v0.6.1

This can happen if we unable to push metatable with `__gc` metamethod after pushing userdata.
In this case Lua will never execute drop.
Instead, we will push metatable first and then userdata.

CHANGELOG.md

@@ -1,3 +1,37 @@
+## v0.6.1
+
+- Update `chunk!` documentation (stable Rust limitations)
+- Fixed Lua sequence table conversion to HashSet/BTreeSet
+- `once_cell` dependency lowered to 1.0
+
+## v0.6.0
+Changes since 0.5.4
+- New `UserDataFields` API
+- Full access to `UserData` metatables with support of setting arbitrary fields.
+- Implement `UserData` for `Rc<RefCell<T>>`/`Arc<Mutex<T>>`/`Arc<RwLock<T>>` where `T: UserData`.
+- Added `SerializeOptions` to to change default Lua serializer behaviour (eg. `nil/null/array` serialization)
+- Added `LuaOptions` to customize Lua/Rust behaviour (currently panic handling)
+- Added `ToLua`/`FromLua` implementation for `Box<str>` and `Box<[T]>`.
+- Added `Thread::reset()` for luajit/lua54 to recycle threads (coroutines) with attaching a new function.
+- Added `chunk!` macro support to load chunks of Lua code using the Rust tokenizer and optionally capturing Rust variables.
+- Improved errors reporting (`Error`'s `__tostring` method formats full stacktraces). This is useful in a module mode.
+- Added `String::to_string_lossy`
+- Various bugfixes and improvements
+
+Breaking changes:
+- Errors are always `Send + Sync` to be compatible with the anyhow crate.
+- Removed `Result` from `LuaSerdeExt::null()` and `LuaSerdeExt::array_metatable()` (never fails)
+- Removed `Result` from `Function::dump()` (never fails)
+- Removed `AnyUserData::has_metamethod()` (in favour of full access to metatables)
+
+## v0.6.0-beta.3
+
+- Errors are always `Send + Sync` to be compatible with anyhow crate
+- Implement `UserData` for `Rc<RefCell>`/`Arc<Mutex>`/`Arc<RwLock>`
+- Added `__ipairs` metamethod for Lua 5.2
+- Added `String::to_string_lossy`
+- Various bugfixes and improvements
+
 ## v0.6.0-beta.2
 
 - [**Breaking**] Removed `AnyUserData::has_metamethod()`

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mlua"
-version = "0.6.0-beta.2" # remember to update html_root_url and mlua_derive
+version = "0.6.1" # remember to update html_root_url and mlua_derive
 authors = ["Aleksandr Orlenko <zxteam@pm.me>", "kyren <catherine@chucklefish.org>"]
 edition = "2018"
 repository = "https://github.com/khvzak/mlua"
@@ -41,9 +41,9 @@ serialize = ["serde", "erased-serde"]
 macros = ["mlua_derive/macros"]
 
 [dependencies]
-mlua_derive = { version = "=0.6.0-beta.2", optional = true, path = "mlua_derive" }
+mlua_derive = { version = "=0.6.0", optional = true, path = "mlua_derive" }
 bstr = { version = "0.2", features = ["std"], default_features = false }
-once_cell = { version = "1.7" }
+once_cell = { version = "1.0" }
 num-traits = { version = "0.2.14" }
 futures-core = { version = "0.3.5", optional = true }
 futures-task = { version = "0.3.5", optional = true }
@@ -76,11 +76,11 @@ required-features = ["async"]
 
 [[example]]
 name = "async_http_client"
-required-features = ["async"]
+required-features = ["async", "macros"]
 
 [[example]]
 name = "async_http_reqwest"
-required-features = ["async", "serialize"]
+required-features = ["async", "serialize", "macros"]
 
 [[example]]
 name = "async_http_server"
@@ -88,8 +88,16 @@ required-features = ["async", "send"]
 
 [[example]]
 name = "async_tcp_server"
-required-features = ["async"]
+required-features = ["async", "macros"]
+
+[[example]]
+name = "guided_tour"
+required-features = ["macros"]
 
 [[example]]
 name = "serialize"
 required-features = ["serialize"]
+
+[[example]]
+name = "userdata"
+required-features = ["macros"]

README.md

@@ -38,6 +38,7 @@ Below is a list of the available feature flags. By default `mlua` does not enabl
 * `async`: enable async/await support (any executor can be used, eg. [tokio] or [async-std])
 * `send`: make `mlua::Lua` transferable across thread boundaries (adds [`Send`] requirement to `mlua::Function` and `mlua::UserData`)
 * `serialize`: add serialization and deserialization support to `mlua` types using [serde] framework
+* `macros`: enable procedural macros (such as `chunk!`)
 
 [5.4]: https://www.lua.org/manual/5.4/manual.html
 [5.3]: https://www.lua.org/manual/5.3/manual.html
@@ -96,7 +97,7 @@ Add to `Cargo.toml` :
 
 ``` toml
 [dependencies]
-mlua = { version = "0.5", features = ["lua53", "vendored"] }
+mlua = { version = "0.6", features = ["lua53", "vendored"] }
 ```
 
 `main.rs`
@@ -131,7 +132,7 @@ Add to `Cargo.toml` :
 crate-type = ["cdylib"]
 
