSend + 'static>(data: T) -> impl IntoLua {
+    pub fn wrap<T: MaybeSend + MaybeSync + 'static>(data: T) -> impl IntoLua {
        WrappedUserdata(move |lua| lua.create_any_userdata(data))
    }

@@ -1182,7 +1232,7 @@ impl AnyUserData {
    /// This function uses [`Lua::create_ser_any_userdata`] under the hood.
    #[cfg(feature = "serde")]
    #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
-    pub fn wrap_ser<T: Serialize + MaybeSend + 'static>(data: T) -> impl IntoLua {
+    pub fn wrap_ser<T: Serialize + MaybeSend + MaybeSync + 'static>(data: T) -> impl IntoLua {
        WrappedUserdata(move |lua| lua.create_ser_any_userdata(data))
    }
 }
@@ -1,4 +1,4 @@
-use std::cell::{RefCell, UnsafeCell};
+use std::cell::RefCell;

 #[cfg(feature = "serde")]
 use serde::ser::{Serialize, Serializer};
@@ -6,14 +6,14 @@ use serde::ser::{Serialize, Serializer};
 use crate::error::{Error, Result};
 use crate::types::XRc;

-use super::lock::{RawLock, UserDataLock};
+use super::lock::{RawLock, RwLock, UserDataLock};
 use super::r#ref::{UserDataRef, UserDataRefMut};

 #[cfg(all(feature = "serde", not(feature = "send")))]
 type DynSerialize = dyn erased_serde::Serialize;

 #[cfg(all(feature = "serde", feature = "send"))]
-type DynSerialize = dyn erased_serde::Serialize + Send;
+type DynSerialize = dyn erased_serde::Serialize + Send + Sync;

 pub(crate) enum UserDataStorage<T> {
    Owned(UserDataVariant<T>),
@@ -23,9 +23,9 @@ pub(crate) enum UserDataStorage<T> {
 // A enum for storing userdata values.
 // It's stored inside a Lua VM and protected by the outer `ReentrantMutex`.
 pub(crate) enum UserDataVariant<T> {
-    Default(XRc<UserDataCell<T>>),
+    Default(XRc<RwLock<T>>),
    #[cfg(feature = "serde")]
-    Serializable(XRc<UserDataCell<Box<DynSerialize>>>, bool), // bool is `is_sync`
+    Serializable(XRc<RwLock<Box<DynSerialize>>>),
 }

 impl<T> Clone for UserDataVariant<T> {
@@ -34,7 +34,7 @@ impl<T> Clone for UserDataVariant<T> {
        match self {
            Self::Default(inner) => Self::Default(XRc::clone(inner)),
            #[cfg(feature = "serde")]
-            Self::Serializable(inner, is_sync) => Self::Serializable(XRc::clone(inner), *is_sync),
+            Self::Serializable(inner) => Self::Serializable(XRc::clone(inner)),
        }
    }
 }
@@ -42,10 +42,12 @@ impl<T> Clone for UserDataVariant<T> {
 impl<T> UserDataVariant<T> {
    #[inline(always)]
    pub(super) fn try_borrow_scoped<R>(&self, f: impl FnOnce(&T) -> R) -> Result<R> {
-        // We don't need to check for `T: Sync` because when this method is used (internally),
-        // Lua mutex is already locked.
-        // If non-`Sync` userdata is already borrowed by another thread (via `UserDataRef`), it will be
-        // exclusively locked.
+        // Shared (read) lock is always correct for in-place borrows:
+        // - this method is called internally while the Lua mutex is held, ensuring exclusive Lua-level
+        //   access per call frame
+        // - with `send` feature, all owned userdata satisfies `T: Sync`, so simultaneous shared references
+        //   from multiple threads are sound
+        // - without `send` feature, single-threaded execution makes shared lock safe for any `T`
        let _guard = (self.raw_lock().try_lock_shared_guarded()).map_err(|_| Error::UserDataBorrowError)?;
        Ok(f(unsafe { &*self.as_ptr() }))
    }
@@ -78,10 +80,12 @@ impl<T> UserDataVariant<T> {
            return Err(Error::UserDataBorrowMutError);
        }
        Ok(match self {
-            Self::Default(inner) => XRc::into_inner(inner).unwrap().value.into_inner(),
+            Self::Default(inner) => XRc::into_inner(inner).unwrap().into_inner(),
            #[cfg(feature = "serde")]
-            Self::Serializable(inner, _) => unsafe {
-                let raw = Box::into_raw(XRc::into_inner(inner).unwrap().value.into_inner());
+            Self::Serializable(inner) => unsafe {
+                // The serde variant erases `T` to `Box<DynSerialize>`, so we
+                // must cast the raw pointer back to recover the concrete type.
+                let raw = Box::into_raw(XRc::into_inner(inner).unwrap().into_inner());
                *Box::from_raw(raw as *mut T)
            },
        })
@@ -92,25 +96,25 @@ impl<T> UserDataVariant<T> {
        match self {
            Self::Default(inner) => XRc::strong_count(inner),
            #[cfg(feature = "serde")]
-            Self::Serializable(inner, _) => XRc::strong_count(inner),
+            Self::Serializable(inner) => XRc::strong_count(inner),
        }
    }

    #[inline(always)]
    pub(super) fn raw_lock(&self) -> &RawLock {
        match self {
-            Self::Default(inner) => &inner.raw_lock,
+            Self::Default(inner) => unsafe { inner.raw() },
            #[cfg(feature = "serde")]
-            Self::Serializable(inner, _) => &inner.raw_lock,
+            Self::Serializable(inner) => unsafe { inner.raw() },
        }
    }

    #[inline(always)]
    pub(super) fn as_ptr(&self) -> *mut T {
        match self {
-            Self::Default(inner) => inner.value.get(),
+            Self::Default(inner) => inner.data_ptr(),
            #[cfg(feature = "serde")]
-            Self::Serializable(inner, _) => unsafe { &mut **(inner.value.get() as *mut Box<T>) },
+            Self::Serializable(inner) => unsafe { (&mut **inner.data_ptr()) as *mut DynSerialize as *mut T },
        }
    }
 }
@@ -119,51 +123,16 @@ impl<T> UserDataVariant<T> {
 impl Serialize for UserDataStorage<()> {
    fn serialize<S: Serializer>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error> {
        match self {
-            Self::Owned(variant @ UserDataVariant::Serializable(inner, is_sync)) => unsafe {
-                #[cfg(feature = "send")]
-                if *is_sync {
-                    let _guard = (variant.raw_lock().try_lock_shared_guarded())
-                        .map_err(|_| serde::ser::Error::custom(Error::UserDataBorrowError))?;
-                    (*inner.value.get()).serialize(serializer)
-                } else {
-                    let _guard = (variant.raw_lock().try_lock_exclusive_guarded())
-                        .map_err(|_| serde::ser::Error::custom(Error::UserDataBorrowError))?;
-                    (*inner.value.get()).serialize(serializer)
-                }
-                #[cfg(not(feature = "send"))]
-                {
-                    let _ = is_sync;
-                    let _guard = (variant.raw_lock().try_lock_shared_guarded())
-                        .map_err(|_| serde::ser::Error::custom(Error::UserDataBorrowError))?;
-                    (*inner.value.get()).serialize(serializer)
-                }
+            Self::Owned(variant @ UserDataVariant::Serializable(inner)) => unsafe {
+                let _guard = (variant.raw_lock().try_lock_shared_guarded())
+                    .map_err(|_| serde::ser::Error::custom(Error::UserDataBorrowError))?;
+                (*inner.data_ptr()).serialize(serializer)
            },
            _ => Err(serde::ser::Error::custom("cannot serialize <userdata>")),
        }
    }
 }

-/// A type that provides interior mutability for a userdata value (thread-safe).
-pub(crate) struct UserDataCell<T> {
-    raw_lock: RawLock,
-    value: UnsafeCell<T>,
-}
-
-#[cfg(feature = "send")]
-unsafe impl<T: Send> Send for UserDataCell<T> {}
-#[cfg(feature = "send")]
-unsafe impl<T: Send> Sync for UserDataCell<T> {}
-
-impl<T> UserDataCell<T> {
-    #[inline(always)]
-    fn new(value: T) -> Self {
-        UserDataCell {
-            raw_lock: RawLock::INIT,
-            value: UnsafeCell::new(value),
-        }
-    }
-}
-
 pub(crate) enum ScopedUserDataVariant<T> {
    Ref(*const T),
    RefMut(RefCell<*mut T>),
@@ -173,10 +142,10 @@ pub(crate) enum ScopedUserDataVariant<T> {
 impl<T> Drop for ScopedUserDataVariant<T> {
    #[inline]
    fn drop(&mut self) {
-        if let Self::Boxed(value) = self {
-            if let Ok(value) = value.try_borrow_mut() {
-                unsafe { drop(Box::from_raw(*value)) };
-            }
+        if let Self::Boxed(value) = self
+            && let Ok(value) = value.try_borrow_mut()
+        {
+            unsafe { drop(Box::from_raw(*value)) }
        }
    }
 }
@@ -184,7 +153,7 @@ impl<T> Drop for ScopedUserDataVariant<T> {
 impl<T: 'static> UserDataStorage<T> {
    #[inline(always)]
    pub(crate) fn new(data: T) -> Self {
-        Self::Owned(UserDataVariant::Default(XRc::new(UserDataCell::new(data))))
+        Self::Owned(UserDataVariant::Default(XRc::new(RwLock::new(data))))
    }

    #[inline(always)]
@@ -201,11 +170,10 @@ impl<T: 'static> UserDataStorage<T> {
    #[inline(always)]
    pub(crate) fn new_ser(data: T) -> Self
    where
-        T: Serialize + crate::types::MaybeSend,
+        T: Serialize + crate::types::MaybeSend + crate::types::MaybeSync,
    {
        let data = Box::new(data) as Box<DynSerialize>;
-        let is_sync = super::util::is_sync::<T>();
-        let variant = UserDataVariant::Serializable(XRc::new(UserDataCell::new(data)), is_sync);
+        let variant = UserDataVariant::Serializable(XRc::new(RwLock::new(data)));
        Self::Owned(variant)
    }

@@ -1,6 +1,4 @@
 pub(crate) trait UserDataLock {
-    const INIT: Self;
-
    fn is_locked(&self) -> bool;
    fn try_lock_shared(&self) -> bool;
    fn try_lock_exclusive(&self) -> bool;
@@ -48,12 +46,12 @@ impl<L: UserDataLock + ?Sized> Drop for LockGuard<'_, L> {
    }
 }

-pub(crate) use lock_impl::RawLock;
+pub(crate) use lock_impl::{RawLock, RwLock};

 #[cfg(not(feature = "send"))]
 #[cfg(not(tarpaulin_include))]
 mod lock_impl {
-    use std::cell::Cell;
+    use std::cell::{Cell, UnsafeCell};

    // Positive values represent the number of read references.
    // Negative values represent the number of write references (only one allowed).
@@ -62,9 +60,6 @@ mod lock_impl {
    const UNUSED: isize = 0;

    impl super::UserDataLock for RawLock {
-        #[allow(clippy::declare_interior_mutable_const)]
-        const INIT: Self = Cell::new(UNUSED);
-
        #[inline(always)]
        fn is_locked(&self) -> bool {
            self.get() != UNUSED
@@ -72,7 +67,7 @@ mod lock_impl {

        #[inline(always)]
        fn try_lock_shared(&self) -> bool {
-            let flag = self.get().wrapping_add(1);
+            let flag = self.get().checked_add(1).expect("userdata lock count overflow");
            if flag <= UNUSED {
                return false;
            }
@@ -104,41 +99,71 @@ mod lock_impl {
            self.set(flag + 1);
        }
    }
+
+    /// A cheap single-threaded read-write lock pairing a `parking_lot::RwLock` type.
+    pub(crate) struct RwLock<T> {
+        lock: RawLock,
+        data: UnsafeCell<T>,
+    }
+
+    impl<T> RwLock<T> {
+        /// Creates a new `RwLock` containing the given value.
+        #[inline(always)]
+        pub(crate) fn new(value: T) -> Self {
+            RwLock {
+                lock: RawLock::new(UNUSED),
+                data: UnsafeCell::new(value),
+            }
+        }
+
+        /// Returns a reference to the underlying raw lock.
+        #[inline(always)]
+        pub(crate) unsafe fn raw(&self) -> &RawLock {
+            &self.lock
+        }
+
+        /// Returns a raw pointer to the underlying data.
+        #[inline(always)]
+        pub(crate) fn data_ptr(&self) -> *mut T {
+            self.data.get()
+        }
+
+        /// Consumes this `RwLock`, returning the underlying data.
+        #[inline(always)]
+        pub(crate) fn into_inner(self) -> T {
+            self.data.into_inner()
+        }
+    }
 }