 [dependencies]
-mlua = { version = "0.5", features = ["lua53", "vendored", "module"] }
+mlua = { version = "0.6", features = ["lua53", "vendored", "module"] }
 ```
 
 `lib.rs` :
@@ -184,6 +185,15 @@ MSVC with `LUA_INC` / `LUA_LIB` / `LUA_LIB_NAME` environment variables.
 
 More details about compiling and linking Lua modules can be found on the [Building Modules](http://lua-users.org/wiki/BuildingModules) page.
 
+### Publishing to luarocks.org
+
+There is a LuaRocks build backend for mlua modules [`luarocks-build-rust-mlua`].
+
+Modules written in Rust and published to luarocks:
+- [`lua-ryaml`](https://github.com/khvzak/lua-ryaml)
+
+[`luarocks-build-rust-mlua`]: https://luarocks.org/modules/khvzak/luarocks-build-rust-mlua
+
 ## Safety
 
 One of the `mlua` goals is to provide *safe* API between Rust and Lua.

build/main.rs

@@ -239,14 +239,5 @@ fn main() {
         println!("cargo:rerun-if-changed=src/ffi/glue/glue.c");
     }
 
-    let mut shim_cc = cc::Build::new();
-    shim_cc
-        .include(include_dir)
-        .define("COMPAT53_INCLUDE_SOURCE", None);
-    #[cfg(feature = "luajit")]
-    shim_cc.define("COMPAT53_LUAJIT", None);
-    shim_cc.file("src/ffi/shim/shim.c").compile("shim");
-
-    println!("cargo:rerun-if-changed=src/ffi/shim");
     println!("cargo:rerun-if-changed=build");
 }

examples/async_http_client.rs

@@ -1,12 +1,11 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 
-use bstr::BString;
 use hyper::body::{Body as HyperBody, HttpBody as _};
 use hyper::Client as HyperClient;
 use tokio::sync::Mutex;
 
-use mlua::{Error, Lua, Result, UserData, UserDataMethods};
+use mlua::{chunk, ExternalResult, Lua, Result, UserData, UserDataMethods};
 
 #[derive(Clone)]
 struct BodyReader(Arc<Mutex<HyperBody>>);
@@ -19,11 +18,11 @@ impl BodyReader {
 
 impl UserData for BodyReader {
     fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
-        methods.add_async_method("read", |_, reader, ()| async move {
+        methods.add_async_method("read", |lua, reader, ()| async move {
             let mut reader = reader.0.lock().await;
             if let Some(bytes) = reader.data().await {
-                let bytes = bytes.map_err(Error::external)?;
-                return Ok(Some(BString::from(bytes.as_ref())));
+                let bytes = bytes.to_lua_err()?;
+                return Some(lua.create_string(&bytes)).transpose();
             }
             Ok(None)
         });
@@ -36,18 +35,18 @@ async fn main() -> Result<()> {
 
     let fetch_url = lua.create_async_function(|lua, uri: String| async move {
         let client = HyperClient::new();
-        let uri = uri.parse().map_err(Error::external)?;
-        let resp = client.get(uri).await.map_err(Error::external)?;
+        let uri = uri.parse().to_lua_err()?;
+        let resp = client.get(uri).await.to_lua_err()?;
 
         let lua_resp = lua.create_table()?;
         lua_resp.set("status", resp.status().as_u16())?;
 
         let mut headers = HashMap::new();
-        for (key, value) in resp.headers().iter() {
+        for (key, value) in resp.headers() {
             headers
                 .entry(key.as_str())
                 .or_insert(Vec::new())
-                .push(value.to_str().unwrap());
+                .push(value.to_str().to_lua_err()?);
         }
 
         lua_resp.set("headers", headers)?;
@@ -56,13 +55,9 @@ async fn main() -> Result<()> {
         Ok(lua_resp)
     })?;
 
-    let globals = lua.globals();
-    globals.set("fetch_url", fetch_url)?;
-
     let f = lua
-        .load(
-            r#"
-            local res = fetch_url(...)
+        .load(chunk! {
+            local res = $fetch_url(...)
             print(res.status)
             for key, vals in pairs(res.headers) do
                 for _, val in ipairs(vals) do
@@ -75,8 +70,7 @@ async fn main() -> Result<()> {
                     print(body)
                 end
             until not body
-        "#,
-        )
+        })
         .into_function()?;
 
     f.call_async("http://httpbin.org/ip").await

examples/async_http_reqwest.rs

@@ -1,40 +1,34 @@
-use mlua::{Error, Lua, LuaSerdeExt, Result};
+use mlua::{chunk, ExternalResult, Lua, LuaSerdeExt, Result};
 
 #[tokio::main]
 async fn main() -> Result<()> {
     let lua = Lua::new();
-    let globals = lua.globals();
-    globals.set("null", lua.null())?;
+
+    let null = lua.null();
 
     let fetch_json = lua.create_async_function(|lua, uri: String| async move {
         let resp = reqwest::get(&uri)
             .await
             .and_then(|resp| resp.error_for_status())
-            .map_err(Error::external)?;
-        let json = resp
-            .json::<serde_json::Value>()
-            .await
-            .map_err(Error::external)?;
+            .to_lua_err()?;
+        let json = resp.json::<serde_json::Value>().await.to_lua_err()?;
         lua.to_value(&json)
     })?;
-    globals.set("fetch_json", fetch_json)?;
 
     let f = lua
-        .load(
-            r#"
+        .load(chunk! {
             function print_r(t, indent)
-                local indent = indent or ''
+                local indent = indent or ""
                 for k, v in pairs(t) do
                     io.write(indent, tostring(k))
-                    if type(v) == "table" then io.write(':\n') print_r(v, indent..'  ')
-                    else io.write(': ', v == null and "null" or tostring(v), '\n') end
+                    if type(v) == "table" then io.write(":\n") print_r(v, indent.."  ")
+                    else io.write(": ", v == $null and "null" or tostring(v), "\n") end
                 end
             end
 
-            local res = fetch_json(...)
+            local res = $fetch_json(...)
             print_r(res)
-        "#,
-        )
+        })
         .into_function()?;
 
     f.call_async("https://httpbin.org/anything?arg0=val0").await

examples/async_http_server.rs

@@ -1,5 +1,4 @@
 use std::net::SocketAddr;
-use std::sync::Arc;
 
 use hyper::server::conn::AddrStream;
 use hyper::service::{make_service_fn, service_fn};
@@ -7,13 +6,12 @@ use hyper::{Body, Request, Response, Server};
 
 use mlua::{Error, Function, Lua, Result, Table, UserData, UserDataMethods};
 
-#[derive(Clone)]
-struct LuaRequest(Arc<(SocketAddr, Request<Body>)>);
+struct LuaRequest(SocketAddr, Request<Body>);
 
 impl UserData for LuaRequest {
     fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
-        methods.add_method("remote_addr", |_lua, req, ()| Ok((req.0).0.to_string()));
-        methods.add_method("method", |_lua, req, ()| Ok((req.0).1.method().to_string()));
+        methods.add_method("remote_addr", |_lua, req, ()| Ok((req.0).to_string()));
+        methods.add_method("method", |_lua, req, ()| Ok((req.1).method().to_string()));
     }
 }
 
@@ -25,7 +23,7 @@ async fn run_server(handler: Function<'static>) -> Result<()> {
             Ok::<_, Error>(service_fn(move |req: Request<Body>| {
                 let handler = handler.clone();
                 async move {
-                    let lua_req = LuaRequest(Arc::new((remote_addr, req)));
+                    let lua_req = LuaRequest(remote_addr, req);
                     let lua_resp: Table = handler.call_async(lua_req).await?;
                     let body = lua_resp
                         .get::<_, Option<String>>("body")?
@@ -72,7 +70,7 @@ async fn main() -> Result<()> {
                     ["X-Req-Method"] = req:method(),
                     ["X-Remote-Addr"] = req:remote_addr(),
                 },
-                body = "Hello, World!"
+                body = "Hello, World!\n"
             }
         end
     "#,

examples/async_tcp_server.rs

@@ -1,14 +1,12 @@
 use std::sync::Arc;
 
-use bstr::BString;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};
 use tokio::sync::Mutex;
 use tokio::task;
 
-use mlua::{Function, Lua, Result, UserData, UserDataMethods};
+use mlua::{chunk, Function, Lua, Result, String as LuaString, UserData, UserDataMethods};
 
-#[derive(Clone)]
 struct LuaTcp;
 
 #[derive(Clone)]
@@ -41,15 +39,15 @@ impl UserData for LuaTcpStream {
             Ok(stream.0.lock().await.peer_addr()?.to_string())
         });
 
-        methods.add_async_method("read", |_, stream, size: usize| async move {
+        methods.add_async_method("read", |lua, stream, size: usize| async move {
             let mut buf = vec![0; size];
             let n = stream.0.lock().await.read(&mut buf).await?;
             buf.truncate(n);
-            Ok(BString::from(buf))
+            lua.create_string(&buf)
         });
 
-        methods.add_async_method("write", |_, stream, data: BString| async move {
-            let n = stream.0.lock().await.write(&data).await?;
+        methods.add_async_method("write", |_, stream, data: LuaString| async move {
+            let n = stream.0.lock().await.write(&data.as_bytes()).await?;
             Ok(n)
         });
 
@@ -66,15 +64,12 @@ async fn run_server(lua: &'static Lua) -> Result<()> {
         Ok(())
     })?;
 
-    let globals = lua.globals();
-    globals.set("tcp", LuaTcp)?;
-    globals.set("spawn", spawn)?;
+    let tcp = LuaTcp;
 
     let server = lua
-        .load(
-            r#"
+        .load(chunk! {
             local addr = ...
-            local listener = tcp.bind(addr)
+            local listener = $tcp.bind(addr)
             print("listening on "..addr)
 
             local accept_new = true
@@ -87,7 +82,7 @@ async fn run_server(lua: &'static Lua) -> Result<()> {
                     return
                 end
 
-                spawn(function()
+                $spawn(function()
                     while true do
                         local data = stream:read(100)
                         data = data:match("^%s*(.-)%s*$") -- trim
@@ -106,8 +101,7 @@ async fn run_server(lua: &'static Lua) -> Result<()> {
                     end
                 end)
             end
-        "#,
-        )
+        })
         .into_function()?;
 
     task::LocalSet::new()

examples/guided_tour.rs

@@ -1,15 +1,15 @@
 use std::f32;
 use std::iter::FromIterator;
 
-use mlua::{Function, Lua, MetaMethod, Result, UserData, UserDataMethods, Variadic};
+use mlua::{chunk, Function, Lua, MetaMethod, Result, UserData, UserDataMethods, Variadic};
 
 fn main() -> Result<()> {
-    // You can create a new Lua state with `Lua::new()`.  This loads the default Lua std library
+    // You can create a new Lua state with `Lua::new()`. This loads the default Lua std library
     // *without* the debug library.
     let lua = Lua::new();
 
-    // You can get and set global variables.  Notice that the globals table here is a permanent
-    // reference to _G, and it is mutated behind the scenes as Lua code is loaded.  This API is
+    // You can get and set global variables. Notice that the globals table here is a permanent
+    // reference to _G, and it is mutated behind the scenes as Lua code is loaded. This API is
     // based heavily around sharing and internal mutation (just like Lua itself).
 
     let globals = lua.globals();
@@ -20,8 +20,8 @@ fn main() -> Result<()> {
     assert_eq!(globals.get::<_, String>("string_var")?, "hello");
     assert_eq!(globals.get::<_, i64>("int_var")?, 42);
 
-    // You can load and evaluate Lua code.  The returned type of `Lua::load` is a builder
-    // that allows you to change settings before running Lua code.  Here, we are using it to set
+    // You can load and evaluate Lua code. The returned type of `Lua::load` is a builder
+    // that allows you to change settings before running Lua code. Here, we are using it to set
     // the name of the laoded chunk to "example code", which will be used when Lua error
     // messages are printed.
 
@@ -38,6 +38,17 @@ fn main() -> Result<()> {
     assert_eq!(lua.load("false == false").eval::<bool>()?, true);
     assert_eq!(lua.load("return 1 + 2").eval::<i32>()?, 3);
 
+    // Use can use special `chunk!` macro to use Rust tokenizer and automatically capture variables
+
+    let a = 1;
+    let b = 2;
+    let name = "world";
+    lua.load(chunk! {
+        print($a + $b)
+        print("hello, " .. $name)
+    })
+    .exec()?;
+
     // You can create and manage Lua tables
 
     let array_table = lua.create_table()?;
@@ -76,7 +87,7 @@ fn main() -> Result<()> {
     let print: Function = globals.get("print")?;
     print.call::<_, ()>("hello from rust")?;
 
-    // This API generally handles variadics using tuples.  This is one way to call a function with
+    // This API generally handles variadics using tuples. This is one way to call a function with
     // multiple parameters:
 
     print.call::<_, ()>(("hello", "again", "from", "rust"))?;
@@ -87,15 +98,15 @@ fn main() -> Result<()> {
         ["hello", "yet", "again", "from", "rust"].iter().cloned(),
     ))?;
 
-    // You can bind rust functions to Lua as well.  Callbacks receive the Lua state inself as their
-    // first parameter, and the arguments given to the function as the second parameter.  The type
+    // You can bind rust functions to Lua as well. Callbacks receive the Lua state inself as their
+    // first parameter, and the arguments given to the function as the second parameter. The type
     // of the arguments can be anything that is convertible from the parameters given by Lua, in
     // this case, the function expects two string sequences.
 
     let check_equal = lua.create_function(|_, (list1, list2): (Vec<String>, Vec<String>)| {
         // This function just checks whether two string lists are equal, and in an inefficient way.
         // Lua callbacks return `mlua::Result`, an Ok value is a normal return, and an Err return
-        // turns into a Lua 'error'.  Again, any type that is convertible to Lua may be returned.
+        // turns into a Lua 'error'. Again, any type that is convertible to Lua may be returned.
         Ok(list1 == list2)
     })?;
     globals.set("check_equal", check_equal)?;
@@ -174,7 +185,7 @@ fn main() -> Result<()> {
 
         lua.scope(|scope| {
             // We create a 'sketchy' Lua callback that holds a mutable reference to the variable
-            // `rust_val`.  Outside of a `Lua::scope` call, this would not be allowed
+            // `rust_val`. Outside of a `Lua::scope` call, this would not be allowed
             // because it could be unsafe.
 
             lua.globals().set(
@@ -191,9 +202,9 @@ fn main() -> Result<()> {
         assert_eq!(rust_val, 42);
     }
 
-    // We were able to run our 'sketchy' function inside the scope just fine.  However, if we
+    // We were able to run our 'sketchy' function inside the scope just fine. However, if we
     // try to run our 'sketchy' function outside of the scope, the function we created will have
-    // been invalidated and we will generate an error.  If our function wasn't invalidated, we
+    // been invalidated and we will generate an error. If our function wasn't invalidated, we
     // might be able to improperly access the freed `rust_val` which would be unsafe.
     assert!(lua.load("sketchy()").exec().is_err());
 

examples/module/src/lib.rs

@@ -8,10 +8,32 @@ fn used_memory(lua: &Lua, _: ()) -> LuaResult<usize> {
     Ok(lua.used_memory())
 }
 
+fn check_userdata(_: &Lua, ud: MyUserData) -> LuaResult<i32> {
+    Ok(ud.0)
+}
+
 #[mlua::lua_module]
 fn rust_module(lua: &Lua) -> LuaResult<LuaTable> {
     let exports = lua.create_table()?;
     exports.set("sum", lua.create_function(sum)?)?;
     exports.set("used_memory", lua.create_function(used_memory)?)?;
+    exports.set("check_userdata", lua.create_function(check_userdata)?)?;
     Ok(exports)
 }
+
+#[derive(Clone, Copy)]
+struct MyUserData(i32);
+
+impl LuaUserData for MyUserData {}
+
+#[mlua::lua_module]
+fn rust_module_second(lua: &Lua) -> LuaResult<LuaTable> {
+    let exports = lua.create_table()?;
+    exports.set("userdata", lua.create_userdata(MyUserData(123))?)?;
+    Ok(exports)
+}
+
+#[mlua::lua_module]
+fn rust_module_error(_: &Lua) -> LuaResult<LuaTable> {
+    Err("custom module error".to_lua_err())
+}

examples/userdata.rs

@@ -0,0 +1,45 @@
+use mlua::{chunk, Lua, MetaMethod, Result, UserData};
+
+#[derive(Default)]
+struct Rectangle {
+    length: u32,
+    width: u32,
+}
+
+impl UserData for Rectangle {
+    fn add_fields<'lua, F: mlua::UserDataFields<'lua, Self>>(fields: &mut F) {
+        fields.add_field_method_get("length", |_, this| Ok(this.length));
+        fields.add_field_method_set("length", |_, this, val| {
+            this.length = val;
+            Ok(())
+        });
+        fields.add_field_method_get("width", |_, this| Ok(this.width));
+        fields.add_field_method_set("width", |_, this, val| {
+            this.width = val;
+            Ok(())
+        });
+    }
+
+    fn add_methods<'lua, M: mlua::UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_method("area", |_, this, ()| Ok(this.length * this.width));
+        methods.add_method("diagonal", |_, this, ()| {
+            Ok((this.length.pow(2) as f64 + this.width.pow(2) as f64).sqrt())
+        });
+
+        // Constructor
+        methods.add_meta_function(MetaMethod::Call, |_, ()| Ok(Rectangle::default()));
+    }
+}
+
+fn main() -> Result<()> {
+    let lua = Lua::new();
+    let rectangle = Rectangle::default();
+    lua.load(chunk! {
+        local rect = $rectangle()
+        rect.width = 10
+        rect.length = 5
+        assert(rect:area() == 50)
+        assert(rect:diagonal() - 11.1803 < 0.0001)
+    })
+    .exec()
+}

mlua_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mlua_derive"
-version = "0.6.0-beta.2"
+version = "0.6.0"
 authors = ["Aleksandr Orlenko <zxteam@pm.me>"]
 edition = "2018"
 description = "Procedural macros for the mlua crate."

mlua_derive/src/lib.rs

@@ -1,39 +1,38 @@
 use proc_macro::TokenStream;
 use proc_macro2::{Ident, Span};
-use quote::quote_spanned;
-use syn::{parse_macro_input, spanned::Spanned, AttributeArgs, Error, ItemFn};
+use quote::quote;
+use syn::{parse_macro_input, AttributeArgs, Error, ItemFn};
 
 #[cfg(feature = "macros")]
 use {
     crate::chunk::Chunk, proc_macro::TokenTree, proc_macro2::TokenStream as TokenStream2,
-    proc_macro_error::proc_macro_error, quote::quote,
+    proc_macro_error::proc_macro_error,
 };
 
 #[proc_macro_attribute]
 pub fn lua_module(attr: TokenStream, item: TokenStream) -> TokenStream {
     let args = parse_macro_input!(attr as AttributeArgs);
-    let item = parse_macro_input!(item as ItemFn);
+    let func = parse_macro_input!(item as ItemFn);
 
     if !args.is_empty() {
-        let err = Error::new(Span::call_site(), "the number of arguments must be zero")
+        let err = Error::new(Span::call_site(), "the macro does not support arguments")
             .to_compile_error();
         return err.into();
     }
 
-    let span = item.span();
-    let item_name = item.sig.ident.clone();
-    let ext_entrypoint_name = Ident::new(&format!("luaopen_{}", item.sig.ident), Span::call_site());
+    let func_name = func.sig.ident.clone();
+    let ext_entrypoint_name = Ident::new(&format!("luaopen_{}", func_name), Span::call_site());
 
-    let wrapped = quote_spanned! { span =>
-        mlua::require_module_feature!();
+    let wrapped = quote! {
+        ::mlua::require_module_feature!();
+
+        #func
 
         #[no_mangle]
-        unsafe extern "C" fn #ext_entrypoint_name(state: *mut mlua::lua_State) -> std::os::raw::c_int {
-            #item
-
-            mlua::Lua::init_from_ptr(state)
-                .entrypoint1(#item_name)
-                .unwrap()
+        unsafe extern "C" fn #ext_entrypoint_name(state: *mut ::mlua::lua_State) -> ::std::os::raw::c_int {
+            ::mlua::Lua::init_from_ptr(state)
+                .entrypoint1(#func_name)
+                .expect("cannot initialize module")
         }
     };
 
@@ -78,15 +77,15 @@ pub fn chunk(input: TokenStream) -> TokenStream {
                 (#source).as_bytes()
             }
 
-            fn env(&self, lua: &'lua Lua) -> Option<Result<Value<'lua>>> {
+            fn env(&self, lua: &'lua Lua) -> Result<Option<Value<'lua>>> {
                 if #caps_len > 0 {
                     if let Ok(mut make_env) = self.0.lock() {
                         if let Some(make_env) = make_env.take() {
-                            return Some(make_env(lua));
+                            return make_env(lua).map(Some);
                         }
                     }
                 }
-                None
+                Ok(None)
             }
 
             fn mode(&self) -> Option<ChunkMode> {

src/conversion.rs

@@ -554,17 +554,17 @@ impl<'lua, T: Eq + Hash + ToLua<'lua>, S: BuildHasher> ToLua<'lua> for HashSet<T
 
 impl<'lua, T: Eq + Hash + FromLua<'lua>, S: BuildHasher + Default> FromLua<'lua> for HashSet<T, S> {
     fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Self> {
-        if let Value::Table(table) = value {
-            table
+        match value {
+            Value::Table(table) if table.len()? > 0 => table.sequence_values().collect(),
+            Value::Table(table) => table
                 .pairs::<T, Value<'lua>>()
                 .map(|res| res.map(|(k, _)| k))
-                .collect()
-        } else {
-            Err(Error::FromLuaConversionError {
+                .collect(),
+            _ => Err(Error::FromLuaConversionError {
                 from: value.type_name(),
                 to: "HashSet",
                 message: Some("expected table".to_string()),
-            })
+            }),
         }
     }
 }
@@ -579,17 +579,17 @@ impl<'lua, T: Ord + ToLua<'lua>> ToLua<'lua> for BTreeSet<T> {
 
 impl<'lua, T: Ord + FromLua<'lua>> FromLua<'lua> for BTreeSet<T> {
     fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Self> {
-        if let Value::Table(table) = value {
-            table
+        match value {
+            Value::Table(table) if table.len()? > 0 => table.sequence_values().collect(),
+            Value::Table(table) => table
                 .pairs::<T, Value<'lua>>()
                 .map(|res| res.map(|(k, _)| k))
-                .collect()
-        } else {
-            Err(Error::FromLuaConversionError {
+                .collect(),
+            _ => Err(Error::FromLuaConversionError {
                 from: value.type_name(),
                 to: "BTreeSet",
                 message: Some("expected table".to_string()),
-            })
+            }),
         }
     }
 }

src/error.rs

@@ -174,15 +174,13 @@ pub enum Error {
     /// Returning `Err(ExternalError(...))` from a Rust callback will raise the error as a Lua
     /// error. The Rust code that originally invoked the Lua code then receives a `CallbackError`,
     /// from which the original error (and a stack traceback) can be recovered.
-    #[cfg(feature = "send")]
     ExternalError(Arc<dyn StdError + Send + Sync>),
-    #[cfg(not(feature = "send"))]
-    ExternalError(Arc<dyn StdError>),
 }
 
 /// A specialized `Result` type used by `mlua`'s API.
 pub type Result<T> = StdResult<T, Error>;
 
+#[cfg(not(tarpaulin_include))]
 impl fmt::Display for Error {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         match *self {
@@ -277,35 +275,21 @@ impl StdError for Error {
 }
 
 impl Error {
-    #[cfg(feature = "send")]
     pub fn external<T: Into<Box<dyn StdError + Send + Sync>>>(err: T) -> Error {
         Error::ExternalError(err.into().into())
     }
-
-    #[cfg(not(feature = "send"))]
-    pub fn external<T: Into<Box<dyn StdError>>>(err: T) -> Error {
-        Error::ExternalError(err.into().into())
-    }
 }
 
 pub trait ExternalError {
     fn to_lua_err(self) -> Error;
 }
 
-#[cfg(feature = "send")]
 impl<E: Into<Box<dyn StdError + Send + Sync>>> ExternalError for E {
     fn to_lua_err(self) -> Error {
         Error::external(self)
     }
 }
 
-#[cfg(not(feature = "send"))]
-impl<E: Into<Box<dyn StdError>>> ExternalError for E {
-    fn to_lua_err(self) -> Error {
-        Error::external(self)
-    }
-}
-
 pub trait ExternalResult<T> {
     fn to_lua_err(self) -> Result<T>;
 }

src/ffi/lua.rs

@@ -111,6 +111,10 @@ pub const LUA_RIDX_GLOBALS: lua_Integer = 2;
 #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
 pub const LUA_RIDX_LAST: lua_Integer = LUA_RIDX_GLOBALS;
 
+// I believe `luaL_traceback` < 5.4 requires this much free stack to not error.
+// 5.4 uses `luaL_Buffer`
+pub const LUA_TRACEBACK_STACK: c_int = 11;
+
 /// A Lua number, usually equivalent to `f64`.
 pub type lua_Number = luaconf::LUA_NUMBER;
 

src/ffi/mod.rs

@@ -215,7 +215,8 @@ pub use self::lua::{
     LUA_MASKLINE, LUA_MASKRET, LUA_MINSTACK, LUA_MULTRET, LUA_OK, LUA_OPADD, LUA_OPDIV, LUA_OPEQ,
     LUA_OPLE, LUA_OPLT, LUA_OPMOD, LUA_OPMUL, LUA_OPPOW, LUA_OPSUB, LUA_OPUNM, LUA_REGISTRYINDEX,
     LUA_SIGNATURE, LUA_TBOOLEAN, LUA_TFUNCTION, LUA_TLIGHTUSERDATA, LUA_TNIL, LUA_TNONE,
-    LUA_TNUMBER, LUA_TSTRING, LUA_TTABLE, LUA_TTHREAD, LUA_TUSERDATA, LUA_YIELD,
+    LUA_TNUMBER, LUA_TRACEBACK_STACK, LUA_TSTRING, LUA_TTABLE, LUA_TTHREAD, LUA_TUSERDATA,
+    LUA_YIELD,
 };
 
 #[cfg(any(feature = "lua54", feature = "lua53"))]
@@ -280,6 +281,25 @@ pub const SYS_MIN_ALIGN: usize = 8;
 )))]
 pub const SYS_MIN_ALIGN: usize = 16;
 
+// Hack to avoid stripping a few unused Lua symbols that could be imported
+// by C modules in unsafe mode
+pub(crate) fn keep_lua_symbols() {
+    let mut symbols: Vec<*const extern "C" fn()> = Vec::new();
+    symbols.push(lua_atpanic as _);
+    symbols.push(lua_isuserdata as _);
+    symbols.push(lua_tocfunction as _);
+    symbols.push(luaL_loadstring as _);
+    symbols.push(luaL_openlibs as _);
+    if cfg!(any(any(
+        feature = "lua54",
+        feature = "lua53",
+        feature = "lua52"
+    ))) {
+        symbols.push(lua_getglobal as _);
+        symbols.push(lua_setglobal as _);
+    }
+}
+
 #[allow(unused_imports, dead_code, non_camel_case_types)]
 #[allow(clippy::unreadable_literal)]
 mod glue {
@@ -293,5 +313,3 @@ mod lauxlib;
 mod lua;
 mod luaconf;
 mod lualib;
-
-pub mod safe;

src/ffi/safe.rs

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

src/ffi/shim/compat-5.3.c

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

src/ffi/shim/compat-5.3.h

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

src/ffi/shim/shim.c

@@ -1,515 +0,0 @@
-// The MIT License (MIT)
-//
-// Copyright (c) 2019-2021 A. Orlenko
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-
-#include <lauxlib.h>
-#include <lua.h>
-
-#include "compat-5.3.h"
-
-size_t MLUA_WRAPPED_ERROR_SIZE = 0;
-size_t MLUA_WRAPPED_PANIC_SIZE = 0;
-
-const void *MLUA_WRAPPED_ERROR_KEY = NULL;
-const void *MLUA_WRAPPED_PANIC_KEY = NULL;
-
-extern void wrapped_error_traceback(lua_State *L, int error_idx,
-                                    int traceback_idx);
-
-extern int mlua_hook_proc(lua_State *L, lua_Debug *ar);
-
-#define max(a, b) (a > b ? a : b)
-
-// I believe luaL_traceback < 5.4 requires this much free stack to not error.
-// 5.4 uses luaL_Buffer
-const int LUA_TRACEBACK_STACK = 11;
-
-typedef struct {
-  const char *data;
-  size_t len;
-} StringArg;
-
-static void handle_wrapped_error(lua_State *L) {
-  if (lua_checkstack(L, LUA_TRACEBACK_STACK) != 0) {
-    luaL_traceback(L, L, NULL, 0);
-    // Convert to CallbackError and attach traceback
-    wrapped_error_traceback(L, -2, -1);
-    lua_pop(L, 1);
-  } else {
-    // Convert to CallbackError with error message as a traceback
-    wrapped_error_traceback(L, -1, 0);
-  }
-}
-
-// A wrapper around Rust function to protect from triggering longjmp in Rust.
-// Rust callback expected to return positive number of output values or
-// -1 in case of error, -2 in case of panic.
-static int lua_call_rust(lua_State *L) {
-  int nargs = lua_gettop(L);
-
-  // We need one extra stack space to store preallocated memory, and at least 2
-  // stack spaces overall for handling error metatables in rust fn
-  int extra_stack = 1;
-  if (nargs < 2) {
-    extra_stack = 2 - nargs;
-  }
-
-  luaL_checkstack(L, extra_stack,
-                  "not enough stack space for callback error handling");
-
-  // We cannot shadow rust errors with Lua ones, we pre-allocate enough memory
-  // to store a wrapped error or panic *before* we proceed.
-  lua_newuserdata(L, max(MLUA_WRAPPED_ERROR_SIZE, MLUA_WRAPPED_PANIC_SIZE));
-  lua_rotate(L, 1, 1);
-
-  lua_CFunction rust_callback = lua_touserdata(L, lua_upvalueindex(1));
-
-  int ret = rust_callback(L);
-  if (ret < 0) {
-    if (ret == -1 /* WrappedError */) {
-      handle_wrapped_error(L);
-    }
-    lua_error(L);
-  }
-
-  return ret;
-}
-
-void lua_call_mlua_hook_proc(lua_State *L, lua_Debug *ar) {
-  luaL_checkstack(L, 2, "not enough stack space for callback error handling");
-  lua_newuserdata(L, max(MLUA_WRAPPED_ERROR_SIZE, MLUA_WRAPPED_PANIC_SIZE));
-  lua_rotate(L, 1, 1);
-  int ret = mlua_hook_proc(L, ar);
-  if (ret < 0) {
-    if (ret == -1 /* WrappedError */) {
-      handle_wrapped_error(L);
-    }
-    lua_error(L);
-  }
-}
-
-static inline lua_Integer lua_popinteger(lua_State *L) {
-  lua_Integer index = lua_tointeger(L, -1);
-  lua_pop(L, 1);
-  return index;
-}
-
-//
-// Common functions
-//
-
-int lua_gc_s(lua_State *L) {
-  int data = lua_popinteger(L);
-  int what = lua_popinteger(L);
-  int ret = lua_gc(L, what, data);
-  lua_pushinteger(L, ret);
-  return 1;
-}
-
-int luaL_ref_s(lua_State *L) {
-  int ret = luaL_ref(L, -2);
-  lua_pushinteger(L, ret);
-  return 1;
-}
-
-int lua_pushlstring_s(lua_State *L) {
-  StringArg *s = lua_touserdata(L, -1);
-  lua_pop(L, 1);
-  lua_pushlstring(L, s->data, s->len);
-  return 1;
-}
-
-int lua_tolstring_s(lua_State *L) {