 #[cfg(feature = "send")]
 mod lock_impl {
-    use parking_lot::lock_api::RawRwLock;
-
-    pub(crate) type RawLock = parking_lot::RawRwLock;
+    pub(crate) use parking_lot::{RawRwLock as RawLock, RwLock};

    impl super::UserDataLock for RawLock {
-        #[allow(clippy::declare_interior_mutable_const)]
-        const INIT: Self = <Self as parking_lot::lock_api::RawRwLock>::INIT;
-
        #[inline(always)]
        fn is_locked(&self) -> bool {
-            RawRwLock::is_locked(self)
+            parking_lot::lock_api::RawRwLock::is_locked(self)
        }

        #[inline(always)]
        fn try_lock_shared(&self) -> bool {
-            RawRwLock::try_lock_shared(self)
+            parking_lot::lock_api::RawRwLock::try_lock_shared(self)
        }

        #[inline(always)]
        fn try_lock_exclusive(&self) -> bool {
-            RawRwLock::try_lock_exclusive(self)
+            parking_lot::lock_api::RawRwLock::try_lock_exclusive(self)
        }

        #[inline(always)]
        unsafe fn unlock_shared(&self) {
-            RawRwLock::unlock_shared(self)
+            parking_lot::lock_api::RawRwLock::unlock_shared(self)
        }

        #[inline(always)]
        unsafe fn unlock_exclusive(&self) {
-            RawRwLock::unlock_exclusive(self)
+            parking_lot::lock_api::RawRwLock::unlock_exclusive(self)
        }
    }
 }
@@ -1,12 +1,10 @@
-use std::string::String as StdString;
-
+use crate::Function;
 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;
 use crate::value::Value;
-use crate::Function;

 #[cfg(feature = "async")]
 use crate::function::AsyncCallFuture;
@@ -88,7 +86,7 @@ impl ObjectLike for AnyUserData {
    }

    #[inline]
-    fn to_string(&self) -> Result<StdString> {
+    fn to_string(&self) -> Result<String> {
        Value::UserData(self.clone()).to_string()
    }

@@ -1,4 +1,4 @@
-use std::any::{type_name, TypeId};
+use std::any::{TypeId, type_name};
 use std::ops::{Deref, DerefMut};
 use std::os::raw::c_int;
 use std::{fmt, mem};
@@ -7,12 +7,11 @@ use crate::error::{Error, Result};
 use crate::state::{Lua, RawLua};
 use crate::traits::FromLua;
 use crate::userdata::AnyUserData;
-use crate::util::get_userdata;
+use crate::util::{check_stack, get_userdata, take_userdata};
 use crate::value::Value;

 use super::cell::{UserDataStorage, UserDataVariant};
 use super::lock::{LockGuard, RawLock, UserDataLock};
-use super::util::is_sync;

 #[cfg(feature = "userdata-wrappers")]
 use {
@@ -63,11 +62,10 @@ impl<T> TryFrom<UserDataVariant<T>> for UserDataRef<T> {

    #[inline]
    fn try_from(variant: UserDataVariant<T>) -> Result<Self> {
-        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()
-        };
+        // Shared (read) lock is always correct:
+        // - with `send` feature, `T: Sync` is guaranteed by the `MaybeSync` bound on userdata creation
+        // - without `send` feature, single-threaded access makes shared lock safe for any `T`
+        let guard = variant.raw_lock().try_lock_shared_guarded();
        let guard = guard.map_err(|_| Error::UserDataBorrowError)?;
        let guard = unsafe { mem::transmute::<LockGuard<_>, LockGuard<'static, _>>(guard) };
        Ok(UserDataRef::from_parts(UserDataRefInner::Default(variant), guard))
@@ -442,15 +440,75 @@ impl<T> DerefMut for UserDataRefMutInner<T> {
    }
 }

+/// A wrapper type that takes ownership of a userdata value.
+///
+/// It implements [`FromLua`] and can be used to receive a typed userdata from Lua by taking
+/// ownership of it.
+/// The original Lua userdata is marked as destructed and cannot be used further.
+pub struct UserDataOwned<T>(pub T);
+
+impl<T> Deref for UserDataOwned<T> {
+    type Target = T;
+
+    #[inline]
+    fn deref(&self) -> &T {
+        &self.0
+    }
+}
+
+impl<T> DerefMut for UserDataOwned<T> {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut T {
+        &mut self.0
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for UserDataOwned<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        (**self).fmt(f)
+    }
+}
+
+impl<T: fmt::Display> fmt::Display for UserDataOwned<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        (**self).fmt(f)
+    }
+}
+
+impl<T: 'static> FromLua for UserDataOwned<T> {
+    fn from_lua(value: Value, _: &Lua) -> Result<Self> {
+        try_value_to_userdata::<T>(value)?.take().map(UserDataOwned)
+    }
+
+    unsafe fn from_stack(idx: c_int, lua: &RawLua) -> Result<Self> {
+        let state = lua.state();
+        let type_id = lua.get_userdata_type_id::<T>(state, idx)?;
+        match type_id {
+            Some(type_id) if type_id == TypeId::of::<T>() => {
+                let ud = get_userdata::<UserDataStorage<T>>(state, idx);
+                if (*ud).has_exclusive_access() {
+                    check_stack(state, 1)?;
+                    take_userdata::<UserDataStorage<T>>(state, idx)
+                        .into_inner()
+                        .map(UserDataOwned)
+                } else {
+                    Err(Error::UserDataBorrowMutError)
+                }
+            }
+            _ => Err(Error::UserDataTypeMismatch),
+        }
+    }
+}
+
 #[inline]
 fn try_value_to_userdata<T>(value: Value) -> Result<AnyUserData> {
    match value {
        Value::UserData(ud) => Ok(ud),
-        _ => Err(Error::FromLuaConversionError {
-            from: value.type_name(),
-            to: "userdata".to_string(),
-            message: Some(format!("expected userdata of type {}", type_name::<T>())),
-        }),
+        _ => Err(Error::from_lua_conversion(
+            value.type_name(),
+            "userdata",
+            format!("expected userdata of type {}", type_name::<T>()),
+        )),
    }
 }

@@ -466,6 +524,10 @@ mod assertions {
    static_assertions::assert_impl_all!(UserDataRefMut<()>: Sync, Send);
    #[cfg(feature = "send")]
    static_assertions::assert_not_impl_all!(UserDataRefMut<std::rc::Rc<()>>: Send, Sync);
+    #[cfg(feature = "send")]
+    static_assertions::assert_impl_all!(UserDataOwned<()>: Send, Sync);
+    #[cfg(feature = "send")]
+    static_assertions::assert_not_impl_all!(UserDataOwned<std::rc::Rc<()>>: Send, Sync);

    #[cfg(not(feature = "send"))]
    static_assertions::assert_not_impl_all!(UserDataRef<()>: Send, Sync);
@@ -4,15 +4,14 @@ use std::any::TypeId;
 use std::cell::RefCell;
 use std::marker::PhantomData;
 use std::os::raw::c_void;
-use std::string::String as StdString;

 use crate::error::{Error, Result};
 use crate::state::{Lua, LuaGuard};
 use crate::traits::{FromLua, FromLuaMulti, IntoLua, IntoLuaMulti};
 use crate::types::{Callback, MaybeSend};
 use crate::userdata::{
-    borrow_userdata_scoped, borrow_userdata_scoped_mut, AnyUserData, MetaMethod, TypeIdHints, UserData,
-    UserDataFields, UserDataMethods, UserDataStorage,
+    AnyUserData, MetaMethod, TypeIdHints, UserData, UserDataFields, UserDataMethods, UserDataStorage,
+    borrow_userdata_scoped, borrow_userdata_scoped_mut,
 };
 use crate::util::short_type_name;
 use crate::value::Value;
@@ -55,7 +54,7 @@ pub(crate) struct RawUserDataRegistry {

    pub(crate) destructor: ffi::lua_CFunction,
    pub(crate) type_id: Option<TypeId>,
-    pub(crate) type_name: StdString,
+    pub(crate) type_name: String,

    #[cfg(feature = "luau")]
    pub(crate) enable_namecall: bool,
@@ -368,7 +367,7 @@ impl<T> UserDataRegistry<T> {
                        method: name.to_string(),
                        type_name: value.type_name(),
                        message: Some("expected nil, table or function".to_string()),
-                    })
+                    });
                }
            }
        }
@@ -382,12 +381,12 @@ impl<T> UserDataRegistry<T> {
 }

 // Returns function name for the type `T`, without the module path
-fn get_function_name<T>(name: &str) -> StdString {
+fn get_function_name<T>(name: &str) -> String {
    format!("{}.{name}", short_type_name::<T>())
 }

 impl<T> UserDataFields<T> for UserDataRegistry<T> {
-    fn add_field<V>(&mut self, name: impl Into<StdString>, value: V)
+    fn add_field<V>(&mut self, name: impl Into<String>, value: V)
    where
        V: IntoLua + 'static,
    {
@@ -395,7 +394,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
        self.raw.fields.push((name, value.into_lua(self.lua.lua())));
    }

-    fn add_field_method_get<M, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_field_method_get<M, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: Fn(&Lua, &T) -> Result<R> + MaybeSend + 'static,
        R: IntoLua,
@@ -405,7 +404,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
        self.raw.field_getters.push((name, callback));
    }

-    fn add_field_method_set<M, A>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_field_method_set<M, A>(&mut self, name: impl Into<String>, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<()> + MaybeSend + 'static,
        A: FromLua,
@@ -415,7 +414,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
        self.raw.field_setters.push((name, callback));
    }

-    fn add_field_function_get<F, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_field_function_get<F, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(&Lua, AnyUserData) -> Result<R> + MaybeSend + 'static,
        R: IntoLua,
@@ -425,7 +424,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
        self.raw.field_getters.push((name, callback));
    }

-    fn add_field_function_set<F, A>(&mut self, name: impl Into<StdString>, mut function: F)
+    fn add_field_function_set<F, A>(&mut self, name: impl Into<String>, mut function: F)
    where
        F: FnMut(&Lua, AnyUserData, A) -> Result<()> + MaybeSend + 'static,
        A: FromLua,
@@ -435,7 +434,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
        self.raw.field_setters.push((name, callback));
    }

-    fn add_meta_field<V>(&mut self, name: impl Into<StdString>, value: V)
+    fn add_meta_field<V>(&mut self, name: impl Into<String>, value: V)
    where
        V: IntoLua + 'static,
    {
@@ -445,7 +444,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
        self.raw.meta_fields.push((name, field));
    }

-    fn add_meta_field_with<F, R>(&mut self, name: impl Into<StdString>, f: F)
+    fn add_meta_field_with<F, R>(&mut self, name: impl Into<String>, f: F)
    where
        F: FnOnce(&Lua) -> Result<R> + 'static,
        R: IntoLua,
@@ -458,7 +457,7 @@ impl<T> UserDataFields<T> for UserDataRegistry<T> {
 }

 impl<T> UserDataMethods<T> for UserDataRegistry<T> {
-    fn add_method<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_method<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -469,7 +468,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.methods.push((name, callback));
    }

-    fn add_method_mut<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_method_mut<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -481,7 +480,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    }

    #[cfg(feature = "async")]
-    fn add_async_method<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_async_method<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -495,7 +494,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    }

    #[cfg(feature = "async")]
-    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_async_method_mut<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -508,7 +507,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.async_methods.push((name, callback));
    }

-    fn add_function<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_function<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -519,7 +518,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.methods.push((name, callback));
    }

-    fn add_function_mut<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_function_mut<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -531,7 +530,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    }

    #[cfg(feature = "async")]
-    fn add_async_function<F, A, FR, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_async_function<F, A, FR, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -543,7 +542,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.async_methods.push((name, callback));
    }

-    fn add_meta_method<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_meta_method<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: Fn(&Lua, &T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -554,7 +553,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.meta_methods.push((name, callback));
    }

-    fn add_meta_method_mut<M, A, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_meta_method_mut<M, A, R>(&mut self, name: impl Into<String>, method: M)
    where
        M: FnMut(&Lua, &mut T, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -566,7 +565,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    }

    #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
-    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_async_meta_method<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRef<T>, A) -> MR + MaybeSend + 'static,
@@ -580,7 +579,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    }

    #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
-    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl Into<StdString>, method: M)
+    fn add_async_meta_method_mut<M, A, MR, R>(&mut self, name: impl Into<String>, method: M)
    where
        T: 'static,
        M: Fn(Lua, UserDataRefMut<T>, A) -> MR + MaybeSend + 'static,
@@ -593,7 +592,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.async_meta_methods.push((name, callback));
    }

-    fn add_meta_function<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_meta_function<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -604,7 +603,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
        self.raw.meta_methods.push((name, callback));
    }

-    fn add_meta_function_mut<F, A, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_meta_function_mut<F, A, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -616,7 +615,7 @@ impl<T> UserDataMethods<T> for UserDataRegistry<T> {
    }

    #[cfg(all(feature = "async", not(any(feature = "lua51", feature = "luau"))))]
-    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl Into<StdString>, function: F)
+    fn add_async_meta_function<F, A, FR, R>(&mut self, name: impl Into<String>, function: F)
    where
        F: Fn(Lua, A) -> FR + MaybeSend + 'static,
        A: FromLuaMulti,
@@ -655,6 +654,12 @@ macro_rules! lua_userdata_impl {
 // A special proxy object for UserData
 pub(crate) struct UserDataProxy<T>(pub(crate) PhantomData<T>);