-  void *len = lua_touserdata(L, -1);
-  lua_pop(L, 1);
-  const char *s = lua_tolstring(L, -1, len);
-  lua_pushlightuserdata(L, (void *)s);
-  return 2;
-}
-
-int lua_newthread_s(lua_State *L) {
-  lua_newthread(L);
-  return 1;
-}
-
-int lua_newuserdata_s(lua_State *L) {
-  size_t size = lua_tointeger(L, -1);
-  lua_pop(L, 1);
-  lua_newuserdata(L, size);
-  return 1;
-}
-
-int lua_newwrappederror_s(lua_State *L) {
-  lua_newuserdata(L, MLUA_WRAPPED_ERROR_SIZE);
-  return 1;
-}
-
-int lua_pushcclosure_s(lua_State *L) {
-  int n = lua_gettop(L) - 1;
-  lua_CFunction fn = lua_touserdata(L, -1);
-  lua_pop(L, 1);
-  lua_pushcclosure(L, fn, n);
-  return 1;
-}
-
-int lua_pushrclosure_s(lua_State *L) {
-  int n = lua_gettop(L);
-  lua_pushcclosure(L, lua_call_rust, n);
-  return 1;
-}
-
-int luaL_requiref_s(lua_State *L) {
-  const char *modname = lua_touserdata(L, -3);
-  lua_CFunction openf = lua_touserdata(L, -2);
-  int glb = lua_tointeger(L, -1);
-  lua_pop(L, 3);
-  luaL_requiref(L, modname, openf, glb);
-  return 1;
-}
-
-//
-// Table functions
-//
-
-int lua_newtable_s(lua_State *L) {
-  lua_createtable(L, 0, 0);
-  return 1;
-}
-
-int lua_createtable_s(lua_State *L) {
-  int nrec = lua_popinteger(L);
-  int narr = lua_popinteger(L);
-  lua_createtable(L, narr, nrec);
-  return 1;
-}
-
-int lua_gettable_s(lua_State *L) {
-  lua_gettable(L, -2);
-  return 1;
-}
-
-int lua_settable_s(lua_State *L) {
-  lua_settable(L, -3);
-  return 0;
-}
-
-int lua_geti_s(lua_State *L) {
-  lua_Integer index = lua_popinteger(L);
-  lua_geti(L, -1, index);
-  return 1;
-}
-
-int lua_rawset_s(lua_State *L) {
-  lua_rawset(L, -3);
-  return 0;
-}
-
-int lua_rawseti_s(lua_State *L) {
-  lua_Integer index = lua_popinteger(L);
-  lua_rawseti(L, -2, index);
-  return 0;
-}
-
-int lua_rawsetp_s(lua_State *L) {
-  void *p = lua_touserdata(L, -1);
-  lua_pop(L, 1);
-  lua_rawsetp(L, -2, p);
-  return 0;
-}
-
-int lua_rawsetfield_s(lua_State *L) {
-  StringArg *s = lua_touserdata(L, -2);
-  lua_pushlstring(L, s->data, s->len);
-  lua_replace(L, -3);
-  lua_rawset(L, -3);
-  return 0;
-}
-
-int lua_rawinsert_s(lua_State *L) {
-  lua_Integer index = lua_popinteger(L);
-  lua_Integer size = lua_rawlen(L, -2);
-
-  for (lua_Integer i = size; i >= index; i--) {
-    // table[i+1] = table[i]
-    lua_rawgeti(L, -2, i);
-    lua_rawseti(L, -3, i + 1);
-  }
-  lua_rawseti(L, -2, index);
-
-  return 0;
-}
-
-int lua_rawremove_s(lua_State *L) {
-  lua_Integer index = lua_popinteger(L);
-  lua_Integer size = lua_rawlen(L, -1);
-
-  for (lua_Integer i = index; i < size; i++) {
-    lua_rawgeti(L, -1, i + 1);
-    lua_rawseti(L, -2, i);
-  }
-  lua_pushnil(L);
-  lua_rawseti(L, -2, size);
-
-  return 0;
-}
-
-int luaL_len_s(lua_State *L) {
-  lua_pushinteger(L, luaL_len(L, -1));
-  return 1;
-}
-
-int lua_next_s(lua_State *L) {
-  int ret = lua_next(L, -2);
-  lua_pushinteger(L, ret);
-  return ret == 0 ? 1 : 3;
-}
-
-//
-// Moved from Rust to C
-//
-
-// Wrapper to lookup in `field_getters` first, then `methods`, ending
-// original `__index`. Used only if `field_getters` or `methods` set.
-int meta_index_impl(lua_State *state) {
-  // stack: self, key
-  luaL_checkstack(state, 2, NULL);
-
-  // lookup in `field_getters` table
-  if (lua_isnil(state, lua_upvalueindex(2)) == 0) {
-    lua_pushvalue(state, -1); // `key` arg
-    if (lua_rawget(state, lua_upvalueindex(2)) != LUA_TNIL) {
-      lua_insert(state, -3); // move function
-      lua_pop(state, 1);     // remove `key`
-      lua_call(state, 1, 1);
-      return 1;
-    }
-    lua_pop(state, 1); // pop the nil value
-  }
-  // lookup in `methods` table
-  if (lua_isnil(state, lua_upvalueindex(3)) == 0) {
-    lua_pushvalue(state, -1); // `key` arg
-    if (lua_rawget(state, lua_upvalueindex(3)) != LUA_TNIL) {
-      lua_insert(state, -3);
-      lua_pop(state, 2);
-      return 1;
-    }
-    lua_pop(state, 1); // pop the nil value
-  }
-
-  // lookup in `__index`
-  lua_pushvalue(state, lua_upvalueindex(1));
-  switch (lua_type(state, -1)) {
-  case LUA_TNIL:
-    lua_pop(state, 1); // pop the nil value
-    const char *field = lua_tostring(state, -1);
-    luaL_error(state, "attempt to get an unknown field '%s'", field);
-    break;
-
-  case LUA_TTABLE:
-    lua_insert(state, -2);
-    lua_gettable(state, -2);
-    break;
-
-  case LUA_TFUNCTION:
-    lua_insert(state, -3);
-    lua_call(state, 2, 1);
-    break;
-  }
-
-  return 1;
-}
-
-// Similar to `meta_index_impl`, checks `field_setters` table first, then
-// `__newindex` metamethod. Used only if `field_setters` set.
-int meta_newindex_impl(lua_State *state) {
-  // stack: self, key, value
-  luaL_checkstack(state, 2, NULL);
-
-  // lookup in `field_setters` table
-  lua_pushvalue(state, -2); // `key` arg
-  if (lua_rawget(state, lua_upvalueindex(2)) != LUA_TNIL) {
-    lua_remove(state, -3); // remove `key`
-    lua_insert(state, -3); // move function
-    lua_call(state, 2, 0);
-    return 0;
-  }
-  lua_pop(state, 1); // pop the nil value
-
-  // lookup in `__newindex`
-  lua_pushvalue(state, lua_upvalueindex(1));
-  switch (lua_type(state, -1)) {
-  case LUA_TNIL:
-    lua_pop(state, 1); // pop the nil value
-    const char *field = lua_tostring(state, -2);
-    luaL_error(state, "attempt to set an unknown field '%s'", field);
-    break;
-
-  case LUA_TTABLE:
-    lua_insert(state, -3);
-    lua_settable(state, -3);
-    break;
-
-  case LUA_TFUNCTION:
-    lua_insert(state, -4);
-    lua_call(state, 3, 0);
-    break;
-  }
-
-  return 0;
-}
-
-// See Function::bind
-int bind_call_impl(lua_State *state) {
-  int nargs = lua_gettop(state);
-  int nbinds = lua_tointeger(state, lua_upvalueindex(2));
-  luaL_checkstack(state, nbinds + 2, NULL);
-
-  lua_settop(state, nargs + nbinds + 1);
-  lua_rotate(state, -(nargs + nbinds + 1), nbinds + 1);
-
-  lua_pushvalue(state, lua_upvalueindex(1));
-  lua_replace(state, 1);
-
-  for (int i = 0; i < nbinds; i++) {
-    lua_pushvalue(state, lua_upvalueindex(i + 3));
-    lua_replace(state, i + 2);
-  }
-
-  lua_call(state, nargs + nbinds, LUA_MULTRET);
-  return lua_gettop(state);
-}
-
-// Returns 1 if a value at index `index` is a special wrapped struct identified
-// by `key`
-int is_wrapped_struct(lua_State *state, int index, const void *key) {
-  if (key == NULL) {
-    // Not yet initialized?
-    return 0;
-  }
-
-  void *ud = lua_touserdata(state, index);
-  if (ud == NULL || lua_getmetatable(state, index) == 0) {
-    return 0;
-  }
-  lua_rawgetp(state, LUA_REGISTRYINDEX, key);
-  int res = lua_rawequal(state, -1, -2);
-  lua_pop(state, 2);
-  return res;
-}
-
-// Takes an error at the top of the stack and converts Lua errors into a string
-// with attached traceback. If the error is a WrappedError or WrappedPanic, does
-// not modify it. This function does its best to avoid triggering another error
-// and shadowing previous rust errors.
-int error_traceback(lua_State *state) {
-  if (lua_checkstack(state, 2) == 0) {
-    // If we don't have enough stack space to even check the error type, do
-    // nothing so we don't risk shadowing a rust panic.
-    return 1;
-  }
-
-  if (MLUA_WRAPPED_PANIC_KEY == NULL ||
-      is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY) ||
-      is_wrapped_struct(state, -1, MLUA_WRAPPED_ERROR_KEY)) {
-    return 1;
-  }
-
-  const char *s = luaL_tolstring(state, -1, NULL);
-  if (lua_checkstack(state, LUA_TRACEBACK_STACK) != 0) {
-    luaL_traceback(state, state, s, 1);
-    lua_remove(state, -2);
-  }
-
-  return 1;
-}
-
-int error_traceback_s(lua_State *L) {
-  lua_State *L1 = lua_touserdata(L, -1);
-  lua_pop(L, 1);
-  return error_traceback(L1);
-}
-
-// A `pcall` implementation that does not allow Lua to catch Rust panics.
-// Instead, panics automatically resumed.
-int lua_nopanic_pcall(lua_State *state) {
-  luaL_checkstack(state, 2, NULL);
-
-  int top = lua_gettop(state);
-  if (top == 0) {
-    lua_pushstring(state, "not enough arguments to pcall");
-    lua_error(state);
-  }
-
-  if (lua_pcall(state, top - 1, LUA_MULTRET, 0) == LUA_OK) {
-    lua_pushboolean(state, 1);
-    lua_insert(state, 1);
-    return lua_gettop(state);
-  }
-
-  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY)) {
-    lua_error(state);
-  }
-  lua_pushboolean(state, 0);
-  lua_insert(state, -2);
-  return 2;
-}
-
-// A `xpcall` implementation that does not allow Lua to catch Rust panics.
-// Instead, panics automatically resumed.
-
-static int xpcall_msgh(lua_State *state) {
-  luaL_checkstack(state, 2, NULL);
-  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY)) {
-    return 1;
-  }
-  lua_pushvalue(state, lua_upvalueindex(1));
-  lua_insert(state, 1);
-  lua_call(state, lua_gettop(state) - 1, LUA_MULTRET);
-  return lua_gettop(state);
-}
-
-int lua_nopanic_xpcall(lua_State *state) {
-  luaL_checkstack(state, 2, NULL);
-
-  int top = lua_gettop(state);
-  if (top < 2) {
-    lua_pushstring(state, "not enough arguments to xpcall");
-    lua_error(state);
-  }
-
-  lua_pushvalue(state, 2);
-  lua_pushcclosure(state, xpcall_msgh, 1);
-  lua_copy(state, 1, 2);
-  lua_replace(state, 1);
-
-  if (lua_pcall(state, lua_gettop(state) - 2, LUA_MULTRET, 1) == LUA_OK) {
-    lua_pushboolean(state, 1);
-    lua_insert(state, 2);
-    return lua_gettop(state) - 1;
-  }
-
-  if (is_wrapped_struct(state, -1, MLUA_WRAPPED_PANIC_KEY)) {
-    lua_error(state);
-  }
-  lua_pushboolean(state, 0);
-  lua_insert(state, -2);
-  return 2;
-}

src/function.rs

@@ -1,10 +1,11 @@
 use std::os::raw::{c_int, c_void};
+use std::ptr;
 use std::slice;
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::types::LuaRef;
-use crate::util::{assert_stack, check_stack, pop_error, StackGuard};
+use crate::util::{assert_stack, check_stack, error_traceback, pop_error, protect_lua, StackGuard};
 use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
 
 #[cfg(feature = "async")]
@@ -65,7 +66,7 @@ impl<'lua> Function<'lua> {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, nargs + 3)?;
 
-            ffi::lua_pushcfunction(lua.state, ffi::safe::error_traceback);
+            ffi::lua_pushcfunction(lua.state, error_traceback);
             let stack_start = ffi::lua_gettop(lua.state);
             lua.push_ref(&self.0);
             for arg in args {
@@ -159,6 +160,26 @@ impl<'lua> Function<'lua> {
     /// # }
     /// ```
     pub fn bind<A: ToLuaMulti<'lua>>(&self, args: A) -> Result<Function<'lua>> {
+        unsafe extern "C" fn bind_call_impl(state: *mut ffi::lua_State) -> c_int {
+            let nargs = ffi::lua_gettop(state);
+            let nbinds = ffi::lua_tointeger(state, ffi::lua_upvalueindex(2)) as c_int;
+            ffi::luaL_checkstack(state, nbinds + 2, ptr::null());
+
+            ffi::lua_settop(state, nargs + nbinds + 1);
+            ffi::lua_rotate(state, -(nargs + nbinds + 1), nbinds + 1);
+
+            ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
+            ffi::lua_replace(state, 1);
+
+            for i in 0..nbinds {
+                ffi::lua_pushvalue(state, ffi::lua_upvalueindex(i + 3));
+                ffi::lua_replace(state, i + 2);
+            }
+
+            ffi::lua_call(state, nargs + nbinds, ffi::LUA_MULTRET);
+            ffi::lua_gettop(state)
+        }
+
         let lua = self.0.lua;
 
         let args = args.to_lua_multi(lua)?;
@@ -177,7 +198,9 @@ impl<'lua> Function<'lua> {
             for arg in args {
                 lua.push_value(arg)?;
             }
-            ffi::safe::lua_pushcclosure(lua.state, ffi::safe::bind_call_impl, nargs + 2)?;
+            protect_lua(lua.state, nargs + 2, 1, |state| {
+                ffi::lua_pushcclosure(state, bind_call_impl, nargs + 2);
+            })?;
 
             Ok(Function(lua.pop_ref()))
         }

src/hook.rs

@@ -165,8 +165,7 @@ impl HookTriggers {
     }
 }
 
-#[no_mangle]
-pub unsafe extern "C" fn mlua_hook_proc(state: *mut lua_State, ar: *mut lua_Debug) -> c_int {
+pub(crate) unsafe extern "C" fn hook_proc(state: *mut lua_State, ar: *mut lua_Debug) {
     callback_error(state, |_| {
         let debug = Debug {
             ar,
@@ -174,7 +173,7 @@ pub unsafe extern "C" fn mlua_hook_proc(state: *mut lua_State, ar: *mut lua_Debu
             _phantom: PhantomData,
         };
 
-        let lua = Lua::make_from_ptr(state);
+        let lua = mlua_expect!(Lua::make_from_ptr(state), "cannot make Lua instance");
         let hook_cb = mlua_expect!(lua.hook_callback(), "no hook callback set in hook_proc");
 
         #[allow(clippy::match_wild_err_arm)]
@@ -183,7 +182,7 @@ pub unsafe extern "C" fn mlua_hook_proc(state: *mut lua_State, ar: *mut lua_Debu
             Err(_) => mlua_panic!("Lua should not allow hooks to be called within another hook"),
         }?;
 
-        Ok(0)
+        Ok(())
     })
 }
 

src/lib.rs

@@ -72,7 +72,7 @@
 //! [`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
 
 // mlua types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/mlua/0.6.0-beta.2")]
+#![doc(html_root_url = "https://docs.rs/mlua/0.6.1")]
 // Deny warnings inside doc tests / examples. When this isn't present, rustdoc doesn't show *any*
 // warnings at all.
 #![doc(test(attr(deny(warnings))))]
@@ -139,9 +139,9 @@ extern crate mlua_derive;
 /// This macro allows to write Lua code directly in Rust code.
 ///
 /// Rust variables can be referenced from Lua using `$` prefix, as shown in the example below.
-/// User Rust types needs to implement [`UserData`] or [`ToLua`] traits.
+/// User's Rust types needs to implement [`UserData`] or [`ToLua`] traits.
 ///
-/// Captured variables are moved into the chunk.
+/// Captured variables are **moved** into the chunk.
 ///
 /// ```
 /// use mlua::{Lua, Result, chunk};
@@ -165,12 +165,19 @@ extern crate mlua_derive;
 ///   (Single quoted strings only work if they contain a single character, since in Rust,
 ///   `'a'` is a character literal).
 ///
+/// - Using Lua comments `--` is not desirable in **stable** Rust and can have bad side effects.
+///
+///   This is because procedural macros have Line/Column information available only in
+///   **nightly** Rust. Instead, Lua chunks represented as a big single line of code in stable Rust.
+///
+///   As workaround, Rust comments `//` can be used.
+///
 /// Other minor limitations:
 ///
-/// - Certain escape codes in string literals.
+/// - Certain escape codes in string literals don't work.
 ///   (Specifically: `\a`, `\b`, `\f`, `\v`, `\123` (octal escape codes), `\u`, and `\U`).
 ///
-///   These are accepted: : `\\`, `\n`, `\t`, `\r`, `\xAB` (hex escape codes), and `\0`
+///   These are accepted: : `\\`, `\n`, `\t`, `\r`, `\xAB` (hex escape codes), and `\0`.
 ///
 /// - The `//` (floor division) operator is unusable, as its start a comment.
 ///

src/scope.rs

@@ -1,8 +1,10 @@
 use std::any::Any;
-use std::cell::{Cell, Ref, RefCell, RefMut};
+use std::cell::{Cell, RefCell};
 use std::marker::PhantomData;
 use std::mem;
 use std::os::raw::{c_int, c_void};
+use std::ptr;
+use std::rc::Rc;
 
 #[cfg(feature = "serialize")]
 use serde::Serialize;
@@ -16,8 +18,8 @@ use crate::userdata::{
     AnyUserData, MetaMethod, UserData, UserDataCell, UserDataFields, UserDataMethods,
 };
 use crate::util::{
-    assert_stack, check_stack, get_userdata, init_userdata_metatable, push_userdata, take_userdata,
-    StackGuard,
+    assert_stack, check_stack, get_userdata, init_userdata_metatable, protect_lua, push_table,
+    rawset_field, take_userdata, StackGuard,
 };
 use crate::value::{FromLua, FromLuaMulti, MultiValue, ToLua, ToLuaMulti, Value};
 
@@ -238,7 +240,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
     where
         T: 'scope + UserData,
     {
-        let data = UserDataCell::new_arc(data);
+        let data = Rc::new(RefCell::new(data));
 
         // 'callback outliving 'scope is a lie to make the types work out, required due to the
         // inability to work with the more correct callback type that is universally quantified over
@@ -247,7 +249,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
         // parameters.
         fn wrap_method<'scope, 'lua, 'callback: 'scope, T: 'scope>(
             scope: &Scope<'lua, 'scope>,
-            data: UserDataCell<T>,
+            data: Rc<RefCell<T>>,
             data_ptr: *mut c_void,
             method: NonStaticMethod<'callback, T>,
         ) -> Result<Function<'lua>> {
@@ -263,7 +265,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
                     unsafe {
                         let _sg = StackGuard::new(lua.state);
                         check_stack(lua.state, 3)?;
-                        lua.push_userdata_ref(&ud.0)?;
+                        lua.push_userdata_ref(&ud.0, false)?;
                         if get_userdata(lua.state, -1) == data_ptr {
                             return Ok(());
                         }
@@ -276,10 +278,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
                 NonStaticMethod::Method(method) => {
                     let f = Box::new(move |lua, mut args: MultiValue<'callback>| {
                         check_ud_type(lua, args.pop_front())?;
-                        let data = data
-                            .try_borrow()
-                            .map(|cell| Ref::map(cell, AsRef::as_ref))
-                            .map_err(|_| Error::UserDataBorrowError)?;
+                        let data = data.try_borrow().map_err(|_| Error::UserDataBorrowError)?;
                         method(lua, &*data, args)
                     });
                     unsafe { scope.create_callback(f) }
@@ -293,7 +292,6 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
                             .map_err(|_| Error::RecursiveMutCallback)?;
                         let mut data = data
                             .try_borrow_mut()
-                            .map(|cell| RefMut::map(cell, AsMut::as_mut))
                             .map_err(|_| Error::UserDataBorrowMutError)?;
                         (&mut *method)(lua, &mut *data, args)
                     });
@@ -324,32 +322,32 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, 13)?;
 
-            push_userdata(lua.state, data.clone())?;
-            let data_ptr = ffi::lua_touserdata(lua.state, -1);
-
+            let data_ptr = protect_lua(lua.state, 0, 1, |state| {
+                ffi::lua_newuserdata(state, mem::size_of::<UserDataCell<Rc<RefCell<T>>>>())
+            })?;
             // Prepare metatable, add meta methods first and then meta fields
             let meta_methods_nrec = ud_methods.meta_methods.len() + ud_fields.meta_fields.len() + 1;
-            ffi::safe::lua_createtable(lua.state, 0, meta_methods_nrec as c_int)?;
+            push_table(lua.state, 0, meta_methods_nrec as c_int)?;
 
             for (k, m) in ud_methods.meta_methods {
                 let data = data.clone();
                 lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
-                ffi::safe::lua_rawsetfield(lua.state, -2, k.validate()?.name())?;
+                rawset_field(lua.state, -2, k.validate()?.name())?;
             }
             for (k, f) in ud_fields.meta_fields {
                 lua.push_value(f(mem::transmute(lua))?)?;
-                ffi::safe::lua_rawsetfield(lua.state, -2, k.validate()?.name())?;
+                rawset_field(lua.state, -2, k.validate()?.name())?;
             }
             let metatable_index = ffi::lua_absindex(lua.state, -1);
 
             let mut field_getters_index = None;
             let field_getters_nrec = ud_fields.field_getters.len();
             if field_getters_nrec > 0 {
-                ffi::safe::lua_createtable(lua.state, 0, field_getters_nrec as c_int)?;
+                push_table(lua.state, 0, field_getters_nrec as c_int)?;
                 for (k, m) in ud_fields.field_getters {
                     let data = data.clone();
                     lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
-                    ffi::safe::lua_rawsetfield(lua.state, -2, &k)?;
+                    rawset_field(lua.state, -2, &k)?;
                 }
                 field_getters_index = Some(ffi::lua_absindex(lua.state, -1));
             }
@@ -357,11 +355,11 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             let mut field_setters_index = None;
             let field_setters_nrec = ud_fields.field_setters.len();
             if field_setters_nrec > 0 {
-                ffi::safe::lua_createtable(lua.state, 0, field_setters_nrec as c_int)?;
+                push_table(lua.state, 0, field_setters_nrec as c_int)?;
                 for (k, m) in ud_fields.field_setters {
                     let data = data.clone();
                     lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
-                    ffi::safe::lua_rawsetfield(lua.state, -2, &k)?;
+                    rawset_field(lua.state, -2, &k)?;
                 }
                 field_setters_index = Some(ffi::lua_absindex(lua.state, -1));
             }
@@ -370,16 +368,16 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             let methods_nrec = ud_methods.methods.len();
             if methods_nrec > 0 {
                 // Create table used for methods lookup
-                ffi::safe::lua_createtable(lua.state, 0, methods_nrec as c_int)?;
+                push_table(lua.state, 0, methods_nrec as c_int)?;
                 for (k, m) in ud_methods.methods {
                     let data = data.clone();
                     lua.push_value(Value::Function(wrap_method(self, data, data_ptr, m)?))?;
-                    ffi::safe::lua_rawsetfield(lua.state, -2, &k)?;
+                    rawset_field(lua.state, -2, &k)?;
                 }
                 methods_index = Some(ffi::lua_absindex(lua.state, -1));
             }
 
-            init_userdata_metatable::<()>(
+            init_userdata_metatable::<UserDataCell<Rc<RefCell<T>>>>(
                 lua.state,
                 metatable_index,
                 field_getters_index,
@@ -393,6 +391,8 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             ffi::lua_pop(lua.state, count);
 
             let mt_id = ffi::lua_topointer(lua.state, -1);
+            // Write userdata just before attaching metatable with `__gc` metamethod
+            ptr::write(data_ptr as _, UserDataCell::new(data));
             ffi::lua_setmetatable(lua.state, -2);
             let ud = AnyUserData(lua.pop_ref());
             lua.register_userdata_metatable(mt_id as isize);
@@ -427,7 +427,8 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
                     mem::transmute(f)
                 }
 
-                vec![Box::new(seal(take_userdata::<UserDataCell<T>>(state)))]
+                let ud = Box::new(seal(take_userdata::<UserDataCell<Rc<RefCell<T>>>>(state)));
+                vec![ud]
             });
             self.destructors
                 .borrow_mut()
@@ -458,15 +459,15 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
 
             // We know the destructor has not run yet because we hold a reference to the callback.
 
-            ffi::lua_getupvalue(state, -1, 2);
+            ffi::lua_getupvalue(state, -1, 1);
             let ud1 = take_userdata::<Callback>(state);
             ffi::lua_pushnil(state);
-            ffi::lua_setupvalue(state, -2, 2);
+            ffi::lua_setupvalue(state, -2, 1);
 
-            ffi::lua_getupvalue(state, -1, 3);
+            ffi::lua_getupvalue(state, -1, 2);
             let ud2 = take_userdata::<Lua>(state);
             ffi::lua_pushnil(state);
-            ffi::lua_setupvalue(state, -2, 3);
+            ffi::lua_setupvalue(state, -2, 2);
 
             vec![Box::new(ud1), Box::new(ud2)]
         });
@@ -508,15 +509,15 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             ffi::lua_rawget(state, -2);
 
             // Destroy all upvalues
-            ffi::lua_getupvalue(state, -1, 2);
+            ffi::lua_getupvalue(state, -1, 1);
             let ud1 = take_userdata::<AsyncCallback>(state);
             ffi::lua_pushnil(state);
-            ffi::lua_setupvalue(state, -2, 2);
+            ffi::lua_setupvalue(state, -2, 1);
 
-            ffi::lua_getupvalue(state, -1, 3);
+            ffi::lua_getupvalue(state, -1, 2);
             let ud2 = take_userdata::<Lua>(state);
             ffi::lua_pushnil(state);
-            ffi::lua_setupvalue(state, -2, 3);
+            ffi::lua_setupvalue(state, -2, 2);
 
             ffi::lua_pop(state, 1);
             let mut data: Vec<Box<dyn Any>> = vec![Box::new(ud1), Box::new(ud2)];
@@ -524,16 +525,16 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
             // Finally, get polled future and destroy it
             f.lua.push_ref(&poll_str.0);
             if ffi::lua_rawget(state, -2) == ffi::LUA_TFUNCTION {
-                ffi::lua_getupvalue(state, -1, 2);
+                ffi::lua_getupvalue(state, -1, 1);
                 let ud3 = take_userdata::<LocalBoxFuture<Result<MultiValue>>>(state);
                 ffi::lua_pushnil(state);
-                ffi::lua_setupvalue(state, -2, 2);
+                ffi::lua_setupvalue(state, -2, 1);
                 data.push(Box::new(ud3));
 
-                ffi::lua_getupvalue(state, -1, 3);
+                ffi::lua_getupvalue(state, -1, 2);
                 let ud4 = take_userdata::<Lua>(state);
                 ffi::lua_pushnil(state);
-                ffi::lua_setupvalue(state, -2, 3);
+                ffi::lua_setupvalue(state, -2, 2);
                 data.push(Box::new(ud4));
             }
 
@@ -665,7 +666,6 @@ impl<'lua, T: UserData> UserDataMethods<'lua, T> for NonStaticUserDataMethods<'l
     #[cfg(feature = "async")]
     fn add_async_function<S, A, R, F, FR>(&mut self, _name: &S, _function: F)
     where
-        T: Clone,
         S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,

src/serde/mod.rs

@@ -10,7 +10,7 @@ use crate::ffi;
 use crate::lua::Lua;
 use crate::table::Table;
 use crate::types::LightUserData;
-use crate::util::{assert_stack, check_stack, StackGuard};
+use crate::util::{assert_stack, check_stack, protect_lua, StackGuard};
 use crate::value::Value;
 
 /// Trait for serializing/deserializing Lua values using Serde.
@@ -200,15 +200,17 @@ impl<'lua> LuaSerdeExt<'lua> for Lua {
 
 // Uses 6 stack spaces and calls checkstack.
 pub(crate) unsafe fn init_metatables(state: *mut ffi::lua_State) -> Result<()> {
-    check_stack(state, 6)?;
+    check_stack(state, 3)?;
+    protect_lua(state, 0, 0, |state| {
+        ffi::lua_createtable(state, 0, 1);
 
-    ffi::safe::lua_createtable(state, 0, 1)?;
+        ffi::lua_pushstring(state, cstr!("__metatable"));
+        ffi::lua_pushboolean(state, 0);
+        ffi::lua_rawset(state, -3);
 
-    ffi::lua_pushboolean(state, 0);
-    ffi::safe::lua_rawsetfield(state, -2, "__metatable")?;
-
-    let array_metatable_key = &ARRAY_METATABLE_REGISTRY_KEY as *const u8 as *const c_void;
-    ffi::safe::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, array_metatable_key)
+        let array_metatable_key = &ARRAY_METATABLE_REGISTRY_KEY as *const u8 as *const c_void;
+        ffi::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, array_metatable_key);
+    })
 }
 
 pub(crate) unsafe fn push_array_metatable(state: *mut ffi::lua_State) {

src/serde/ser.rs

@@ -9,7 +9,7 @@ use crate::lua::Lua;
 use crate::string::String;
 use crate::table::Table;
 use crate::types::Integer;
-use crate::util::{check_stack, StackGuard};
+use crate::util::{check_stack, protect_lua, StackGuard};
 use crate::value::{ToLua, Value};
 
 /// A struct for serializing Rust values into Lua values.
@@ -318,12 +318,14 @@ impl<'lua> ser::SerializeSeq for SerializeVec<'lua> {
         let value = lua.to_value_with(value, self.options)?;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 6)?;
+            check_stack(lua.state, 5)?;
 
             lua.push_ref(&self.table.0);
             lua.push_value(value)?;
             let len = ffi::lua_rawlen(lua.state, -2) as Integer;
-            ffi::safe::lua_rawseti(lua.state, -2, len + 1)
+            protect_lua(lua.state, 2, 0, |state| {
+                ffi::lua_rawseti(state, -2, len + 1);
+            })
         }
     }
 

src/string.rs

@@ -1,3 +1,5 @@
+use std::borrow::Cow;
+use std::string::String as StdString;
 use std::{slice, str};
 
 #[cfg(feature = "serialize")]
@@ -44,6 +46,28 @@ impl<'lua> String<'lua> {
         })
     }
 
+    /// Converts this string to a [`Cow<str>`].
+    ///
+    /// Any non-Unicode sequences are replaced with [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD].
+    ///
+    /// [U+FFFD]: std::char::REPLACEMENT_CHARACTER
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use mlua::{Lua, Result};
+    /// # fn main() -> Result<()> {
+    /// let lua = Lua::new();
+    ///
+    /// let s = lua.create_string(b"test\xff")?;
+    /// assert_eq!(s.to_string_lossy(), "test\u{fffd}");
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn to_string_lossy(&self) -> Cow<'_, str> {
+        StdString::from_utf8_lossy(self.as_bytes())
+    }
+
     /// Get the bytes that make up this string.
     ///
     /// The returned slice will not contain the terminating nul byte, but will contain any nul

src/table.rs

@@ -10,7 +10,7 @@ use crate::error::{Error, Result};
 use crate::ffi;
 use crate::function::Function;
 use crate::types::{Integer, LuaRef};
-use crate::util::{assert_stack, check_stack, StackGuard};
+use crate::util::{assert_stack, check_stack, protect_lua, StackGuard};
 use crate::value::{FromLua, FromLuaMulti, Nil, ToLua, ToLuaMulti, Value};
 
 #[cfg(feature = "async")]