+// `UserDataProxy` holds no real `T` value, only a type marker, so it is always safe to send/share.
+#[cfg(feature = "send")]
+unsafe impl<T> Send for UserDataProxy<T> {}
+#[cfg(feature = "send")]
+unsafe impl<T> Sync for UserDataProxy<T> {}
+
 lua_userdata_impl!(UserDataProxy<T>);

 #[cfg(all(feature = "userdata-wrappers", not(feature = "send")))]
@@ -1,6 +1,4 @@
 use std::any::TypeId;
-use std::cell::Cell;
-use std::marker::PhantomData;
 use std::os::raw::c_int;
 use std::ptr;

@@ -11,35 +9,6 @@ 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.
-// It uses leaked specialization feature from stdlib.
-struct IsSync<'a, T> {
-    is_sync: &'a Cell<bool>,
-    _marker: PhantomData<T>,
-}
-
-impl<T> Clone for IsSync<'_, T> {
-    fn clone(&self) -> Self {
-        self.is_sync.set(false);
-        IsSync {
-            is_sync: self.is_sync,
-            _marker: PhantomData,
-        }
-    }
-}
-
-impl<T: Sync> Copy for IsSync<'_, T> {}
-
-pub(crate) fn is_sync<T>() -> bool {
-    let is_sync = Cell::new(true);
-    let _ = [IsSync::<T> {
-        is_sync: &is_sync,
-        _marker: PhantomData,
-    }]
-    .clone();
-    is_sync.get()
-}
-
 // Userdata type hints,  used to match types of wrapped userdata
 #[derive(Clone, Copy)]
 pub(crate) struct TypeIdHints {
@@ -2,15 +2,15 @@ use std::any::Any;
 use std::fmt::Write as _;
 use std::mem::MaybeUninit;
 use std::os::raw::{c_int, c_void};
-use std::panic::{catch_unwind, resume_unwind, AssertUnwindSafe};
+use std::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
 use std::ptr;
 use std::sync::Arc;

 use crate::error::{Error, Result};
 use crate::memory::MemoryState;
 use crate::util::{
-    check_stack, get_internal_userdata, init_internal_metatable, push_internal_userdata, push_string,
-    push_table, rawset_field, to_string, TypeKey, DESTRUCTED_USERDATA_METATABLE,
+    DESTRUCTED_USERDATA_METATABLE, TypeKey, check_stack, get_internal_userdata, init_internal_metatable,
+    push_internal_userdata, push_string, push_table, rawset_field, to_string,
 };

 static WRAPPED_FAILURE_TYPE_KEY: u8 = 0;
@@ -197,7 +197,7 @@ where
    F: FnOnce(*mut ffi::lua_State) -> R,
    R: Copy,
 {
-    struct Params<F, R: Copy> {
+    struct Params<F, R> {
        function: Option<F>,
        result: MaybeUninit<R>,
        nresults: c_int,
@@ -6,16 +6,16 @@ use std::{ptr, slice, str};
 use crate::error::{Error, Result};

 pub(crate) use error::{
-    error_traceback, error_traceback_thread, init_error_registry, pop_error, protect_lua_call,
-    protect_lua_closure, WrappedFailure,
+    WrappedFailure, error_traceback, error_traceback_thread, init_error_registry, pop_error,
+    protect_lua_call, protect_lua_closure,
 };
 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::{
-    get_destructed_userdata_metatable, get_internal_metatable, get_internal_userdata, get_userdata,
-    init_internal_metatable, push_internal_userdata, push_userdata, take_userdata,
-    DESTRUCTED_USERDATA_METATABLE,
+    DESTRUCTED_USERDATA_METATABLE, get_destructed_userdata_metatable, get_internal_metatable,
+    get_internal_userdata, get_userdata, init_internal_metatable, push_internal_userdata, push_userdata,
+    take_userdata,
 };

 #[cfg(not(feature = "luau"))]
@@ -264,11 +264,7 @@ pub(crate) unsafe fn get_main_state(state: *mut ffi::lua_State) -> Option<*mut f
        // Check the current state first
        let is_main_state = ffi::lua_pushthread(state) == 1;
        ffi::lua_pop(state, 1);
-        if is_main_state {
-            Some(state)
-        } else {
-            None
-        }
+        if is_main_state { Some(state) } else { None }
    }
    #[cfg(feature = "luau")]
    Some(ffi::lua_mainthread(state))
@@ -196,7 +196,7 @@ fn unquote_string<'a>(path: &'a str, chars: &mut Peekable<CharIndices<'a>>) -> R

 #[cfg(test)]
 mod tests {
-    use super::{parse_path, PathKey};
+    use super::{PathKey, parse_path};

    #[test]
    fn test_parse_path() {
@@ -3,7 +3,7 @@ use std::{mem, ptr};

 use crate::error::Result;
 use crate::userdata::collect_userdata;
-use crate::util::{check_stack, get_metatable_ptr, push_table, rawset_field, TypeKey};
+use crate::util::{TypeKey, check_stack, get_metatable_ptr, push_table, rawset_field};

 // Pushes the userdata and attaches a metatable with __gc method.
 // Internally uses 3 stack spaces, does not call checkstack.
@@ -1,19 +1,18 @@
 use std::cmp::Ordering;
 use std::collections::HashSet;
 use std::os::raw::c_void;
-use std::string::String as StdString;
 use std::{fmt, ptr, str};

 use num_traits::FromPrimitive;

 use crate::error::{Error, Result};
 use crate::function::Function;
-use crate::string::{BorrowedStr, String};
+use crate::string::{BorrowedStr, LuaString};
 use crate::table::Table;
 use crate::thread::Thread;
 use crate::types::{Integer, LightUserData, Number, ValueRef};
 use crate::userdata::AnyUserData;
-use crate::util::{check_stack, StackGuard};
+use crate::util::{StackGuard, check_stack};

 #[cfg(feature = "serde")]
 use {
@@ -50,7 +49,7 @@ pub enum Value {
    /// An interned string, managed by Lua.
    ///
    /// Unlike Rust strings, Lua strings may not be valid UTF-8.
-    String(String),
+    String(LuaString),
    /// Reference to a Lua table.
    Table(Table),
    /// Reference to a Lua function (or closure).
@@ -129,7 +128,7 @@ impl Value {
    #[inline]
    pub fn to_pointer(&self) -> *const c_void {
        match self {
-            Value::String(String(vref)) => {
+            Value::String(LuaString(vref)) => {
                // In Lua < 5.4 (excluding Luau), string pointers are NULL
                // Use alternative approach
                let lua = vref.lua.lock();
@@ -151,8 +150,8 @@ impl Value {
    ///
    /// This might invoke the `__tostring` metamethod for non-primitive types (eg. tables,
    /// functions).
-    pub fn to_string(&self) -> Result<StdString> {
-        unsafe fn invoke_to_string(vref: &ValueRef) -> Result<StdString> {
+    pub fn to_string(&self) -> Result<String> {
+        unsafe fn invoke_tostring(vref: &ValueRef) -> Result<String> {
            let lua = vref.lua.lock();
            let state = lua.state();
            let _guard = StackGuard::new(state);
@@ -162,7 +161,7 @@ impl Value {
            protect_lua!(state, 1, 1, fn(state) {
                ffi::luaL_tolstring(state, -1, ptr::null_mut());
            })?;
-            Ok(String(lua.pop_ref()).to_str()?.to_string())
+            Ok(LuaString(lua.pop_ref()).to_str()?.to_string())
        }

        match self {
@@ -179,9 +178,9 @@ impl Value {
            | Value::Function(Function(vref))
            | Value::Thread(Thread(vref, ..))
            | Value::UserData(AnyUserData(vref))
-            | Value::Other(vref) => unsafe { invoke_to_string(vref) },
+            | Value::Other(vref) => unsafe { invoke_tostring(vref) },
            #[cfg(feature = "luau")]
-            Value::Buffer(crate::Buffer(vref)) => unsafe { invoke_to_string(vref) },
+            Value::Buffer(crate::Buffer(vref)) => unsafe { invoke_tostring(vref) },
            Value::Error(err) => Ok(err.to_string()),
        }
    }
@@ -336,17 +335,17 @@ impl Value {
        self.as_number()
    }

-    /// Returns `true` if the value is a Lua [`String`].
+    /// Returns `true` if the value is a [`LuaString`].
    #[inline]
    pub fn is_string(&self) -> bool {
        self.as_string().is_some()
    }

-    /// Cast the value to Lua [`String`].
+    /// Cast the value to a [`LuaString`].
    ///
-    /// If the value is a Lua [`String`], returns it or `None` otherwise.
+    /// If the value is a [`LuaString`], returns it or `None` otherwise.
    #[inline]
-    pub fn as_string(&self) -> Option<&String> {
+    pub fn as_string(&self) -> Option<&LuaString> {
        match self {
            Value::String(s) => Some(s),
            _ => None,
@@ -355,26 +354,26 @@ impl Value {

    /// Cast the value to [`BorrowedStr`].
    ///
-    /// If the value is a Lua [`String`], try to convert it to [`BorrowedStr`] or return `None`
+    /// If the value is a [`LuaString`], 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`].
+    /// Cast the value to [`String`].
    ///
-    /// If the value is a Lua [`String`], converts it to [`StdString`] or returns `None` otherwise.
+    /// If the value is a [`LuaString`], converts it to [`String`] 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> {
+    pub fn as_string_lossy(&self) -> Option<String> {
        self.as_string().map(|s| s.to_string_lossy())
    }

@@ -562,15 +561,7 @@ impl Value {
            t @ Value::Table(_) => write!(fmt, "table: {:?}", t.to_pointer()),
            f @ Value::Function(_) => write!(fmt, "function: {:?}", f.to_pointer()),
            t @ Value::Thread(_) => write!(fmt, "thread: {:?}", t.to_pointer()),
-            u @ Value::UserData(ud) => {
-                // Try `__name/__type` first then `__tostring`
-                let name = ud.type_name().ok().flatten();
-                let s = name
-                    .map(|name| format!("{name}: {:?}", u.to_pointer()))
-                    .or_else(|| u.to_string().ok())
-                    .unwrap_or_else(|| format!("userdata: {:?}", u.to_pointer()));
-                write!(fmt, "{s}")
-            }
+            Value::UserData(ud) => ud.fmt_pretty(fmt),
            #[cfg(feature = "luau")]
            buf @ Value::Buffer(_) => write!(fmt, "buffer: {:?}", buf.to_pointer()),
            Value::Error(e) if recursive => write!(fmt, "{e:?}"),
@@ -1,6 +1,5 @@
 #![cfg(feature = "async")]

-use std::string::String as StdString;
 use std::sync::Arc;
 use std::time::Duration;

@@ -8,7 +7,7 @@ use futures_util::stream::TryStreamExt;
 use tokio::sync::Mutex;

 use mlua::{
-    Error, Function, Lua, LuaOptions, MultiValue, ObjectLike, Result, StdLib, Table, ThreadStatus, UserData,
+    Error, Function, Lua, LuaOptions, MultiValue, ObjectLike, Result, StdLib, Table, UserData,
    UserDataMethods, UserDataRef, Value,
 };

@@ -40,9 +39,9 @@ async fn test_async_function() -> Result<()> {
 async fn test_async_function_wrap() -> Result<()> {
    let lua = Lua::new();

-    let f = Function::wrap_async(|s: StdString| async move {
+    let f = Function::wrap_async(|s: String| async move {
        tokio::task::yield_now().await;
-        Ok(s)
+        Ok::<_, Error>(s)
    });
    lua.globals().set("f", f)?;
    let res: String = lua.load(r#"f("hello")"#).eval_async().await?;
@@ -68,7 +67,7 @@ async fn test_async_function_wrap() -> Result<()> {
 async fn test_async_function_wrap_raw() -> Result<()> {
    let lua = Lua::new();

-    let f = Function::wrap_raw_async(|s: StdString| async move {
+    let f = Function::wrap_raw_async(|s: String| async move {
        tokio::task::yield_now().await;
        s
    });
@@ -715,7 +714,7 @@ fn test_async_yield_with() -> Result<()> {
    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);
+    assert!(thread.is_finished());

    Ok(())
 }
@@ -1,3 +1,4 @@
+#[cfg(not(target_os = "wasi"))]
 use std::{fs, io};

 use mlua::{Chunk, ChunkMode, Lua, Result};
@@ -85,7 +86,7 @@ fn test_chunk_macro() -> Result<()> {
    data.raw_set("num", 1)?;

    let ud = mlua::AnyUserData::wrap("hello");
-    let f = mlua::Function::wrap(|| Ok(()));
+    let f = mlua::Function::wrap(|| Ok::<_, mlua::Error>(()));

    lua.globals().set("g", 123)?;