@@ -67,7 +67,7 @@ impl<'lua> Table<'lua> {
             lua.push_ref(&self.0);
             lua.push_value(key)?;
             lua.push_value(value)?;
-            ffi::safe::lua_settable(lua.state, -3)
+            protect_lua(lua.state, 3, 0, |state| ffi::lua_settable(state, -3))
         }
     }
 
@@ -105,7 +105,7 @@ impl<'lua> Table<'lua> {
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
-            ffi::safe::lua_gettable(lua.state, -2)?;
+            protect_lua(lua.state, 2, 1, |state| ffi::lua_gettable(state, -2))?;
 
             lua.pop_value()
         };
@@ -123,9 +123,9 @@ impl<'lua> Table<'lua> {
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
-            ffi::safe::lua_gettable(lua.state, -2)?;
-
-            Ok(ffi::lua_isnil(lua.state, -1) == 0)
+            protect_lua(lua.state, 2, 1, |state| {
+                ffi::lua_gettable(state, -2) != ffi::LUA_TNIL
+            })
         }
     }
 
@@ -198,7 +198,7 @@ impl<'lua> Table<'lua> {
             lua.push_ref(&self.0);
             lua.push_value(key)?;
             lua.push_value(value)?;
-            ffi::safe::lua_rawset(lua.state, -3)
+            protect_lua(lua.state, 3, 0, |state| ffi::lua_rawset(state, -3))
         }
     }
 
@@ -232,11 +232,18 @@ impl<'lua> Table<'lua> {
         let value = value.to_lua(lua)?;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 6)?;
+            check_stack(lua.state, 5)?;
 
             lua.push_ref(&self.0);
             lua.push_value(value)?;
-            ffi::safe::lua_rawinsert(lua.state, -2, idx)
+            protect_lua(lua.state, 2, 0, |state| {
+                for i in (idx..=size).rev() {
+                    // table[i+1] = table[i]
+                    ffi::lua_rawgeti(state, -2, i);
+                    ffi::lua_rawseti(state, -3, i + 1);
+                }
+                ffi::lua_rawseti(state, -2, idx)
+            })
         }
     }
 
@@ -258,10 +265,17 @@ impl<'lua> Table<'lua> {
                 }
                 unsafe {
                     let _sg = StackGuard::new(lua.state);
-                    check_stack(lua.state, 5)?;
+                    check_stack(lua.state, 4)?;
 
                     lua.push_ref(&self.0);
-                    ffi::safe::lua_rawremove(lua.state, -1, idx)
+                    protect_lua(lua.state, 1, 0, |state| {
+                        for i in idx..size {
+                            ffi::lua_rawgeti(state, -1, i + 1);
+                            ffi::lua_rawseti(state, -2, i);
+                        }
+                        ffi::lua_pushnil(state);
+                        ffi::lua_rawseti(state, -2, size);
+                    })
                 }
             }
             _ => self.raw_set(key, Nil),
@@ -280,7 +294,7 @@ impl<'lua> Table<'lua> {
             check_stack(lua.state, 4)?;
 
             lua.push_ref(&self.0);
-            ffi::safe::luaL_len(lua.state, -1)
+            protect_lua(lua.state, 1, 0, |state| ffi::luaL_len(state, -1))
         }
     }
 
@@ -657,7 +671,10 @@ where
                 lua.push_ref(&self.table);
                 lua.push_value(prev_key)?;
 
-                if ffi::safe::lua_next(lua.state, -2)? != 0 {
+                let next = protect_lua(lua.state, 2, ffi::LUA_MULTRET, |state| {
+                    ffi::lua_next(state, -2)
+                })?;
+                if next != 0 {
                     let value = lua.pop_value();
                     let key = lua.pop_value();
                     Ok(Some((
@@ -709,13 +726,13 @@ where
 
             let res = (|| unsafe {
                 let _sg = StackGuard::new(lua.state);
-                check_stack(lua.state, 1 + if self.raw { 0 } else { 4 })?;
+                check_stack(lua.state, 1 + if self.raw { 0 } else { 3 })?;
 
                 lua.push_ref(&self.table);
                 let res = if self.raw {
                     ffi::lua_rawgeti(lua.state, -1, index)
                 } else {
-                    ffi::safe::lua_geti(lua.state, -1, index)?
+                    protect_lua(lua.state, 1, 1, |state| ffi::lua_geti(state, -1, index))?
                 };
                 match res {
                     ffi::LUA_TNIL if index > self.len.unwrap_or(0) => Ok(None),

src/thread.rs

@@ -4,7 +4,7 @@ use std::os::raw::c_int;
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::types::LuaRef;
-use crate::util::{assert_stack, check_stack, pop_error, StackGuard};
+use crate::util::{assert_stack, check_stack, error_traceback, pop_error, protect_lua, StackGuard};
 use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
 
 #[cfg(any(feature = "lua54", all(feature = "luajit", feature = "vendored"), doc))]
@@ -135,7 +135,7 @@ impl<'lua> Thread<'lua> {
 
             let ret = ffi::lua_resume(thread_state, lua.state, nargs, &mut nresults as *mut c_int);
             if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
-                ffi::safe::error_traceback2(lua.state, thread_state)?;
+                protect_lua(lua.state, 0, 0, |_| error_traceback(thread_state))?;
                 return Err(pop_error(thread_state, ret));
             }
 
@@ -258,7 +258,7 @@ impl<'lua> Thread<'lua> {
         A: ToLuaMulti<'lua>,
         R: FromLuaMulti<'lua>,
     {
-        let args = args.to_lua_multi(&self.0.lua);
+        let args = args.to_lua_multi(self.0.lua);
         AsyncThread {
             thread: self,
             args0: RefCell::new(Some(args)),

src/types.rs

@@ -1,4 +1,5 @@
 use std::cell::RefCell;
+use std::hash::{Hash, Hasher};
 use std::os::raw::{c_int, c_void};
 use std::sync::{Arc, Mutex};
 use std::{fmt, mem, ptr};
@@ -67,6 +68,20 @@ impl fmt::Debug for RegistryKey {
     }
 }
 
+impl Hash for RegistryKey {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.registry_id.hash(state)
+    }
+}
+
+impl PartialEq for RegistryKey {
+    fn eq(&self, other: &RegistryKey) -> bool {
+        self.registry_id == other.registry_id && Arc::ptr_eq(&self.unref_list, &other.unref_list)
+    }
+}
+
+impl Eq for RegistryKey {}
+
 impl Drop for RegistryKey {
     fn drop(&mut self) {
         let mut unref_list = mlua_expect!(self.unref_list.lock(), "unref list poisoned");
@@ -117,8 +132,8 @@ impl<'lua> PartialEq for LuaRef<'lua> {
         unsafe {
             let _sg = StackGuard::new(lua.state);
             assert_stack(lua.state, 2);
-            lua.push_ref(&self);
-            lua.push_ref(&other);
+            lua.push_ref(self);
+            lua.push_ref(other);
             ffi::lua_rawequal(lua.state, -1, -2) == 1
         }
     }

src/userdata.rs

@@ -1,9 +1,9 @@
+use std::any::TypeId;
 use std::cell::{Ref, RefCell, RefMut};
 use std::fmt;
 use std::hash::{Hash, Hasher};
-use std::ops::Deref;
+use std::ops::{Deref, DerefMut};
 use std::string::String as StdString;
-use std::sync::Arc;
 
 #[cfg(feature = "async")]
 use std::future::Future;
@@ -19,13 +19,18 @@ use crate::ffi;
 use crate::function::Function;
 use crate::lua::Lua;
 use crate::table::{Table, TablePairs};
-use crate::types::{LuaRef, MaybeSend};
-use crate::util::{check_stack, get_destructed_userdata_metatable, get_userdata, StackGuard};
+use crate::types::{Callback, LuaRef, MaybeSend};
+use crate::util::{
+    check_stack, get_destructed_userdata_metatable, get_userdata, push_string, StackGuard,
+};
 use crate::value::{FromLua, FromLuaMulti, ToLua, ToLuaMulti};
 
 #[cfg(any(feature = "lua52", feature = "lua51", feature = "luajit"))]
 use crate::value::Value;
 
+#[cfg(feature = "async")]
+use crate::types::AsyncCallback;
+
 /// Kinds of metamethods that can be overridden.
 ///
 /// Currently, this mechanism does not allow overriding the `__gc` metamethod, since there is
@@ -101,6 +106,15 @@ pub enum MetaMethod {
     /// Requires `feature = "lua54/lua53/lua52"`
     #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52", doc))]
     Pairs,
+    /// The `__ipairs` metamethod.
+    ///
+    /// This is not an operator, but it will be called by the built-in [`ipairs`] function.
+    ///
+    /// Requires `feature = "lua52"`
+    ///
+    /// [`ipairs`]: https://www.lua.org/manual/5.2/manual.html#pdf-ipairs
+    #[cfg(any(feature = "lua52", doc))]
+    IPairs,
     /// The `__close` metamethod.
     ///
     /// Executed when a variable, that marked as to-be-closed, goes out of scope.
@@ -178,6 +192,8 @@ impl MetaMethod {
 
             #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
             MetaMethod::Pairs => "__pairs",
+            #[cfg(feature = "lua52")]
+            MetaMethod::IPairs => "__ipairs",
 
             #[cfg(feature = "lua54")]
             MetaMethod::Close => "__close",
@@ -238,6 +254,8 @@ impl From<StdString> for MetaMethod {
 
             #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
             "__pairs" => MetaMethod::Pairs,
+            #[cfg(feature = "lua52")]
+            "__ipairs" => MetaMethod::IPairs,
 
             #[cfg(feature = "lua54")]
             "__close" => MetaMethod::Close,
@@ -343,7 +361,6 @@ pub trait UserDataMethods<'lua, T: UserData> {
     #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
     fn add_async_function<S, A, R, F, FR>(&mut self, name: &S, function: F)
     where
-        T: Clone,
         S: AsRef<[u8]> + ?Sized,
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
@@ -403,6 +420,20 @@ pub trait UserDataMethods<'lua, T: UserData> {
         A: FromLuaMulti<'lua>,
         R: ToLuaMulti<'lua>,
         F: 'static + MaybeSend + FnMut(&'lua Lua, A) -> Result<R>;
+
+    //
+    // Below are internal methods used in generated code
+    //
+
+    #[doc(hidden)]
+    fn add_callback(&mut self, _name: Vec<u8>, _callback: Callback<'lua, 'static>) {}
+
+    #[doc(hidden)]
+    #[cfg(feature = "async")]
+    fn add_async_callback(&mut self, _name: Vec<u8>, _callback: AsyncCallback<'lua, 'static>) {}
+
+    #[doc(hidden)]
+    fn add_meta_callback(&mut self, _meta: MetaMethod, _callback: Callback<'lua, 'static>) {}
 }
 
 /// Field registry for [`UserData`] implementors.
@@ -474,6 +505,16 @@ pub trait UserDataFields<'lua, T: UserData> {
         S: Into<MetaMethod>,
         F: 'static + MaybeSend + Fn(&'lua Lua) -> Result<R>,
         R: ToLua<'lua>;
+
+    //
+    // Below are internal methods used in generated code
+    //
+
+    #[doc(hidden)]
+    fn add_field_getter(&mut self, _name: Vec<u8>, _callback: Callback<'lua, 'static>) {}
+
+    #[doc(hidden)]
+    fn add_field_setter(&mut self, _name: Vec<u8>, _callback: Callback<'lua, 'static>) {}
 }
 
 /// Trait for custom userdata types.
@@ -550,26 +591,11 @@ pub trait UserData: Sized {
 }
 
 // Wraps UserData in a way to always implement `serde::Serialize` trait.
-pub(crate) enum UserDataCell<T> {
-    Arc(Arc<RefCell<UserDataWrapped<T>>>),
-    Plain(RefCell<UserDataWrapped<T>>),
-}
+pub(crate) struct UserDataCell<T>(RefCell<UserDataWrapped<T>>);
 
 impl<T> UserDataCell<T> {
     pub(crate) fn new(data: T) -> Self {
-        UserDataCell::Plain(RefCell::new(UserDataWrapped {
-            data: Box::into_raw(Box::new(data)),
-            #[cfg(feature = "serialize")]
-            ser: Box::into_raw(Box::new(UserDataSerializeError)),
-        }))
-    }
-
-    pub(crate) fn new_arc(data: T) -> Self {
-        UserDataCell::Arc(Arc::new(RefCell::new(UserDataWrapped {
-            data: Box::into_raw(Box::new(data)),
-            #[cfg(feature = "serialize")]
-            ser: Box::into_raw(Box::new(UserDataSerializeError)),
-        })))
+        UserDataCell(RefCell::new(UserDataWrapped::new(data)))
     }
 
     #[cfg(feature = "serialize")]
@@ -577,40 +603,135 @@ impl<T> UserDataCell<T> {
     where
         T: 'static + Serialize,
     {
-        let data_raw = Box::into_raw(Box::new(data));
-        UserDataCell::Plain(RefCell::new(UserDataWrapped {
-            data: data_raw,
-            ser: data_raw,
-        }))
+        UserDataCell(RefCell::new(UserDataWrapped::new_ser(data)))
+    }
+
+    // Immutably borrows the wrapped value.
+    fn try_borrow(&self) -> Result<UserDataRef<T>> {
+        self.0
+            .try_borrow()
+            .map(|r| UserDataRef(UserDataRefInner::Ref(r)))
+            .map_err(|_| Error::UserDataBorrowError)
+    }
+
+    // Mutably borrows the wrapped value.
+    fn try_borrow_mut(&self) -> Result<UserDataRefMut<T>> {
+        self.0
+            .try_borrow_mut()
+            .map(|r| UserDataRefMut(UserDataRefMutInner::Ref(r)))
+            .map_err(|_| Error::UserDataBorrowMutError)
     }
 }
 
-impl<T> Deref for UserDataCell<T> {
-    type Target = RefCell<UserDataWrapped<T>>;
+#[cfg(feature = "serialize")]
+impl Serialize for UserDataCell<()> {
+    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let ser = self
+            .0
+            .try_borrow()
+            .map_err(|_| ser::Error::custom(Error::UserDataBorrowError))?
+            .ser;
+        unsafe { (&*ser).serialize(serializer) }
+    }
+}
+
+/// A wrapper type for an immutably borrowed value from an `AnyUserData`.
+pub struct UserDataRef<'a, T>(UserDataRefInner<'a, T>);
+
+enum UserDataRefInner<'a, T> {
+    Ref(Ref<'a, UserDataWrapped<T>>),
+}
+
+/// A wrapper type for a mutably borrowed value from an `AnyUserData`.
+pub struct UserDataRefMut<'a, T>(UserDataRefMutInner<'a, T>);
+
+enum UserDataRefMutInner<'a, T> {
+    Ref(RefMut<'a, UserDataWrapped<T>>),
+}
+
+impl<T> Deref for UserDataRef<'_, T> {
+    type Target = T;
 
     fn deref(&self) -> &Self::Target {
-        match self {
-            UserDataCell::Arc(t) => &*t,
-            UserDataCell::Plain(t) => &*t,
+        match &self.0 {
+            UserDataRefInner::Ref(x) => &*x,
         }
     }
 }
 
-impl<T> Clone for UserDataCell<T> {
-    fn clone(&self) -> Self {
-        match self {
-            UserDataCell::Arc(t) => UserDataCell::Arc(t.clone()),
-            UserDataCell::Plain(_) => mlua_panic!("cannot clone non-arc userdata"),
+impl<T> Deref for UserDataRefMut<'_, T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        match &self.0 {
+            UserDataRefMutInner::Ref(x) => &*x,
         }
     }
 }
 
+impl<T> DerefMut for UserDataRefMut<'_, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        match &mut self.0 {
+            UserDataRefMutInner::Ref(x) => &mut *x,
+        }
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for UserDataRef<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&*self as &T, f)
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for UserDataRefMut<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&*self as &T, f)
+    }
+}
+
+impl<T: fmt::Display> fmt::Display for UserDataRef<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&*self as &T, f)
+    }
+}
+
+impl<T: fmt::Display> fmt::Display for UserDataRefMut<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&*self as &T, f)
+    }
+}
+
 pub(crate) struct UserDataWrapped<T> {