@@ -1,28 +1,28 @@
-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
+error[E0277]: the type `UnsafeCell<mlua::state::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<mlua::state::raw::RawLua>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
+  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<mlua::state::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 `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>`
+  = help: within `Lua`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<mlua::state::RawLua>`
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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>>`
+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::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>>>`
+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::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>>`
+note: required because it appears within the type `Arc<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::RawLua>>`
 --> $RUST/alloc/src/sync.rs
  |
  | pub struct Arc<
@@ -63,22 +63,22 @@ note: required because it appears within the type `lock_api::remutex::RawReentra
  |
  | 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>`
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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>>`
+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::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>>>`
+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::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>>`
+note: required because it appears within the type `Arc<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::RawLua>>`
 --> $RUST/alloc/src/sync.rs
  |
  | pub struct Arc<
@@ -1,24 +1,24 @@
-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
+error[E0277]: the type `UnsafeCell<mlua::state::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<mlua::state::raw::RawLua>` may contain interior mutability and a reference may not be safely transferable across a catch_unwind boundary
+  |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<mlua::state::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 `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>`
+  = help: within `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::RawLua>>`, the trait `RefUnwindSafe` is not implemented for `UnsafeCell<mlua::state::RawLua>`
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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>>`
+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::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>>`
+  = note: required for `NonNull<alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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::RawLua>>`
 --> $RUST/alloc/src/sync.rs
  |
  | pub struct Weak<
@@ -57,7 +57,7 @@ error[E0277]: the type `UnsafeCell<usize>` may contain interior mutability and a
  |     |
  |     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>`
+  = help: within `alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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
  |
@@ -68,18 +68,18 @@ note: required because it appears within the type `lock_api::remutex::RawReentra
  |
  | 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>`
+note: required because it appears within the type `lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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>>`
+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::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>>`
+  = note: required for `NonNull<alloc::sync::ArcInner<lock_api::remutex::ReentrantMutex<parking_lot::raw_mutex::RawMutex, parking_lot::remutex::RawThreadId, mlua::state::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::RawLua>>`
 --> $RUST/alloc/src/sync.rs
  |
  | pub struct Weak<
@@ -49,7 +49,7 @@ fn test_string_from_lua() -> Result<()> {
    let lua = Lua::new();

    // From stack
-    let f = lua.create_function(|_, s: mlua::String| Ok(s))?;
+    let f = lua.create_function(|_, s: mlua::LuaString| Ok(s))?;
    let s = f.call::<String>("hello, world!")?;
    assert_eq!(s, "hello, world!");

@@ -708,9 +708,10 @@ fn test_either_from_lua() -> Result<()> {
                },
                err => panic!("expected `Error::BadArgument`, got {err:?}"),
            }
-            assert!(err
-                .to_string()
-                .starts_with("bad argument #1: error converting Lua string to Either<i32, Table>"),);
+            assert!(
+                err.to_string()
+                    .starts_with("bad argument #1: error converting Lua string to Either<i32, Table>"),
+            );
        }
        err => panic!("expected `Error::CallbackError`, got {err:?}"),
    }
@@ -736,15 +737,18 @@ fn test_char_from_lua() -> Result<()> {
    assert_eq!(lua.convert::<char>("A")?, 'A');
    assert_eq!(lua.convert::<char>(65)?, 'A');
    assert_eq!(lua.convert::<char>(128175)?, '💯');
-    assert!(lua
-        .convert::<char>(5456324)
-        .is_err_and(|e| e.to_string().contains("integer out of range")));
-    assert!(lua
-        .convert::<char>("hello")
-        .is_err_and(|e| e.to_string().contains("expected string to have exactly one char")));
-    assert!(lua
-        .convert::<char>(HashMap::<String, String>::new())
-        .is_err_and(|e| e.to_string().contains("expected string or integer")));
+    assert!(
+        lua.convert::<char>(5456324)
+            .is_err_and(|e| e.to_string().contains("integer out of range"))
+    );
+    assert!(
+        lua.convert::<char>("hello")
+            .is_err_and(|e| e.to_string().contains("expected string to have exactly one char"))
+    );
+    assert!(
+        lua.convert::<char>(HashMap::<String, String>::new())
+            .is_err_and(|e| e.to_string().contains("expected string or integer"))
+    );

    Ok(())
 }
@@ -77,6 +77,19 @@ fn test_error_chain() -> Result<()> {
    Ok(())
 }

+#[test]
+fn test_external_error() {
+    // `Error::external` should preserve `mlua::Error`
+    let runtime_err = Error::runtime("test error");
+    let converted = Error::external(runtime_err);
+    assert!(matches!(converted, Error::RuntimeError(ref msg) if msg == "test error"));
+
+    // Other errors should become `ExternalError`
+    let converted = Error::external(io::Error::other("other error"));
+    assert!(matches!(converted, Error::ExternalError(_)));
+    assert!(converted.downcast_ref::<io::Error>().is_some());
+}
+
 #[cfg(feature = "anyhow")]
 #[test]
 fn test_error_anyhow() -> Result<()> {
@@ -1,4 +1,7 @@
-use mlua::{Error, Function, Lua, Result, String, Table, Variadic};
+use std::fmt;
+use std::result::Result as StdResult;
+
+use mlua::{Error, Function, Lua, LuaString, Result, Table, Variadic};

 #[test]
 fn test_function_call() -> Result<()> {
@@ -267,7 +270,7 @@ fn test_function_coverage() -> Result<()> {

    assert_eq!(
        report[0],
-        mlua::CoverageInfo {
+        mlua::function::CoverageInfo {
            function: None,
            line_defined: 1,
            depth: 0,
@@ -276,7 +279,7 @@ fn test_function_coverage() -> Result<()> {
    );
    assert_eq!(
        report[1],
-        mlua::CoverageInfo {
+        mlua::function::CoverageInfo {
            function: Some("abc".into()),
            line_defined: 4,
            depth: 1,
@@ -285,7 +288,7 @@ fn test_function_coverage() -> Result<()> {
    );
    assert_eq!(
        report[2],
-        mlua::CoverageInfo {
+        mlua::function::CoverageInfo {
            function: None,
            line_defined: 12,
            depth: 1,
@@ -294,7 +297,7 @@ fn test_function_coverage() -> Result<()> {
    );
    assert_eq!(
        report[3],
-        mlua::CoverageInfo {
+        mlua::function::CoverageInfo {
            function: None,
            line_defined: 13,
            depth: 2,
@@ -343,7 +346,7 @@ fn test_function_deep_clone() -> Result<()> {
 fn test_function_wrap() -> Result<()> {
    let lua = Lua::new();

-    let f = Function::wrap(|s: String, n| Ok(s.to_str().unwrap().repeat(n)));
+    let f = Function::wrap(|s: LuaString, n| Ok::<_, Error>(s.to_str().unwrap().repeat(n)));
    lua.globals().set("f", f)?;
    lua.load(r#"assert(f("hello", 2) == "hellohello")"#)
        .exec()
@@ -361,11 +364,40 @@ fn test_function_wrap() -> Result<()> {
    .exec()
    .unwrap();

+    // Return external error
+    #[derive(Debug)]
+    struct MyError(String);
+    impl fmt::Display for MyError {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            write!(f, "MyError: {}", self.0)
+        }
+    }
+    impl std::error::Error for MyError {}
+
+    let fext = Function::wrap(|s: String| -> StdResult<String, MyError> {
+        if s == "bad" {
+            return Err(MyError("bad input".into()));
+        }
+        Ok(format!("ok: {s}"))
+    });
+    lua.globals().set("fext", fext)?;
+    lua.load(r#"assert(fext("hello") == "ok: hello")"#)
+        .exec()
+        .unwrap();
+    lua.load(
+        r#"
+        local ok, err = pcall(fext, "bad")
+        assert(not ok and tostring(err):find("MyError: bad input"))
+    "#,
+    )
+    .exec()
+    .unwrap();
+
    // Mutable callback
    let mut i = 0;
    let fmut = Function::wrap_mut(move || {
        i += 1;
-        Ok(i)
+        Ok::<_, Error>(i)
    });
    lua.globals().set("fmut", fmut)?;
    lua.load(r#"fmut(); fmut(); assert(fmut() == 3)"#).exec().unwrap();
@@ -385,7 +417,7 @@ fn test_function_wrap() -> Result<()> {
    // Check recursive mut callback error
    let fmut = Function::wrap_mut(|f: Function| match f.call::<()>(&f) {
        Err(Error::CallbackError { cause, .. }) => match cause.as_ref() {
-            Error::RecursiveMutCallback { .. } => Ok(()),
+            Error::RecursiveMutCallback { .. } => Ok::<_, Error>(()),
            other => panic!("incorrect result: {other:?}"),
        },
        other => panic!("incorrect result: {other:?}"),
@@ -3,7 +3,8 @@
 use std::sync::atomic::{AtomicI64, Ordering};
 use std::sync::{Arc, Mutex};

-use mlua::{DebugEvent, Error, HookTriggers, Lua, Result, ThreadStatus, Value, VmState};
+use mlua::debug::DebugEvent;
+use mlua::{Error, HookTriggers, Lua, Result, Value, VmState};

 #[test]
 fn test_hook_triggers() {
@@ -280,14 +281,14 @@ fn test_hook_yield() -> Result<()> {
        assert!(co.resume::<()>(()).is_ok());
        assert!(co.resume::<()>(()).is_ok());
        assert!(co.resume::<()>(()).is_ok());
-        assert!(co.status() == ThreadStatus::Finished);
+        assert!(co.is_finished());
    }
    #[cfg(any(feature = "lua51", feature = "lua52", feature = "luajit"))]
    {
        assert!(
            matches!(co.resume::<()>(()), Err(Error::RuntimeError(err)) if err.contains("attempt to yield from a hook"))
        );
-        assert!(co.status() == ThreadStatus::Error);
+        assert!(co.is_error());
    }

    Ok(())
@@ -320,7 +321,7 @@ fn test_global_hook() -> Result<()> {
    thread.resume::<()>(()).unwrap();
    lua.remove_global_hook();
    thread.resume::<()>(()).unwrap();
-    assert_eq!(thread.status(), ThreadStatus::Finished);
+    assert!(thread.is_finished());
    assert_eq!(counter.load(Ordering::Relaxed), 3);

    Ok(())
@@ -3,11 +3,11 @@
 use std::cell::Cell;
 use std::fmt::Debug;
 use std::os::raw::c_void;
-use std::sync::atomic::{AtomicBool, AtomicPtr, AtomicU64, Ordering};
 use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, AtomicPtr, AtomicU64, Ordering};

 use mlua::{
-    Compiler, Error, Function, Lua, LuaOptions, Result, StdLib, Table, ThreadStatus, Value, Vector, VmState,
+    Compiler, Error, Function, Lua, LuaOptions, ObjectLike, Result, StdLib, Table, Value, Vector, VmState,
 };

 #[test]
@@ -324,11 +324,11 @@ fn test_interrupts() -> Result<()> {
        .into_function()?,
    )?;
    co.resume::<()>(())?;
-    assert_eq!(co.status(), ThreadStatus::Resumable);
+    assert!(co.is_resumable());
    let result: i32 = co.resume(())?;
    assert_eq!(result, 6);
    assert_eq!(yield_count.load(Ordering::Relaxed), 7);
-    assert_eq!(co.status(), ThreadStatus::Finished);
+    assert!(co.is_finished());

    // Test no yielding at non-yieldable points
    yield_count.store(0, Ordering::Relaxed);
@@ -535,5 +535,23 @@ fn test_heap_dump() -> Result<()> {
    Ok(())
 }

+#[test]
+fn test_integer64_type() -> Result<()> {
+    let lua = Lua::new();
+
+    _ = Lua::set_fflag("LuauIntegerType", true);
+
+    let integer_lib = lua.globals().get::<Table>("integer")?;
+    let n = integer_lib.call_function::<i64>("create", 42)?;
+    assert_eq!(n, 42);
+
+    let n: i64 = lua.load("return 42i").eval()?;
+    assert_eq!(n, 42);
+    let n: i64 = lua.load("return -42i").eval()?;
+    assert_eq!(n, -42);
+
+    Ok(())
+}
+
 #[path = "luau/require.rs"]
 mod require;
@@ -1,7 +1,8 @@
 use std::io::Result as IoResult;
 use std::result::Result as StdResult;

-use mlua::{Error, FromLua, IntoLua, Lua, MultiValue, NavigateError, Require, Result, TextRequirer, Value};
+use mlua::luau::{FsRequirer, NavigateError, Require};
+use mlua::{Error, FromLua, IntoLua, Lua, MultiValue, Result, Value};

 fn run_require(lua: &Lua, path: impl IntoLua) -> Result<Value> {
    lua.load(r#"return require(...)"#).call(path)
@@ -42,8 +43,10 @@ fn test_require_errors() {
    // Pass non-string to require
    let res = run_require(&lua, true);
    assert!(res.is_err());
-    assert!((res.unwrap_err().to_string())
-        .contains("bad argument #1 to 'require' (string expected, got boolean)"));
+    assert!(
+        (res.unwrap_err().to_string())
+            .contains("bad argument #1 to 'require' (string expected, got boolean)")
+    );