     pub(crate) data: *mut T,
     #[cfg(feature = "serialize")]
     ser: *mut dyn erased_serde::Serialize,
 }
 
+impl<T> UserDataWrapped<T> {
+    fn new(data: T) -> Self {
+        UserDataWrapped {
+            data: Box::into_raw(Box::new(data)),
+            #[cfg(feature = "serialize")]
+            ser: Box::into_raw(Box::new(UserDataSerializeError)),
+        }
+    }
+
+    #[cfg(feature = "serialize")]
+    fn new_ser(data: T) -> Self
+    where
+        T: 'static + Serialize,
+    {
+        let data_raw = Box::into_raw(Box::new(data));
+        UserDataWrapped {
+            data: data_raw,
+            ser: data_raw,
+        }
+    }
+}
+
 impl<T> Drop for UserDataWrapped<T> {
     fn drop(&mut self) {
         unsafe {
@@ -623,20 +744,22 @@ impl<T> Drop for UserDataWrapped<T> {
     }
 }
 
-impl<T> AsRef<T> for UserDataWrapped<T> {
-    fn as_ref(&self) -> &T {
+impl<T> Deref for UserDataWrapped<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
         unsafe { &*self.data }
     }
 }
 
-impl<T> AsMut<T> for UserDataWrapped<T> {
-    fn as_mut(&mut self) -> &mut T {
+impl<T> DerefMut for UserDataWrapped<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
         unsafe { &mut *self.data }
     }
 }
 
 #[cfg(feature = "serialize")]
-pub(crate) struct UserDataSerializeError;
+struct UserDataSerializeError;
 
 #[cfg(feature = "serialize")]
 impl Serialize for UserDataSerializeError {
@@ -683,26 +806,18 @@ impl<'lua> AnyUserData<'lua> {
     ///
     /// Returns a `UserDataBorrowError` if the userdata is already mutably borrowed. Returns a
     /// `UserDataTypeMismatch` if the userdata is not of type `T`.
-    pub fn borrow<T: 'static + UserData>(&self) -> Result<Ref<T>> {
-        self.inspect(|cell| {
-            let cell_ref = cell.try_borrow().map_err(|_| Error::UserDataBorrowError)?;
-            Ok(Ref::map(cell_ref, |x| unsafe { &*x.data }))
-        })
+    pub fn borrow<T: 'static + UserData>(&self) -> Result<UserDataRef<T>> {
+        self.inspect(|cell| cell.try_borrow())
     }
 
     /// Borrow this userdata mutably if it is of type `T`.
     ///
     /// # Errors
     ///
-    /// Returns a `UserDataBorrowMutError` if the userdata is already borrowed. Returns a
-    /// `UserDataTypeMismatch` if the userdata is not of type `T`.
-    pub fn borrow_mut<T: 'static + UserData>(&self) -> Result<RefMut<T>> {
-        self.inspect(|cell| {
-            let cell_ref = cell
-                .try_borrow_mut()
-                .map_err(|_| Error::UserDataBorrowMutError)?;
-            Ok(RefMut::map(cell_ref, |x| unsafe { &mut *x.data }))
-        })
+    /// Returns a `UserDataBorrowMutError` if the userdata cannot be mutably borrowed.
+    /// Returns a `UserDataTypeMismatch` if the userdata is not of type `T`.
+    pub fn borrow_mut<T: 'static + UserData>(&self) -> Result<UserDataRefMut<T>> {
+        self.inspect(|cell| cell.try_borrow_mut())
     }
 
     /// Sets an associated value to this `AnyUserData`.
@@ -726,7 +841,7 @@ impl<'lua> AnyUserData<'lua> {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, 3)?;
 
-            lua.push_userdata_ref(&self.0)?;
+            lua.push_userdata_ref(&self.0, false)?;
             lua.push_value(v)?;
             ffi::lua_setuservalue(lua.state, -2);
 
@@ -745,7 +860,7 @@ impl<'lua> AnyUserData<'lua> {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, 3)?;
 
-            lua.push_userdata_ref(&self.0)?;
+            lua.push_userdata_ref(&self.0, false)?;
             ffi::lua_getuservalue(lua.state, -1);
             lua.pop_value()
         };
@@ -776,7 +891,7 @@ impl<'lua> AnyUserData<'lua> {
             let _sg = StackGuard::new(lua.state);
             check_stack(lua.state, 3)?;
 
-            lua.push_userdata_ref(&self.0)?;
+            lua.push_userdata_ref(&self.0, false)?;
             ffi::lua_getmetatable(lua.state, -1); // Checked that non-empty on the previous call
             Ok(Table(lua.pop_ref()))
         }
@@ -803,6 +918,25 @@ impl<'lua> AnyUserData<'lua> {
         Ok(false)
     }
 
+    pub(crate) fn type_id(&self) -> Result<TypeId> {
+        let lua = self.0.lua;
+        unsafe {
+            let _sg = StackGuard::new(lua.state);
+            check_stack(lua.state, 5)?;
+
+            // Push userdata with metatable
+            lua.push_userdata_ref(&self.0, true)?;
+
+            // Get the special `__mlua_type_id`
+            push_string(lua.state, "__mlua_type_id")?;
+            if ffi::lua_rawget(lua.state, -2) != ffi::LUA_TUSERDATA {
+                return Err(Error::UserDataTypeMismatch);
+            }
+
+            Ok(*(ffi::lua_touserdata(lua.state, -1) as *const TypeId))
+        }
+    }
+
     fn inspect<'a, T, R, F>(&'a self, func: F) -> Result<R>
     where
         T: 'static + UserData,
@@ -928,17 +1062,15 @@ impl<'lua> Serialize for AnyUserData<'lua> {
     where
         S: Serializer,
     {
-        let res = (|| unsafe {
+        unsafe {
             let lua = self.0.lua;
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 3)?;
+            check_stack(lua.state, 3).map_err(ser::Error::custom)?;
 
-            lua.push_userdata_ref(&self.0)?;
+            lua.push_userdata_ref(&self.0, false)
+                .map_err(ser::Error::custom)?;
             let ud = &*get_userdata::<UserDataCell<()>>(lua.state, -1);
-            (*ud.try_borrow().map_err(|_| Error::UserDataBorrowError)?.ser)
-                .serialize(serializer)
-                .map_err(|err| Error::SerializeError(err.to_string()))
-        })();
-        res.map_err(ser::Error::custom)
+            ud.serialize(serializer)
+        }
     }
 }

src/util.rs

@@ -2,7 +2,7 @@ use std::any::{Any, TypeId};
 use std::collections::HashMap;
 use std::error::Error as StdError;
 use std::fmt::Write;
-use std::os::raw::{c_int, c_void};
+use std::os::raw::{c_char, c_int, c_void};
 use std::panic::{catch_unwind, resume_unwind, AssertUnwindSafe};
 use std::sync::{Arc, Mutex};
 use std::{mem, ptr, slice};
@@ -85,27 +85,71 @@ impl Drop for StackGuard {
 
 // Call a function that calls into the Lua API and may trigger a Lua error (longjmp) in a safe way.
 // Wraps the inner function in a call to `lua_pcall`, so the inner function only has access to a
-// limited lua stack. `nargs` is the same as the the parameter to `lua_pcall`, and `nresults` is
-// always LUA_MULTRET. Internally uses 2 extra stack spaces, and does not call checkstack.
-// Provided function must *never* panic.
-pub unsafe fn protect_lua(
+// limited lua stack. `nargs` and `nresults` are similar to the parameters of `lua_pcall`, but the
+// given function return type is not the return value count, instead the inner function return
+// values are assumed to match the `nresults` param. Provided function must *not* panic, and since it
+// will generally be lonjmping, should not contain any values that implements Drop.
+// Internally uses 3 extra stack spaces, and does not call checkstack.
+pub unsafe fn protect_lua<F, R>(
     state: *mut ffi::lua_State,
     nargs: c_int,
-    f: unsafe extern "C" fn(*mut ffi::lua_State) -> c_int, // Must be "C-unwind" after stabilizing
-) -> Result<()> {
+    nresults: c_int,
+    f: F,
+) -> Result<R>
+where
+    F: Fn(*mut ffi::lua_State) -> R,
+    R: Copy,
+{
+    union URes<R: Copy> {
+        uninit: (),
+        init: R,
+    }
+
+    struct Params<F, R: Copy> {
+        function: F,
+        result: URes<R>,
+        nresults: c_int,
+    }
+
+    unsafe extern "C" fn do_call<F, R>(state: *mut ffi::lua_State) -> c_int
+    where
+        R: Copy,
+        F: Fn(*mut ffi::lua_State) -> R,
+    {
+        let params = ffi::lua_touserdata(state, -1) as *mut Params<F, R>;
+        ffi::lua_pop(state, 1);
+
+        (*params).result.init = ((*params).function)(state);
+
+        if (*params).nresults == ffi::LUA_MULTRET {
+            ffi::lua_gettop(state)
+        } else {
+            (*params).nresults
+        }
+    }
+
     let stack_start = ffi::lua_gettop(state) - nargs;
 
-    ffi::lua_pushcfunction(state, ffi::safe::error_traceback);
-    ffi::lua_pushcfunction(state, f);
+    ffi::lua_pushcfunction(state, error_traceback);
+    ffi::lua_pushcfunction(state, do_call::<F, R>);
     if nargs > 0 {
         ffi::lua_rotate(state, stack_start + 1, 2);
     }
 
-    let ret = ffi::lua_pcall(state, nargs, ffi::LUA_MULTRET, stack_start + 1);
+    let mut params = Params {
+        function: f,
+        result: URes { uninit: () },
+        nresults,
+    };
+
+    ffi::lua_pushlightuserdata(state, &mut params as *mut Params<F, R> as *mut c_void);
+    let ret = ffi::lua_pcall(state, nargs + 1, nresults, stack_start + 1);
     ffi::lua_remove(state, stack_start + 1);
 
     if ret == ffi::LUA_OK {
-        Ok(())
+        // `LUA_OK` is only returned when the `do_call` function has completed successfully, so
+        // `params.result` is definitely initialized.
+        Ok(params.result.init)
     } else {
         Err(pop_error(state, ret))
     }
@@ -162,9 +206,41 @@ pub unsafe fn pop_error(state: *mut ffi::lua_State, err_code: c_int) -> Error {
     }
 }
 
+// Uses 3 stack spaces
+pub unsafe fn push_string<S: AsRef<[u8]> + ?Sized>(
+    state: *mut ffi::lua_State,
+    s: &S,
+) -> Result<()> {
+    let s = s.as_ref();
+    protect_lua(state, 0, 1, |state| {
+        ffi::lua_pushlstring(state, s.as_ptr() as *const c_char, s.len());
+    })
+}
+
+// Uses 3 stack spaces
+pub unsafe fn push_table(state: *mut ffi::lua_State, narr: c_int, nrec: c_int) -> Result<()> {
+    protect_lua(state, 0, 1, |state| ffi::lua_createtable(state, narr, nrec))
+}
+
+// Uses 4 stack spaces
+pub unsafe fn rawset_field<S>(state: *mut ffi::lua_State, table: c_int, field: &S) -> Result<()>
+where
+    S: AsRef<[u8]> + ?Sized,
+{
+    let field = field.as_ref();
+    ffi::lua_pushvalue(state, table);
+    protect_lua(state, 2, 0, |state| {
+        ffi::lua_pushlstring(state, field.as_ptr() as *const c_char, field.len());
+        ffi::lua_rotate(state, -3, 2);
+        ffi::lua_rawset(state, -3)
+    })
+}
+
 // Internally uses 3 stack spaces, does not call checkstack.
 pub unsafe fn push_userdata<T>(state: *mut ffi::lua_State, t: T) -> Result<()> {
-    let ud = ffi::safe::lua_newuserdata(state, mem::size_of::<T>())? as *mut T;
+    let ud = protect_lua(state, 0, 1, |state| {
+        ffi::lua_newuserdata(state, mem::size_of::<T>()) as *mut T
+    })?;
     ptr::write(ud, t);
     Ok(())
 }
@@ -230,13 +306,99 @@ pub unsafe fn init_userdata_metatable<T>(
     field_setters: Option<c_int>,
     methods: Option<c_int>,
 ) -> Result<()> {
+    // Wrapper to lookup in `field_getters` first, then `methods`, ending original `__index`.
+    // Used only if `field_getters` or `methods` set.
+    unsafe extern "C" fn meta_index_impl(state: *mut ffi::lua_State) -> c_int {
+        // stack: self, key
+        ffi::luaL_checkstack(state, 2, ptr::null());
+
+        // lookup in `field_getters` table
+        if ffi::lua_isnil(state, ffi::lua_upvalueindex(2)) == 0 {
+            ffi::lua_pushvalue(state, -1); // `key` arg
+            if ffi::lua_rawget(state, ffi::lua_upvalueindex(2)) != ffi::LUA_TNIL {
+                ffi::lua_insert(state, -3); // move function
+                ffi::lua_pop(state, 1); // remove `key`
+                ffi::lua_call(state, 1, 1);
+                return 1;
+            }
+            ffi::lua_pop(state, 1); // pop the nil value
+        }
+        // lookup in `methods` table
+        if ffi::lua_isnil(state, ffi::lua_upvalueindex(3)) == 0 {
+            ffi::lua_pushvalue(state, -1); // `key` arg
+            if ffi::lua_rawget(state, ffi::lua_upvalueindex(3)) != ffi::LUA_TNIL {
+                ffi::lua_insert(state, -3);
+                ffi::lua_pop(state, 2);
+                return 1;
+            }
+            ffi::lua_pop(state, 1); // pop the nil value
+        }
+
+        // lookup in `__index`
+        ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
+        match ffi::lua_type(state, -1) {
+            ffi::LUA_TNIL => {
+                ffi::lua_pop(state, 1); // pop the nil value
+                let field = ffi::lua_tostring(state, -1);
+                ffi::luaL_error(state, cstr!("attempt to get an unknown field '%s'"), field);
+            }
+            ffi::LUA_TTABLE => {
+                ffi::lua_insert(state, -2);
+                ffi::lua_gettable(state, -2);
+            }
+            ffi::LUA_TFUNCTION => {
+                ffi::lua_insert(state, -3);
+                ffi::lua_call(state, 2, 1);
+            }
+            _ => unreachable!(),
+        }
+
+        1
+    }
+
+    // Similar to `meta_index_impl`, checks `field_setters` table first, then `__newindex` metamethod.
+    // Used only if `field_setters` set.
+    unsafe extern "C" fn meta_newindex_impl(state: *mut ffi::lua_State) -> c_int {
+        // stack: self, key, value
+        ffi::luaL_checkstack(state, 2, ptr::null());
+
+        // lookup in `field_setters` table
+        ffi::lua_pushvalue(state, -2); // `key` arg
+        if ffi::lua_rawget(state, ffi::lua_upvalueindex(2)) != ffi::LUA_TNIL {
+            ffi::lua_remove(state, -3); // remove `key`
+            ffi::lua_insert(state, -3); // move function
+            ffi::lua_call(state, 2, 0);
+            return 0;
+        }
+        ffi::lua_pop(state, 1); // pop the nil value
+
+        // lookup in `__newindex`
+        ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
+        match ffi::lua_type(state, -1) {
+            ffi::LUA_TNIL => {
+                ffi::lua_pop(state, 1); // pop the nil value
+                let field = ffi::lua_tostring(state, -2);
+                ffi::luaL_error(state, cstr!("attempt to set an unknown field '%s'"), field);
+            }
+            ffi::LUA_TTABLE => {
+                ffi::lua_insert(state, -3);
+                ffi::lua_settable(state, -3);
+            }
+            ffi::LUA_TFUNCTION => {
+                ffi::lua_insert(state, -4);
+                ffi::lua_call(state, 3, 0);
+            }
+            _ => unreachable!(),
+        }
+
+        0
+    }
+
     ffi::lua_pushvalue(state, metatable);
 
     if field_getters.is_some() || methods.is_some() {
-        ffi::safe::lua_pushstring(state, "__index")?;
-
-        ffi::lua_pushvalue(state, -1);
-        let index_type = ffi::lua_rawget(state, -3);
+        push_string(state, "__index")?;
+        let index_type = ffi::lua_rawget(state, -2);
         match index_type {
             ffi::LUA_TNIL | ffi::LUA_TTABLE | ffi::LUA_TFUNCTION => {
                 for &idx in &[field_getters, methods] {
@@ -246,35 +408,37 @@ pub unsafe fn init_userdata_metatable<T>(
                         ffi::lua_pushnil(state);
                     }
                 }