    // Require from loadstring
    let res = lua
@@ -63,7 +66,7 @@ fn test_require_errors() {
    assert!((res.unwrap_err().to_string()).contains("@ is not a valid alias"));

    // Test throwing mlua::Error
-    struct MyRequire(TextRequirer);
+    struct MyRequire(FsRequirer);

    impl Require for MyRequire {
        fn is_require_allowed(&self, chunk_name: &str) -> bool {
@@ -107,9 +110,7 @@ fn test_require_errors() {
        }
    }

-    let require = lua
-        .create_require_function(MyRequire(TextRequirer::new()))
-        .unwrap();
+    let require = lua.create_require_function(MyRequire(FsRequirer::new())).unwrap();
    lua.globals().set("require", require).unwrap();
    let res = lua.load(r#"return require('./a/relative/path')"#).exec();
    assert!((res.unwrap_err().to_string()).contains("test error"));
@@ -169,8 +170,10 @@ fn test_require_without_config() {
        "./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)"));
+    assert!(
+        (res.unwrap_err().to_string())
+            .contains("could not resolve child component \"dependency\" (ambiguous)")
+    );

    // RequireWithDirectoryAmbiguity
    let res = run_require(
@@ -178,8 +181,10 @@ fn test_require_without_config() {
        "./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)"));
+    assert!(
+        (res.unwrap_err().to_string())
+            .contains("could not resolve child component \"dependency\" (ambiguous)")
+    );

    // CheckCachedResult
    let res = run_require(&lua, "./tests/luau/require/without_config/validate_cache").unwrap();
@@ -1,6 +1,10 @@
 use std::sync::Arc;

-use mlua::{Error, GCMode, Lua, Result, UserData};
+use mlua::state::{GcIncParams, GcMode};
+use mlua::{Error, Lua, Result, UserData};
+
+#[cfg(any(feature = "lua54", feature = "lua55"))]
+use mlua::state::GcGenParams;

 #[test]
 fn test_memory_limit() -> Result<()> {
@@ -74,8 +78,14 @@ fn test_gc_control() -> Result<()> {

    #[cfg(any(feature = "lua55", feature = "lua54"))]
    {
-        assert_eq!(lua.gc_gen(0, 0), GCMode::Incremental);
-        assert_eq!(lua.gc_inc(0, 0, 0), GCMode::Generational);
+        assert!(matches!(
+            lua.gc_set_mode(GcMode::Generational(GcGenParams::default())),
+            GcMode::Incremental(_)
+        ));
+        assert!(matches!(
+            lua.gc_set_mode(GcMode::Incremental(GcIncParams::default())),
+            GcMode::Generational(_)
+        ));
    }

    #[cfg(any(
@@ -93,7 +103,17 @@ fn test_gc_control() -> Result<()> {
        assert!(lua.gc_is_running());
    }

-    assert_eq!(lua.gc_inc(200, 100, 13), GCMode::Incremental);
+    assert!(matches!(
+        lua.gc_set_mode(GcMode::Incremental({
+            let p = GcIncParams::default().step_multiplier(100);
+            #[cfg(not(feature = "luau"))]
+            let p = p.pause(200);
+            #[cfg(feature = "luau")]
+            let p = p.goal(200);
+            p
+        })),
+        GcMode::Incremental(_)
+    ));

    struct MyUserdata(#[allow(unused)] Arc<()>);
    impl UserData for MyUserdata {}
@@ -1,4 +1,6 @@
-use mlua::{Error, ExternalError, Integer, IntoLuaMulti, Lua, MultiValue, Result, String, Value, Variadic};
+use mlua::{
+    Error, ExternalError, Integer, IntoLuaMulti, Lua, LuaString, MultiValue, Result, Value, Variadic,
+};

 #[test]
 fn test_result_conversions() -> Result<()> {
@@ -81,7 +83,7 @@ fn test_multivalue_by_ref() -> Result<()> {
        Value::Boolean(true),
    ]);

-    let f = lua.create_function(|_, (i, s, b): (i32, String, bool)| {
+    let f = lua.create_function(|_, (i, s, b): (i32, LuaString, bool)| {
        assert_eq!(i, 3);
        assert_eq!(s.to_str()?, "hello");
        assert_eq!(b, true);
@@ -1,10 +1,9 @@
 use std::cell::Cell;
 use std::rc::Rc;
-use std::string::String as StdString;
 use std::sync::Arc;

 use mlua::{
-    AnyUserData, Error, Function, Lua, MetaMethod, ObjectLike, Result, String, UserData, UserDataFields,
+    AnyUserData, Error, Function, Lua, LuaString, MetaMethod, ObjectLike, Result, UserData, UserDataFields,
    UserDataMethods, UserDataRegistry,
 };

@@ -437,15 +436,15 @@ fn test_scope_userdata_ref_mut() -> Result<()> {
 fn test_scope_any_userdata() -> Result<()> {
    let lua = Lua::new();

-    fn register(reg: &mut UserDataRegistry<&mut StdString>) {
-        reg.add_method_mut("push", |_, this, s: String| {
+    fn register(reg: &mut UserDataRegistry<&mut String>) {
+        reg.add_method_mut("push", |_, this, s: LuaString| {
            this.push_str(&s.to_str()?);
            Ok(())
        });
        reg.add_meta_method("__tostring", |_, data, ()| Ok((*data).clone()));
    }

-    let mut data = StdString::from("foo");
+    let mut data = String::from("foo");
    lua.scope(|scope| {
        let ud = scope.create_any_userdata(&mut data, register)?;
        lua.globals().set("ud", ud)?;
@@ -527,11 +526,11 @@ fn test_scope_any_userdata_ref_mut() -> Result<()> {
 fn test_scope_destructors() -> Result<()> {
    let lua = Lua::new();

-    lua.register_userdata_type::<Arc<StdString>>(|reg| {
+    lua.register_userdata_type::<Arc<String>>(|reg| {
        reg.add_meta_method("__tostring", |_, data, ()| Ok(data.to_string()));
    })?;

-    let arc_str = Arc::new(StdString::from("foo"));
+    let arc_str = Arc::new(String::from("foo"));

    let ud = lua.create_any_userdata(arc_str.clone())?;
    lua.scope(|scope| {
@@ -544,7 +543,7 @@ fn test_scope_destructors() -> Result<()> {

    // Try destructing the userdata while it's borrowed
    let ud = lua.create_any_userdata(arc_str.clone())?;
-    ud.borrow_scoped::<Arc<StdString>, _>(|arc_str| {
+    ud.borrow_scoped::<Arc<String>, _>(|arc_str| {
        assert_eq!(arc_str.as_str(), "foo");
        lua.scope(|scope| {
            scope.add_destructor(|| {
@@ -1,58 +1,14 @@
 #![cfg(feature = "send")]

-use std::cell::UnsafeCell;
-use std::marker::PhantomData;
-use std::string::String as StdString;
-
-use mlua::{AnyUserData, Error, Lua, ObjectLike, Result, UserData, UserDataMethods, UserDataRef};
-use static_assertions::{assert_impl_all, assert_not_impl_all};
-
-#[test]
-fn test_userdata_multithread_access_send_only() -> Result<()> {
-    let lua = Lua::new();
-
-    // This type is `Send` but not `Sync`.
-    struct MyUserData(StdString, PhantomData<UnsafeCell<()>>);
-    assert_impl_all!(MyUserData: Send);
-    assert_not_impl_all!(MyUserData: Sync);
-
-    impl UserData for MyUserData {
-        fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
-            methods.add_method("method", |lua, this, ()| {
-                let ud = lua.globals().get::<AnyUserData>("ud")?;
-                assert_eq!(ud.call_method::<String>("method2", ())?, "method2");
-                Ok(this.0.clone())
-            });
-
-            methods.add_method("method2", |_, _, ()| Ok("method2"));
-        }
-    }
-
-    lua.globals()
-        .set("ud", MyUserData("hello".to_string(), PhantomData))?;
-
-    // We acquired the exclusive reference.
-    let ud = lua.globals().get::<UserDataRef<MyUserData>>("ud")?;
-
-    std::thread::scope(|s| {
-        s.spawn(|| {
-            let res = lua.globals().get::<UserDataRef<MyUserData>>("ud");
-            assert!(matches!(res, Err(Error::UserDataBorrowError)));
-        });
-    });
-
-    drop(ud);
-    lua.load("ud:method()").exec().unwrap();
-
-    Ok(())
-}
+use mlua::{AnyUserData, Lua, ObjectLike, Result, UserData, UserDataMethods, UserDataRef};
+use static_assertions::assert_impl_all;

 #[test]
 fn test_userdata_multithread_access_sync() -> Result<()> {
    let lua = Lua::new();

    // This type is `Send` and `Sync`.
-    struct MyUserData(StdString);
+    struct MyUserData(String);
    assert_impl_all!(MyUserData: Send, Sync);

    impl UserData for MyUserData {
@@ -75,13 +31,11 @@ fn test_userdata_multithread_access_sync() -> Result<()> {
    std::thread::scope(|s| {
        s.spawn(|| {
            // Getting another shared reference for `Sync` type is allowed.
-            // FIXME: does not work due to https://github.com/rust-lang/rust/pull/135634
-            // let _ = lua.globals().get::<UserDataRef<MyUserData>>("ud").unwrap();
+            let _ = lua.globals().get::<UserDataRef<MyUserData>>("ud").unwrap();
        });
    });

-    // FIXME: does not work due to https://github.com/rust-lang/rust/pull/135634
-    // lua.load("ud:method()").exec().unwrap();
+    lua.load("ud:method()").exec().unwrap();

    Ok(())
 }
@@ -1,11 +1,11 @@
 use std::borrow::Cow;
 use std::collections::HashSet;

-use mlua::{Lua, Result, String};
+use mlua::{Lua, LuaString, Result};

 #[test]
 fn test_string_compare() {
-    fn with_str<F: FnOnce(String)>(s: &str, f: F) {
+    fn with_str<F: FnOnce(LuaString)>(s: &str, f: F) {
        f(Lua::new().create_string(s).unwrap());
    }

@@ -42,9 +42,9 @@ fn test_string_views() -> Result<()> {
    .exec()?;

    let globals = lua.globals();
-    let ok: String = globals.get("ok")?;
-    let err: String = globals.get("err")?;
-    let empty: String = globals.get("empty")?;
+    let ok: LuaString = globals.get("ok")?;
+    let err: LuaString = globals.get("err")?;
+    let empty: LuaString = globals.get("empty")?;

    assert_eq!(ok.to_str()?, "null bytes are valid utf-8, wh\0 knew?");
    assert_eq!(ok.to_string_lossy(), "null bytes are valid utf-8, wh\0 knew?");
@@ -74,7 +74,7 @@ fn test_string_from_bytes() -> Result<()> {
 fn test_string_hash() -> Result<()> {
    let lua = Lua::new();

-    let set: HashSet<String> = lua.load(r#"{"hello", "world", "abc", 321}"#).eval()?;
+    let set: HashSet<LuaString> = lua.load(r#"{"hello", "world", "abc", 321}"#).eval()?;
    assert_eq!(set.len(), 4);
    assert!(set.contains(&lua.create_string("hello")?));
    assert!(set.contains(&lua.create_string("world")?));
@@ -133,13 +133,13 @@ fn test_string_display() -> Result<()> {
 fn test_string_wrap() -> Result<()> {
    let lua = Lua::new();

-    let s = String::wrap("hello, world");
+    let s = LuaString::wrap("hello, world");
    lua.globals().set("s", s)?;
-    assert_eq!(lua.globals().get::<String>("s")?, "hello, world");
+    assert_eq!(lua.globals().get::<LuaString>("s")?, "hello, world");

-    let s2 = String::wrap("hello, world (owned)".to_string());
+    let s2 = LuaString::wrap("hello, world (owned)".to_string());
    lua.globals().set("s2", s2)?;
-    assert_eq!(lua.globals().get::<String>("s2")?, "hello, world (owned)");
+    assert_eq!(lua.globals().get::<LuaString>("s2")?, "hello, world (owned)");

    Ok(())
 }
@@ -1,14 +1,13 @@
 use std::collections::HashMap;
 #[cfg(not(target_arch = "wasm32"))]
 use std::iter::FromIterator;
-use std::panic::{catch_unwind, AssertUnwindSafe};
-use std::string::String as StdString;
+use std::panic::{AssertUnwindSafe, catch_unwind};
 use std::sync::Arc;
 use std::{error, f32, f64, fmt};

 use mlua::{
-    ffi, ChunkMode, Error, ExternalError, Function, Lua, LuaOptions, Nil, Result, StdLib, String, Table,
-    UserData, Value, Variadic,
+    ChunkMode, Error, ExternalError, Function, Lua, LuaOptions, Nil, Result, StdLib, Table, UserData, Value,
+    Variadic, ffi,
 };

 #[test]
@@ -155,7 +154,7 @@ fn test_replace_globals() -> Result<()> {
    globals.set("foo", "bar")?;

    lua.set_globals(globals.clone())?;
-    let val = lua.load("return foo").eval::<StdString>()?;
+    let val = lua.load("return foo").eval::<String>()?;
    assert_eq!(val, "bar");

    // Updating globals in sandboxed Lua state is not allowed
@@ -398,7 +397,7 @@ fn test_error() -> Result<()> {
 fn test_panic() -> Result<()> {
    fn make_lua(options: LuaOptions) -> Result<Lua> {
        let lua = Lua::new_with(StdLib::ALL_SAFE, options)?;
-        let rust_panic_function = lua.create_function(|_, msg: Option<StdString>| -> Result<()> {
+        let rust_panic_function = lua.create_function(|_, msg: Option<String>| -> Result<()> {
            if let Some(msg) = msg {
                panic!("{}", msg)
            }
@@ -496,7 +495,7 @@ fn test_panic() -> Result<()> {
        .exec()
    }) {
        Ok(r) => panic!("no panic was detected: {:?}", r),
-        Err(p) => assert!(*p.downcast::<StdString>().unwrap() == "rust panic from lua"),
+        Err(p) => assert!(*p.downcast::<String>().unwrap() == "rust panic from lua"),
    }

    // Test disabling `catch_rust_panics` option / xpcall correctness
@@ -520,7 +519,7 @@ fn test_panic() -> Result<()> {
        .exec()
    }) {
        Ok(r) => panic!("no panic was detected: {:?}", r),
-        Err(p) => assert!(*p.downcast::<StdString>().unwrap() == "rust panic from lua"),
+        Err(p) => assert!(*p.downcast::<String>().unwrap() == "rust panic from lua"),
    }

    Ok(())
@@ -684,10 +683,12 @@ fn test_pcall_xpcall() -> Result<()> {
    ))]
    assert_eq!(globals.get::<std::string::String>("xpcall_error")?, "testerror");
    #[cfg(feature = "lua51")]
-    assert!(globals
-        .get::<String>("xpcall_error")?
-        .to_str()?
-        .ends_with(": testerror"));
+    assert!(
+        globals
+            .get::<mlua::LuaString>("xpcall_error")?
+            .to_str()?
+            .ends_with(": testerror")
+    );

    // Make sure that weird xpcall error recursion at least doesn't cause unsafety or panics.
    lua.load(
@@ -1070,10 +1071,11 @@ fn test_ref_stack_exhaustion() {
        Ok(())
    })) {
        Ok(_) => panic!("no panic was detected"),
-        Err(p) => assert!(p
-            .downcast::<StdString>()
-            .unwrap()
-            .starts_with("cannot create a Lua reference, out of auxiliary stack space")),
+        Err(p) => assert!(
+            p.downcast::<String>()
+                .unwrap()
+                .starts_with("cannot create a Lua reference, out of auxiliary stack space")
+        ),
    }
 }

@@ -1218,7 +1220,11 @@ fn test_context_thread_51() -> Result<()> {
 fn test_jit_version() -> Result<()> {
    let lua = Lua::new();
    let jit: Table = lua.globals().get("jit")?;
-    assert!(jit.get::<String>("version")?.to_str()?.contains("LuaJIT"));
+    assert!(
+        jit.get::<mlua::LuaString>("version")?
+            .to_str()?
+            .contains("LuaJIT")
+    );
    Ok(())
 }

@@ -1318,7 +1324,7 @@ fn test_inspect_stack() -> Result<()> {
    // Not inside any function
    assert!(lua.inspect_stack(0, |_| ()).is_none());

-    let logline = lua.create_function(|lua, msg: StdString| {
+    let logline = lua.create_function(|lua, msg: String| {
        let r = lua
            .inspect_stack(1, |debug| {
                let source = debug.source().short_src;
@@ -1368,7 +1374,7 @@ fn test_inspect_stack() -> Result<()> {
        local function baz(a, b, c, ...)
            return stack_info()
        end
-        assert(baz() == 'DebugStack { num_ups: 1, num_params: 3, is_vararg: true }')
+        assert(baz() == 'DebugStack { num_upvalues: 1, num_params: 3, is_vararg: true }')
    "#,
    )
    .exec()?;
@@ -1381,7 +1387,7 @@ fn test_inspect_stack() -> Result<()> {
        local function baz(a, b, c, ...)
            return stack_info()
        end
-        assert(baz() == 'DebugStack { num_ups: 1 }')
+        assert(baz() == 'DebugStack { num_upvalues: 1 }')
    "#,
    )
    .exec()?;
@@ -1422,9 +1428,8 @@ fn test_traceback() -> Result<()> {
    assert!(traceback.contains("stack traceback:"));

    // Test traceback inside a function
-    let get_traceback = lua.create_function(|lua, (msg, level): (Option<StdString>, usize)| {
-        lua.traceback(msg.as_deref(), level)
-    })?;
+    let get_traceback = lua
+        .create_function(|lua, (msg, level): (Option<String>, usize)| lua.traceback(msg.as_deref(), level))?;
    lua.globals().set("get_traceback", get_traceback)?;

    lua.load(
@@ -1504,10 +1509,10 @@ fn test_multi_states() -> Result<()> {
 #[cfg(any(feature = "lua55", feature = "lua54"))]
 fn test_warnings() -> Result<()> {
    let lua = Lua::new();
-    lua.set_app_data::<Vec<(StdString, bool)>>(Vec::new());
+    lua.set_app_data::<Vec<(String, bool)>>(Vec::new());

    lua.set_warning_function(|lua, msg, incomplete| {
-        lua.app_data_mut::<Vec<(StdString, bool)>>()
+        lua.app_data_mut::<Vec<(String, bool)>>()
            .unwrap()
            .push((msg.to_string(), incomplete));
        Ok(())
@@ -1521,7 +1526,7 @@ fn test_warnings() -> Result<()> {
    lua.remove_warning_function();
    lua.warning("one more warning", false);

-    let messages = lua.app_data_ref::<Vec<(StdString, bool)>>().unwrap();
+    let messages = lua.app_data_ref::<Vec<(String, bool)>>().unwrap();
    assert_eq!(
        *messages,
        vec![
@@ -1,6 +1,6 @@
 use std::panic::catch_unwind;

-use mlua::{Error, Function, IntoLua, Lua, Result, Thread, ThreadStatus, Value};
+use mlua::{Error, Function, IntoLua, Lua, Result, Thread, Value};

 #[test]
 fn test_thread() -> Result<()> {
@@ -21,17 +21,17 @@ fn test_thread() -> Result<()> {
        .eval()?,
    )?;

-    assert_eq!(thread.status(), ThreadStatus::Resumable);
+    assert!(thread.is_resumable());
    assert_eq!(thread.resume::<i64>(0)?, 0);
-    assert_eq!(thread.status(), ThreadStatus::Resumable);
+    assert!(thread.is_resumable());
    assert_eq!(thread.resume::<i64>(1)?, 1);
-    assert_eq!(thread.status(), ThreadStatus::Resumable);
+    assert!(thread.is_resumable());
    assert_eq!(thread.resume::<i64>(2)?, 3);
-    assert_eq!(thread.status(), ThreadStatus::Resumable);
+    assert!(thread.is_resumable());
    assert_eq!(thread.resume::<i64>(3)?, 6);
-    assert_eq!(thread.status(), ThreadStatus::Resumable);
+    assert!(thread.is_resumable());
    assert_eq!(thread.resume::<i64>(4)?, 10);
-    assert_eq!(thread.status(), ThreadStatus::Finished);
+    assert!(thread.is_finished());

    let accumulate = lua.create_thread(
        lua.load(
@@ -50,9 +50,9 @@ fn test_thread() -> Result<()> {
        accumulate.resume::<()>(i)?;
    }
    assert_eq!(accumulate.resume::<i64>(4)?, 10);
-    assert_eq!(accumulate.status(), ThreadStatus::Resumable);
+    assert!(accumulate.is_resumable());
    assert!(accumulate.resume::<()>("error").is_err());
-    assert_eq!(accumulate.status(), ThreadStatus::Error);
+    assert!(accumulate.is_error());

    let thread = lua
        .load(
@@ -65,7 +65,7 @@ fn test_thread() -> Result<()> {
        "#,
        )
        .eval::<Thread>()?;
-    assert_eq!(thread.status(), ThreadStatus::Resumable);
+    assert!(thread.is_resumable());
    assert_eq!(thread.resume::<i64>(())?, 42);

    let thread: Thread = lua
@@ -92,7 +92,7 @@ fn test_thread() -> Result<()> {

    // Already running thread must be unresumable
    let thread = lua.create_thread(lua.create_function(|lua, ()| {
-        assert_eq!(lua.current_thread().status(), ThreadStatus::Running);
+        assert!(lua.current_thread().is_running());
        let result = lua.current_thread().resume::<()>(());
        assert!(
            matches!(result, Err(Error::CoroutineUnresumable)),
@@ -123,12 +123,12 @@ fn test_thread_reset() -> Result<()> {
    assert!(thread.reset(func.clone()).is_ok());

    for _ in 0..2 {
-        assert_eq!(thread.status(), ThreadStatus::Resumable);
+        assert!(thread.is_resumable());
        let _ = thread.resume::<AnyUserData>(MyUserData(arc.clone()))?;
-        assert_eq!(thread.status(), ThreadStatus::Resumable);
+        assert!(thread.is_resumable());
        assert_eq!(Arc::strong_count(&arc), 2);
        thread.resume::<()>(())?;
-        assert_eq!(thread.status(), ThreadStatus::Finished);
+        assert!(thread.is_finished());
        thread.reset(func.clone())?;
        lua.gc_collect()?;
        assert_eq!(Arc::strong_count(&arc), 1);
@@ -138,21 +138,21 @@ fn test_thread_reset() -> Result<()> {
    let func: Function = lua.load(r#"function(ud) error("test error") end"#).eval()?;
    let thread = lua.create_thread(func.clone())?;
    let _ = thread.resume::<AnyUserData>(MyUserData(arc.clone()));
-    assert_eq!(thread.status(), ThreadStatus::Error);
+    assert!(thread.is_error());
    assert_eq!(Arc::strong_count(&arc), 2);
    #[cfg(any(feature = "lua55", feature = "lua54"))]
    {
        assert!(thread.reset(func.clone()).is_err());
        // Reset behavior has changed in Lua v5.4.4
        // It's became possible to force reset thread by popping error object
-        assert!(matches!(thread.status(), ThreadStatus::Finished));
+        assert!(thread.is_finished());
        assert!(thread.reset(func.clone()).is_ok());
-        assert_eq!(thread.status(), ThreadStatus::Resumable);
+        assert!(thread.is_resumable());
    }
    #[cfg(any(feature = "lua55", feature = "lua54", feature = "luau"))]
    {
        assert!(thread.reset(func.clone()).is_ok());
-        assert_eq!(thread.status(), ThreadStatus::Resumable);
+        assert!(thread.is_resumable());
    }

    // Try reset running thread
@@ -1,6 +1,6 @@
 use std::os::raw::c_void;

-use mlua::{Function, LightUserData, Lua, Number, Result, String as LuaString, Thread};
+use mlua::{Error, Function, LightUserData, Lua, LuaString, Number, Result, Thread};

 #[test]
 fn test_lightuserdata() -> Result<()> {
@@ -30,7 +30,7 @@ fn test_boolean_type_metatable() -> Result<()> {
    let lua = Lua::new();

    let mt = lua.create_table()?;
-    mt.set("__add", Function::wrap(|a, b| Ok(a || b)))?;
+    mt.set("__add", Function::wrap(|a, b| Ok::<_, mlua::Error>(a || b)))?;
    assert_eq!(lua.type_metatable::<bool>(), None);
    lua.set_type_metatable::<bool>(Some(mt.clone()));
    assert_eq!(lua.type_metatable::<bool>().unwrap(), mt);
@@ -51,7 +51,7 @@ fn test_lightuserdata_type_metatable() -> Result<()> {
    mt.set(
        "__add",
        Function::wrap(|a: LightUserData, b: LightUserData| {
-            Ok(LightUserData((a.0 as usize + b.0 as usize) as *mut c_void))
+            Ok::<_, Error>(LightUserData((a.0 as usize + b.0 as usize) as *mut c_void))
        }),
    )?;
    lua.set_type_metatable::<LightUserData>(Some(mt.clone()));
@@ -79,7 +79,10 @@ fn test_number_type_metatable() -> Result<()> {
    let lua = Lua::new();

    let mt = lua.create_table()?;
-    mt.set("__call", Function::wrap(|n1: f64, n2: f64| Ok(n1 * n2)))?;
+    mt.set(
+        "__call",
+        Function::wrap(|n1: f64, n2: f64| Ok::<_, Error>(n1 * n2)),
+    )?;
    lua.set_type_metatable::<Number>(Some(mt.clone()));
    assert_eq!(lua.type_metatable::<Number>().unwrap(), mt);

@@ -96,7 +99,7 @@ fn test_string_type_metatable() -> Result<()> {
    let mt = lua.create_table()?;
    mt.set(
        "__add",
-        Function::wrap(|a: String, b: String| Ok(format!("{a}{b}"))),
+        Function::wrap(|a: String, b: String| Ok::<_, Error>(format!("{a}{b}"))),
    )?;
    lua.set_type_metatable::<LuaString>(Some(mt.clone()));
    assert_eq!(lua.type_metatable::<LuaString>().unwrap(), mt);
@@ -113,7 +116,7 @@ fn test_function_type_metatable() -> Result<()> {
    let mt = lua.create_table()?;
    mt.set(
        "__index",
-        Function::wrap(|_: Function, key: String| Ok(format!("function.{key}"))),
+        Function::wrap(|_: Function, key: String| Ok::<_, Error>(format!("function.{key}"))),
    )?;
    lua.set_type_metatable::<Function>(Some(mt.clone()));
    assert_eq!(lua.type_metatable::<Function>(), Some(mt));
@@ -132,7 +135,7 @@ fn test_thread_type_metatable() -> Result<()> {
    let mt = lua.create_table()?;
    mt.set(
        "__index",
-        Function::wrap(|_: Thread, key: String| Ok(format!("thread.{key}"))),
+        Function::wrap(|_: Thread, key: String| Ok::<_, Error>(format!("thread.{key}"))),
    )?;
    lua.set_type_metatable::<Thread>(Some(mt.clone()));
    assert_eq!(lua.type_metatable::<Thread>(), Some(mt));
@@ -1,14 +1,13 @@
 use std::any::TypeId;
 use std::collections::HashMap;
-use std::string::String as StdString;
 use std::sync::Arc;

 #[cfg(any(feature = "lua55", feature = "lua54"))]
 use std::sync::atomic::{AtomicI64, Ordering};

 use mlua::{
-    AnyUserData, Error, ExternalError, Function, Lua, MetaMethod, Nil, ObjectLike, Result, String, UserData,
-    UserDataFields, UserDataMethods, UserDataRef, UserDataRegistry, Value, Variadic,
+    AnyUserData, Error, ExternalError, Function, Lua, LuaString, MetaMethod, Nil, ObjectLike, Result,
+    UserData, UserDataFields, UserDataMethods, UserDataOwned, UserDataRef, UserDataRegistry, Value, Variadic,
 };

 #[test]
@@ -131,7 +130,7 @@ fn test_metamethods() -> Result<()> {
                MetaMethod::Eq,
                |_, (lhs, rhs): (UserDataRef<Self>, UserDataRef<Self>)| Ok(lhs.0 == rhs.0),
            );
-            methods.add_meta_method(MetaMethod::Index, |_, data, index: String| {
+            methods.add_meta_method(MetaMethod::Index, |_, data, index: LuaString| {
                if index.to_str()? == "inner" {
                    Ok(data.0)
                } else {
@@ -291,8 +290,8 @@ fn test_gc_userdata() -> Result<()> {
    let lua = Lua::new();
    lua.globals().set("userdata", MyUserdata { id: 123 })?;

-    assert!(lua
-        .load(
+    assert!(
+        lua.load(
            r#"
            local tbl = setmetatable({
                userdata = userdata
@@ -308,7 +307,8 @@ fn test_gc_userdata() -> Result<()> {
        "#
        )
        .exec()
-        .is_err());
+        .is_err()
+    );

    Ok(())
 }
@@ -491,8 +491,8 @@ fn test_user_values() -> Result<()> {
    ud.set_nth_user_value(1, "hello")?;
    ud.set_nth_user_value(2, "world")?;
    ud.set_nth_user_value(65535, 321)?;
-    assert_eq!(ud.nth_user_value::<String>(1)?, "hello");
-    assert_eq!(ud.nth_user_value::<String>(2)?, "world");
+    assert_eq!(ud.nth_user_value::<LuaString>(1)?, "hello");
+    assert_eq!(ud.nth_user_value::<LuaString>(2)?, "world");
    assert_eq!(ud.nth_user_value::<Value>(3)?, Value::Nil);
    assert_eq!(ud.nth_user_value::<i32>(65535)?, 321);

@@ -582,8 +582,8 @@ fn test_fields() -> Result<()> {
            });

            // Use userdata "uservalue" storage
-            fields.add_field_function_get("uval", |_, ud| ud.user_value::<Option<String>>());
-            fields.add_field_function_set("uval", |_, ud, s: Option<String>| ud.set_user_value(s));
+            fields.add_field_function_get("uval", |_, ud| ud.user_value::<Option<LuaString>>());
+            fields.add_field_function_set("uval", |_, ud, s: Option<LuaString>| ud.set_user_value(s));

            fields.add_meta_field(MetaMethod::Index, HashMap::from([("f", 321)]));
            fields.add_meta_field_with(MetaMethod::NewIndex, |lua| {
@@ -630,9 +630,11 @@ fn test_fields() -> Result<()> {
        }

        fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
-            methods.add_meta_method(MetaMethod::Index, |_, _, name: StdString| match &*name {
-                "y" => Ok(Some(-1)),
-                _ => Ok(None),
+            methods.add_meta_method(MetaMethod::Index, |_, _, name: LuaString| {
+                match name.to_str()?.as_ref() {
+                    "y" => Ok(Some(-1)),
+                    _ => Ok(None),
+                }
            });
        }
    }
@@ -659,7 +661,7 @@ fn test_metatable() -> Result<()> {
        fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
            methods.add_function("my_type_name", |_, data: AnyUserData| {
                let metatable = data.metatable()?;
-                metatable.get::<String>(MetaMethod::Type)
+                metatable.get::<LuaString>(MetaMethod::Type)
            });
        }
    }
@@ -723,7 +725,47 @@ fn test_metatable() -> Result<()> {

    let ud = lua.create_userdata(MyUserData3)?;
    let metatable = ud.metatable()?;
-    assert_eq!(metatable.get::<String>(MetaMethod::Type)?.to_str()?, "CustomName");
+    assert_eq!(
+        metatable.get::<LuaString>(MetaMethod::Type)?.to_str()?,
+        "CustomName"
+    );
+
+    Ok(())
+}
+
+#[test]
+fn test_userdata_type_name() -> Result<()> {
+    struct MyUserData;
+    impl UserData for MyUserData {}
+
+    struct MyUserdataCustom;
+    impl UserData for MyUserdataCustom {
+        fn add_fields<F: UserDataFields<Self>>(fields: &mut F) {
+            fields.add_meta_field_with(MetaMethod::Type, |_| Ok("MyCustomName"));
+        }
+    }
+
+    // mlua always sets __name/__type; override with a non-string to test the "userdata" fallback
+    struct MyUserdataInvalid;
+    impl UserData for MyUserdataInvalid {
+        fn add_fields<F: UserDataFields<Self>>(fields: &mut F) {
+            fields.add_meta_field_with(MetaMethod::Type, |_| Ok(42_i64));
+        }
+    }
+
+    let lua = Lua::new();
+
+    // Default is the Rust type name
+    let ud = lua.create_userdata(MyUserData)?;
+    assert_eq!(ud.type_name()?, "MyUserData");
+
+    // Custom name from metatable
+    let ud = lua.create_userdata(MyUserdataCustom)?;
+    assert_eq!(ud.type_name()?, "MyCustomName");
+
+    // Invalid type name should fallback to "userdata"
+    let ud = lua.create_userdata(MyUserdataInvalid)?;
+    assert_eq!(ud.type_name()?.to_str()?, "userdata");

    Ok(())
 }
@@ -776,16 +818,16 @@ fn test_userdata_proxy() -> Result<()> {
 fn test_any_userdata() -> Result<()> {
    let lua = Lua::new();

-    lua.register_userdata_type::<StdString>(|reg| {
+    lua.register_userdata_type::<String>(|reg| {
        reg.add_method("get", |_, this, ()| Ok(this.clone()));
-        reg.add_method_mut("concat", |_, this, s: String| {
+        reg.add_method_mut("concat", |_, this, s: LuaString| {
            this.push_str(&s.to_string_lossy());
            Ok(())
        });
    })?;

    let ud = lua.create_any_userdata("hello".to_string())?;
-    assert_eq!(&*ud.borrow::<StdString>()?, "hello");
+    assert_eq!(&*ud.borrow::<String>()?, "hello");

    lua.globals().set("ud", ud)?;
    lua.load(
@@ -805,7 +847,7 @@ fn test_any_userdata() -> Result<()> {
 fn test_any_userdata_wrap() -> Result<()> {
    let lua = Lua::new();

-    lua.register_userdata_type::<StdString>(|reg| {
+    lua.register_userdata_type::<String>(|reg| {
        reg.add_method("get", |_, this, ()| Ok(this.clone()));
    })?;

@@ -857,7 +899,7 @@ fn test_userdata_object_like() -> Result<()> {
        r => panic!("expected RuntimeError, got {r:?}"),
    }

-    assert_eq!(ud.call::<String>(())?, "called");
+    assert_eq!(ud.call::<LuaString>(())?, "called");

    ud.call_method::<()>("add", 2)?;
    assert_eq!(ud.get::<u32>("n")?, 323);
@@ -1371,11 +1413,11 @@ fn test_userdata_namecall() -> Result<()> {
    struct MyUserData;

    impl UserData for MyUserData {
-        fn register(registry: &mut mlua::UserDataRegistry<Self>) {
+        fn register(registry: &mut UserDataRegistry<Self>) {
            registry.add_method("method", |_, _, ()| Ok("method called"));
            registry.add_field_method_get("field", |_, _| Ok("field value"));

-            registry.add_meta_method(MetaMethod::Index, |_, _, key: StdString| Ok(key));
+            registry.add_meta_method(MetaMethod::Index, |_, _, key: LuaString| Ok(key));

            registry.enable_namecall();
        }
@@ -1413,7 +1455,53 @@ fn test_userdata_get_path() -> Result<()> {
    }

    let ud = lua.create_userdata(MyUd)?;
-    assert_eq!(ud.get_path::<String>(".value")?, "userdata_value");
+    assert_eq!(ud.get_path::<LuaString>(".value")?, "userdata_value");
+
+    Ok(())
+}
+
+#[test]
+fn test_userdata_owned() -> Result<()> {
+    #[derive(Debug)]
+    struct MyUserdata(Arc<i64>);
+
+    impl UserData for MyUserdata {
+        fn register(registry: &mut UserDataRegistry<Self>) {
+            registry.add_method("num", |_, this, ()| Ok(*this.0));
+        }
+    }
+
+    let lua = Lua::new();
+    let rc = Arc::new(42);
+
+    // It takes ownership and destructs the Lua userdata
+    let ud = lua.create_userdata(MyUserdata(rc.clone()))?;
+    assert_eq!(Arc::strong_count(&rc), 2);
+    let owned: UserDataOwned<MyUserdata> = lua.convert(&ud)?;
+    assert_eq!(*owned.0.0, 42);
+    drop(owned);
+    assert_eq!(Arc::strong_count(&rc), 1);
+    match ud.borrow::<MyUserdata>() {
+        Err(Error::UserDataDestructed) => {}
+        r => panic!("expected UserDataDestructed, got {:?}", r),
+    }
+
+    // Cannot take while borrowed
+    let rc = Arc::new(7);
+    let ud = lua.create_userdata(MyUserdata(rc.clone()))?;
+    let borrowed = ud.borrow::<MyUserdata>()?;
+    match lua.convert::<UserDataOwned<MyUserdata>>(&ud) {
+        Err(Error::UserDataBorrowMutError) => {}
+        r => panic!("expected UserDataBorrowMutError, got {:?}", r),
+    }
+    drop(borrowed);
+
+    // Works as a function parameter
+    let f = lua.create_function(|_, owned: UserDataOwned<MyUserdata>| Ok(*owned.0.0))?;
+    let rc = Arc::new(55);
+    let ud = lua.create_userdata(MyUserdata(rc.clone()))?;
+    assert_eq!(f.call::<i64>(ud)?, 55);
+    assert_eq!(Arc::strong_count(&rc), 1); // dropped after call

    Ok(())
 }
@@ -1,9 +1,11 @@
 use std::collections::HashMap;
 use std::os::raw::c_void;
 use std::ptr;
-use std::string::String as StdString;

-use mlua::{Error, LightUserData, Lua, MultiValue, Result, UserData, UserDataMethods, Value};
+use mlua::{
+    AnyUserData, Error, LightUserData, Lua, MultiValue, Result, UserData, UserDataMethods, UserDataRegistry,
+    Value,
+};

 #[test]
 fn test_value_eq() -> Result<()> {
@@ -178,7 +180,7 @@ fn test_value_to_string() -> Result<()> {
    assert!(thread.to_string()?.starts_with("thread:"));
    assert_eq!(thread.type_name(), "thread");

-    lua.register_userdata_type::<StdString>(|reg| {
+    lua.register_userdata_type::<String>(|reg| {
        reg.add_meta_method("__tostring", |_, this, ()| Ok(this.clone()));
    })?;
    let ud: Value = Value::UserData(lua.create_any_userdata(String::from("string userdata"))?);
@@ -213,12 +215,37 @@ fn test_value_to_string() -> Result<()> {
 fn test_debug_format() -> Result<()> {
    let lua = Lua::new();

-    lua.register_userdata_type::<HashMap<i32, StdString>>(|_| {})?;
+    lua.register_userdata_type::<HashMap<i32, String>>(|_| {})?;
    let ud = lua
-        .create_any_userdata::<HashMap<i32, StdString>>(HashMap::new())
+        .create_any_userdata::<HashMap<i32, String>>(HashMap::new())
        .map(Value::UserData)?;
    assert!(format!("{ud:#?}").starts_with("HashMap<i32, String>:"));

+    struct ToDebugUserData;
+    impl UserData for ToDebugUserData {
+        fn register(registry: &mut UserDataRegistry<Self>) {
+            registry.add_meta_method("__tostring", |_, _, ()| Ok("regular-string"));
+            registry.add_meta_method("__todebugstring", |_, _, ()| Ok("debug-string"));
+        }
+    }
+    let debug_ud = Value::UserData(lua.create_userdata(ToDebugUserData)?);
+    assert_eq!(debug_ud.to_string()?, "regular-string");
+    assert_eq!(format!("{debug_ud:#?}"), "debug-string");
+
+    struct ToStringUserData;
+    impl UserData for ToStringUserData {
+        fn register(registry: &mut UserDataRegistry<Self>) {
+            registry.add_meta_method("__tostring", |_, _, ()| Ok("regular-string"));
+        }
+    }
+    let tostring_only_ud = Value::UserData(lua.create_userdata(ToStringUserData)?);
+    assert_eq!(format!("{tostring_only_ud:#?}"), "regular-string");
+
+    // Check that `AnyUsedata` pretty debug format is same as for `Value::UserData`
+    let any_ud: AnyUserData = lua.create_userdata(ToDebugUserData)?;
+    let value_ud = Value::UserData(any_ud.clone());
+    assert_eq!(format!("{any_ud:#?}"), format!("{value_ud:#?}"));
+
    Ok(())
 }

@@ -259,9 +286,11 @@ fn test_value_conversions() -> Result<()> {
    assert!(Value::Table(lua.create_table()?).is_table());
    assert!(Value::Table(lua.create_table()?).as_table().is_some());
    assert!(Value::Function(lua.create_function(|_, ()| Ok(())).unwrap()).is_function());
-    assert!(Value::Function(lua.create_function(|_, ()| Ok(())).unwrap())
-        .as_function()
-        .is_some());
+    assert!(
+        Value::Function(lua.create_function(|_, ()| Ok(())).unwrap())
+            .as_function()
+            .is_some()
+    );
    assert!(Value::Thread(lua.create_thread(lua.load("function() end").eval()?)?).is_thread());
    assert!(
        Value::Thread(lua.create_thread(lua.load("function() end").eval()?)?)
Author	SHA1	Message	Date
Alex Orlenko	5f0e06fb66	Update CHANGELOG	2026-04-22 00:06:11 +01:00
Alex Orlenko	181c9d07b7	v0.12.0-rc.1	2026-04-20 00:24:58 +01:00
Alex Orlenko	4e827179d1	Update compile tests messages	2026-04-20 00:19:56 +01:00
Alex Orlenko	cc26dcd4ff	Bump rustyline	2026-04-20 00:16:34 +01:00
Alex Orlenko	201e30bc07	Add `UserDataOwned<T>` wrapper to take ownership of userdata `T` It implements `FromLua` and takes ownership of a Lua userdata value. The semantics is similar to `AnyUserData::take`, preventing any further use from Lua. Closes #686	2026-04-20 00:05:57 +01:00
Alex Orlenko	4e028d8409	Change `AnyUserData::type_name` to return `LuaString` instead. This avoids unnecessary allocation and returns type name as it stored in metatable.	2026-04-19 23:26:24 +01:00
Alex Orlenko	3d1ae981d3	Update docs	2026-04-19 22:12:17 +01:00
Alex Orlenko	8c93948f2f	Fix tests	2026-04-18 16:13:23 +01:00
Alex Orlenko	f2b5cc44de	`traits` module no longer need to be public The LuaNativeFn traits were moved to the `function` module and all other traits as re-exported.	2026-04-18 16:09:17 +01:00
Alex Orlenko	27f91dfd1b	Accept any error in `Function::wrap/wrap_mut/wrap_async` Previously wrapped functions were required to return `mlua::Result`. Now it's possible to wrap functions returning any errors as long as they implement `std::error::Error`. Existing code remains compatible with `mlua::Result` as this type is not converted to an external error.	2026-04-18 16:01:35 +01:00
Alex Orlenko	75ff11f795	Move LuaNativeFn/Mut into `function` module	2026-04-18 14:56:24 +01:00
Alex Orlenko	df6097ab38	Mark Luau `CompileConstant` as non_exhaustive	2026-04-18 14:51:54 +01:00
Alex Orlenko	65bb6279ee	Update serde types visibility	2026-04-18 14:47:26 +01:00
Alex Orlenko	31b88e85bb	cargo fmt	2026-04-18 13:26:42 +01:00
Alex Orlenko	3be4745190	Add initial Luau integer64 type support RFC: https://rfcs.luau.org/type-long-integer.html Unfortunately this type is not backward compatible with regular numbers and require a special "integer" library. It's not integrated with `Value` enum to keep it simple.	2026-04-18 13:14:05 +01:00
Alex Orlenko	c52deec988	Use c_int for userdata metatable id	2026-04-18 13:14:05 +01:00
三咲雅 misaki masa	3ab3c997b3	feat: support external strings for `Cow<str>` and `Cow<CStr>` (#692 )	2026-04-09 10:45:15 +01:00
Alex Orlenko	5872ed70f5	Make `traits` module public	2026-04-04 15:04:00 +01:00
Alex Orlenko	e7e92b4f6f	Make `chunk` module public	2026-04-03 13:58:05 +01:00
Alex Orlenko	d27693b61a	Make `error` module public	2026-03-29 10:26:45 +01:00
Alex Orlenko	c9848d6faf	Update doc/example for (hidden) `Lua::exec_raw_lua`	2026-03-28 23:57:35 +00:00
Alex Orlenko	9126bb8ce0	Add `RawLua::pop` method	2026-03-28 22:37:25 +00:00
Alex Orlenko	7f1d716a44	Remove deprecated `Lua::load_from_function`	2026-03-28 17:40:22 +00:00
Alex Orlenko	be56e2205c	Update GC `step_size` doc	2026-03-28 17:38:49 +00:00
Alex Orlenko	c5aadc68cd	Open `UserDataMethods::add_method_once` and `UserDataMethods::add_async_method_once`	2026-03-28 17:17:57 +00:00
Alex Orlenko	a5ae2a1fc3	Update useratom doc	2026-03-28 17:07:03 +00:00
Alex Orlenko	59872da63d	mlua-sys: Bump lua-src and luajit-src dependencies	2026-03-28 16:31:19 +00:00
Alex Orlenko	a24d2151af	Minor fixes in docs	2026-03-27 22:54:56 +00:00
Alex Orlenko	56c227fd7e	Make `state` module public	2026-03-08 00:06:18 +00:00
Alex Orlenko	d5d66abe42	Refactor GC control API - Replace `gc_inc/gc_gen` with `gc_set_mode` - Add `GcIncParams` and `GcGenParams` for GC tuning - Remove `gc_step_kbytes` (it's very rare needed and Lua 5.5 has changed the input param from kbytes to bytes)	2026-03-07 23:52:10 +00:00
Alex Orlenko	a2d8b21964	Make `luau` module public	2026-03-01 16:40:19 +00:00
Alex Orlenko	a9604c4946	Rename Luau's TextRequirer to FsRequirer	2026-03-01 16:27:41 +00:00
Alex Orlenko	81ae8e1393	Make `Chunk::wrap` public	2026-03-01 16:17:11 +00:00
Alex Orlenko	a959b98d30	Add chunk module doc and update prelude re-exports	2026-03-01 16:11:38 +00:00
Alex Orlenko	efd0856033	Derive `PartialEq` for `Thread`	2026-02-28 14:52:59 +00:00
Alex Orlenko	c91066006f	Make `thread` module public	2026-02-28 14:44:50 +00:00
Alex Orlenko	a45fe9bb93	Bump luau-src to 0.19 (Luau 0.710)	2026-02-28 12:03:37 +00:00
Alex Orlenko	f1a97e4193	Open `Thread::state()` that returns `*mut lua_State` pointer.	2026-02-28 11:48:59 +00:00
Alex Orlenko	47e6a37323	Add shortcuts to check thread status (`Thread::is_resumable()`, `Thread::is_finished()` etc)	2026-02-28 11:46:05 +00:00
Alex Orlenko	bf0c96908f	Remove lifetime from `BorrowedStr` and `BorrowedBytes` The underlying `ValueRef` is cheap to clone as only increases reference count, instead of allocating a new Lua stack slot.	2026-02-23 10:24:31 +00:00
Alex Orlenko	8817720362	Re-export (hidden) `TablePairs` and `TableSequence`	2026-02-23 09:51:24 +00:00
Alex Orlenko	35294359ad	Inline doc for some types	2026-02-22 19:58:28 +00:00
Alex Orlenko	eb76db59da	Make `userdata` module public	2026-02-22 19:52:57 +00:00
Alex Orlenko	33bf3ffde7	Fix doc warnings	2026-02-22 14:37:23 +00:00
Alex Orlenko	0f3fdb0539	Make `string` module public	2026-02-22 14:33:38 +00:00
Alex Orlenko	79d438aaad	Build CI docs on main branch	2026-02-22 13:28:48 +00:00
Alex Orlenko	30cf4bef58	Use RwLock directly instead of UserDataCell	2026-02-22 00:13:19 +00:00
Alex Orlenko	5776c72208	Use `parking_lot::RwLock` in `UserDataCell` container in "send" mode. In non-send mode, mimic the `RwLock` API (using `Cell<isize>` counter). We're continue manually operating the underlying `RawRwLock` for flexibility.	2026-02-21 23:18:39 +00:00
Alex Orlenko	943c3aed58	Some minor fixes in userdata cell	2026-02-21 21:19:42 +00:00
Alex Orlenko	8fcb6a8416	Update dependencies	2026-02-21 15:38:00 +00:00
Alex Orlenko	452dc8be88	clippy	2026-02-21 15:31:48 +00:00
Alex Orlenko	63a255bbc9	Replace `is_sync` specialization trick with `MaybeSync` trait bound. The `is_sync::<T>()` runtime check relied on implicit specialization via `Copy`/`Clone` array behavior, which has changed in Rust 1.86+. `UserDataRef` always taking an exclusive lock even for `Sync` userdata, preventing concurrent shared borrows. With the `send` feature flag enabled, userdata types must now be `Send + Sync`. This is a breaking change, `T: Send + !Sync` userdata types can be wrapped in a `Mutex` or used inside a `Scope` where this restriction is lifted.	2026-02-21 15:05:55 +00:00
Alex Orlenko	151adc0e87	Implement pretty debug format for `AnyUserData` similar to `Value::UserData`.	2026-02-20 20:31:29 +00:00
Alex Orlenko	7f3ec63ab5	Support `__todebugstring` for pretty userdata debug output Close #681	2026-02-20 18:59:53 +00:00
Alex Orlenko	f19c6aac3b	Fix tests	2026-02-12 16:20:51 +00:00
Alex Orlenko	29af448ad9	Update README to indicate dev status	2026-02-12 15:28:32 +00:00
Alex Orlenko	497d84828a	Add CI to build dev docs	2026-02-03 22:40:29 +00:00
Alex Orlenko	0e489901a5	Update `debug` module Move debug types from root to new new module.	2026-02-03 22:39:33 +00:00
Alex Orlenko	88063e756f	Make `table` module public	2026-01-30 13:18:46 +00:00
Alex Orlenko	c8436e2b80	Make `function` module public Reduce number of function-specific types exported to the mlua root and keep them inside the module.	2026-01-30 13:18:05 +00:00
Alex Orlenko	613748ec16	Use `Error::from_lua_conversion` helper	2026-01-29 23:09:52 +00:00
Alex Orlenko	2fbd266da6	Remove `Error::ToLuaConversionError` This variant used only once and not practically useful.	2026-01-29 23:04:30 +00:00
Alex Orlenko	c79b5e9cdb	cargo fmt	2026-01-29 23:03:56 +00:00
Alex Orlenko	2ace892613	Rename `string::String` to `LuaString`	2026-01-29 18:45:41 +00:00
Alex Orlenko	c1ffd4e790	Replace `get_or_insert_with` with `get_or_insert_default`	2026-01-29 10:46:58 +00:00
Alex Orlenko	d9c139b55f	Rust 2024	2026-01-29 10:33:28 +00:00
Alex Orlenko	0c4206c97d	Bump min Rust version to 1.88	2026-01-29 10:13:04 +00:00
Alex Orlenko	a985dc7a37	Start 0.12.0-dev.1	2026-01-29 10:07:05 +00:00