-                ffi::safe::lua_pushcclosure(state, ffi::safe::meta_index_impl, 3)?;
+                protect_lua(state, 3, 1, |state| {
+                    ffi::lua_pushcclosure(state, meta_index_impl, 3)
+                })?;
             }
             _ => mlua_panic!("improper __index type {}", index_type),
         }
 
-        ffi::safe::lua_rawset(state, -3)?;
+        rawset_field(state, -2, "__index")?;
     }
 
     if let Some(field_setters) = field_setters {
-        ffi::safe::lua_pushstring(state, "__newindex")?;
-
-        ffi::lua_pushvalue(state, -1);
-        let newindex_type = ffi::lua_rawget(state, -3);
+        push_string(state, "__newindex")?;
+        let newindex_type = ffi::lua_rawget(state, -2);
         match newindex_type {
             ffi::LUA_TNIL | ffi::LUA_TTABLE | ffi::LUA_TFUNCTION => {
                 ffi::lua_pushvalue(state, field_setters);
-                ffi::safe::lua_pushcclosure(state, ffi::safe::meta_newindex_impl, 2)?;
+                protect_lua(state, 2, 1, |state| {
+                    ffi::lua_pushcclosure(state, meta_newindex_impl, 2)
+                })?;
             }
             _ => mlua_panic!("improper __newindex type {}", newindex_type),
         }
 
-        ffi::safe::lua_rawset(state, -3)?;
+        rawset_field(state, -2, "__newindex")?;
     }
 
-    ffi::safe::lua_pushrclosure(state, userdata_destructor::<T>, 0)?;
-    ffi::safe::lua_rawsetfield(state, -2, "__gc")?;
+    ffi::lua_pushcfunction(state, userdata_destructor::<T>);
+    rawset_field(state, -2, "__gc")?;
 
     ffi::lua_pushboolean(state, 0);
-    ffi::safe::lua_rawsetfield(state, -2, "__metatable")?;
+    rawset_field(state, -2, "__metatable")?;
 
     ffi::lua_pop(state, 1);
 
@@ -290,21 +454,38 @@ pub unsafe extern "C" fn userdata_destructor<T>(state: *mut ffi::lua_State) -> c
 }
 
 // In the context of a lua callback, this will call the given function and if the given function
-// returns an error, *or if the given function panics*, this will result in a call to lua_error (a
-// longjmp) by a C shim. The error or panic is wrapped in such a way that when calling pop_error back
-// on the rust side, it will resume the panic (or when popping a panic value from the stack).
+// returns an error, *or if the given function panics*, this will result in a call to `lua_error` (a
+// longjmp). The error or panic is wrapped in such a way that when calling `pop_error` back on
+// the Rust side, it will resume the panic.
 //
 // This function assumes the structure of the stack at the beginning of a callback, that the only
 // elements on the stack are the arguments to the callback.
 //
 // This function uses some of the bottom of the stack for error handling, the given callback will be
 // given the number of arguments available as an argument, and should return the number of returns
-// as normal, but cannot assume that the arguments available start at 1.
-pub unsafe fn callback_error<F>(state: *mut ffi::lua_State, f: F) -> c_int
+// as normal, but cannot assume that the arguments available start at 0.
+pub unsafe fn callback_error<F, R>(state: *mut ffi::lua_State, f: F) -> R
 where
-    F: FnOnce(c_int) -> Result<c_int>,
+    F: FnOnce(c_int) -> Result<R>,
 {
-    let nargs = ffi::lua_gettop(state) - 1;
+    let nargs = ffi::lua_gettop(state);
+
+    // We need 2 extra stack spaces to store preallocated memory and error/panic metatable
+    let extra_stack = if nargs < 2 { 2 - nargs } else { 1 };
+    ffi::luaL_checkstack(
+        state,
+        extra_stack,
+        cstr!("not enough stack space for callback error handling"),
+    );
+
+    // We cannot shadow Rust errors with Lua ones, we pre-allocate enough memory
+    // to store a wrapped error or panic *before* we proceed.
+    let ud = ffi::lua_newuserdata(
+        state,
+        mem::size_of::<WrappedError>().max(mem::size_of::<WrappedPanic>()),
+    );
+    ffi::lua_rotate(state, 1, 1);
+
     match catch_unwind(AssertUnwindSafe(|| f(nargs))) {
         Ok(Ok(r)) => {
             ffi::lua_remove(state, 1);
@@ -312,42 +493,120 @@ where
         }
         Ok(Err(err)) => {
             ffi::lua_settop(state, 1);
-            let error_ud = ffi::lua_touserdata(state, 1);
-            ptr::write(error_ud as *mut WrappedError, WrappedError(err));
+
+            let wrapped_error = ud as *mut WrappedError;
+            ptr::write(wrapped_error, WrappedError(err));
             get_gc_metatable_for::<WrappedError>(state);
             ffi::lua_setmetatable(state, -2);
-            -1
+
+            // Convert to CallbackError and attach traceback
+            let traceback = if ffi::lua_checkstack(state, ffi::LUA_TRACEBACK_STACK) != 0 {
+                ffi::luaL_traceback(state, state, ptr::null(), 0);
+                let traceback = to_string(state, -1);
+                ffi::lua_pop(state, 1);
+                traceback
+            } else {
+                "<not enough stack space for traceback>".to_string()
+            };
+            let cause = Arc::new((*wrapped_error).0.clone());
+            (*wrapped_error).0 = Error::CallbackError { traceback, cause };
+
+            ffi::lua_error(state)
         }
         Err(p) => {
             ffi::lua_settop(state, 1);
-            let error_ud = ffi::lua_touserdata(state, 1);
-            ptr::write(error_ud as *mut WrappedPanic, WrappedPanic(Some(p)));
+            ptr::write(ud as *mut WrappedPanic, WrappedPanic(Some(p)));
             get_gc_metatable_for::<WrappedPanic>(state);
             ffi::lua_setmetatable(state, -2);
-            -2
+            ffi::lua_error(state)
         }
     }
 }
 
-// A part of the C shim for errors handling.
-// Receives indexes of error and traceback (optional) in the stack.
-// Converts error into a `CallbackError` and attaches the traceback provided.
-#[no_mangle]
-pub unsafe extern "C" fn wrapped_error_traceback(
-    state: *mut ffi::lua_State,
-    error_idx: c_int,
-    traceback_idx: c_int,
-) {
-    let wrapped_error = mlua_expect!(
-        get_gc_userdata::<WrappedError>(state, error_idx).as_mut(),
-        "cannot get <WrappedError>"
-    );
-    let traceback = match traceback_idx {
-        0 => "<not enough stack space for traceback>".to_string(),
-        _ => to_string(state, traceback_idx),
-    };
-    let cause = Arc::new(wrapped_error.0.clone());
-    wrapped_error.0 = Error::CallbackError { traceback, cause };
+pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
+    if ffi::lua_checkstack(state, 2) == 0 {
+        // If we don't have enough stack space to even check the error type, do
+        // nothing so we don't risk shadowing a rust panic.
+        return 1;
+    }
+
+    if get_gc_userdata::<WrappedError>(state, -1).is_null()
+        && get_gc_userdata::<WrappedPanic>(state, -1).is_null()
+    {
+        let s = ffi::luaL_tolstring(state, -1, ptr::null_mut());
+        if ffi::lua_checkstack(state, ffi::LUA_TRACEBACK_STACK) != 0 {
+            ffi::luaL_traceback(state, state, s, 1);
+            ffi::lua_remove(state, -2);
+        }
+    }
+
+    1
+}
+
+// A variant of `pcall` that does not allow Lua to catch Rust panics from `callback_error`.
+pub unsafe extern "C" fn safe_pcall(state: *mut ffi::lua_State) -> c_int {
+    ffi::luaL_checkstack(state, 2, ptr::null());
+
+    let top = ffi::lua_gettop(state);
+    if top == 0 {
+        ffi::lua_pushstring(state, cstr!("not enough arguments to pcall"));
+        ffi::lua_error(state);
+    }
+
+    if ffi::lua_pcall(state, top - 1, ffi::LUA_MULTRET, 0) == ffi::LUA_OK {
+        ffi::lua_pushboolean(state, 1);
+        ffi::lua_insert(state, 1);
+        ffi::lua_gettop(state)
+    } else {
+        if !get_gc_userdata::<WrappedPanic>(state, -1).is_null() {
+            ffi::lua_error(state);
+        }
+        ffi::lua_pushboolean(state, 0);
+        ffi::lua_insert(state, -2);
+        2
+    }
+}
+
+// A variant of `xpcall` that does not allow Lua to catch Rust panics from `callback_error`.
+pub unsafe extern "C" fn safe_xpcall(state: *mut ffi::lua_State) -> c_int {
+    unsafe extern "C" fn xpcall_msgh(state: *mut ffi::lua_State) -> c_int {
+        ffi::luaL_checkstack(state, 2, ptr::null());
+
+        if !get_gc_userdata::<WrappedPanic>(state, -1).is_null() {
+            1
+        } else {
+            ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
+            ffi::lua_insert(state, 1);
+            ffi::lua_call(state, ffi::lua_gettop(state) - 1, ffi::LUA_MULTRET);
+            ffi::lua_gettop(state)
+        }
+    }
+
+    ffi::luaL_checkstack(state, 2, ptr::null());
+
+    let top = ffi::lua_gettop(state);
+    if top < 2 {
+        ffi::lua_pushstring(state, cstr!("not enough arguments to xpcall"));
+        ffi::lua_error(state);
+    }
+
+    ffi::lua_pushvalue(state, 2);
+    ffi::lua_pushcclosure(state, xpcall_msgh, 1);
+    ffi::lua_copy(state, 1, 2);
+    ffi::lua_replace(state, 1);
+
+    if ffi::lua_pcall(state, ffi::lua_gettop(state) - 2, ffi::LUA_MULTRET, 1) == ffi::LUA_OK {
+        ffi::lua_pushboolean(state, 1);
+        ffi::lua_insert(state, 2);
+        ffi::lua_gettop(state) - 1
+    } else {
+        if !get_gc_userdata::<WrappedPanic>(state, -1).is_null() {
+            ffi::lua_error(state);
+        }
+        ffi::lua_pushboolean(state, 0);
+        ffi::lua_insert(state, -2);
+        2
+    }
 }
 
 // Returns Lua main thread for Lua >= 5.2 or checks that the passed thread is main for Lua 5.1.
@@ -374,13 +633,9 @@ pub unsafe fn get_main_state(state: *mut ffi::lua_State) -> Option<*mut ffi::lua
 }
 
 // Pushes a WrappedError to the top of the stack.
-// Uses 2 stack spaces and does not call checkstack.
+// Uses 3 stack spaces and does not call checkstack.
 pub unsafe fn push_wrapped_error(state: *mut ffi::lua_State, err: Error) -> Result<()> {
-    let error_ud = ffi::safe::lua_newwrappederror(state)? as *mut WrappedError;
-    ptr::write(error_ud, WrappedError(err));
-    get_gc_metatable_for::<WrappedError>(state);
-    ffi::lua_setmetatable(state, -2);
-    Ok(())
+    push_gc_userdata::<WrappedError>(state, WrappedError(err))
 }
 
 // Checks if the value at the given index is a WrappedError, and if it is returns a pointer to it,
@@ -399,7 +654,7 @@ pub unsafe fn get_wrapped_error(state: *mut ffi::lua_State, index: c_int) -> *co
 pub unsafe fn init_gc_metatable_for<T: Any>(
     state: *mut ffi::lua_State,
     customize_fn: Option<fn(*mut ffi::lua_State) -> Result<()>>,
-) -> Result<*const u8> {
+) -> Result<()> {
     check_stack(state, 6)?;
 
     let type_id = TypeId::of::<T>();
@@ -413,21 +668,23 @@ pub unsafe fn init_gc_metatable_for<T: Any>(
         &mt_cache[&type_id] as *const u8
     };
 
-    ffi::safe::lua_createtable(state, 0, 3)?;
+    push_table(state, 0, 3)?;
 
-    ffi::safe::lua_pushrclosure(state, userdata_destructor::<T>, 0)?;
-    ffi::safe::lua_rawsetfield(state, -2, "__gc")?;
+    ffi::lua_pushcfunction(state, userdata_destructor::<T>);
+    rawset_field(state, -2, "__gc")?;
 
     ffi::lua_pushboolean(state, 0);
-    ffi::safe::lua_rawsetfield(state, -2, "__metatable")?;
+    rawset_field(state, -2, "__metatable")?;
 
     if let Some(f) = customize_fn {
         f(state)?;
     }
 
-    ffi::safe::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, ref_addr as *mut c_void)?;
+    protect_lua(state, 1, 0, |state| {
+        ffi::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, ref_addr as *mut c_void)
+    })?;
 
-    Ok(ref_addr)
+    Ok(())
 }
 
 pub unsafe fn get_gc_metatable_for<T: Any>(state: *mut ffi::lua_State) {
@@ -441,7 +698,7 @@ pub unsafe fn get_gc_metatable_for<T: Any>(state: *mut ffi::lua_State) {
 
 // Initialize the error, panic, and destructed userdata metatables.
 // Returns address of WrappedError and WrappedPanic metatables in Lua registry.
-pub unsafe fn init_error_registry(state: *mut ffi::lua_State) -> Result<(*const u8, *const u8)> {
+pub unsafe fn init_error_registry(state: *mut ffi::lua_State) -> Result<()> {
     check_stack(state, 7)?;
 
     // Create error and panic metatables
@@ -509,44 +766,37 @@ pub unsafe fn init_error_registry(state: *mut ffi::lua_State) -> Result<(*const
                 Err(Error::UserDataTypeMismatch)
             }?;
 
-            ffi::safe::lua_pushstring(state, &*err_buf)?;
+            push_string(state, &*err_buf)?;
             (*err_buf).clear();
 
             Ok(1)
         })
     }
 
-    let wrapped_error_key = init_gc_metatable_for::<WrappedError>(
+    init_gc_metatable_for::<WrappedError>(
         state,
         Some(|state| {
-            ffi::safe::lua_pushrclosure(state, error_tostring, 0)?;
-            ffi::safe::lua_rawsetfield(state, -2, "__tostring")
+            ffi::lua_pushcfunction(state, error_tostring);
+            rawset_field(state, -2, "__tostring")
         }),
     )?;
 
-    let wrapped_panic_key = init_gc_metatable_for::<WrappedPanic>(
+    init_gc_metatable_for::<WrappedPanic>(
         state,
         Some(|state| {
-            ffi::safe::lua_pushrclosure(state, error_tostring, 0)?;
-            ffi::safe::lua_rawsetfield(state, -2, "__tostring")
+            ffi::lua_pushcfunction(state, error_tostring);
+            rawset_field(state, -2, "__tostring")
         }),
     )?;
 
     // Create destructed userdata metatable
 
     unsafe extern "C" fn destructed_error(state: *mut ffi::lua_State) -> c_int {
-        callback_error(state, |_| {
-            check_stack(state, 2)?;
-            let error_ud = ffi::safe::lua_newwrappederror(state)? as *mut WrappedError;
-            ptr::write(error_ud, WrappedError(Error::CallbackDestructed));
-            get_gc_metatable_for::<WrappedError>(state);
-            ffi::lua_setmetatable(state, -2);
-            Ok(-1) // to trigger lua_error
-        })
+        callback_error(state, |_| Err(Error::CallbackDestructed))
     }
 
-    ffi::safe::lua_createtable(state, 0, 26)?;
-    ffi::safe::lua_pushrclosure(state, destructed_error, 0)?;
+    push_table(state, 0, 26)?;
+    ffi::lua_pushcfunction(state, destructed_error);
     for &method in &[
         "__add",
         "__sub",
@@ -586,20 +836,24 @@ pub unsafe fn init_error_registry(state: *mut ffi::lua_State) -> Result<(*const
         "__close",
     ] {
         ffi::lua_pushvalue(state, -1);
-        ffi::safe::lua_rawsetfield(state, -3, method)?;
+        rawset_field(state, -3, method)?;
     }
     ffi::lua_pop(state, 1);
 
     let destructed_metatable_key = &DESTRUCTED_USERDATA_METATABLE as *const u8 as *const c_void;
-    ffi::safe::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, destructed_metatable_key)?;
+    protect_lua(state, 1, 0, |state| {
+        ffi::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, destructed_metatable_key)
+    })?;
 
     // Create error print buffer
     init_gc_metatable_for::<String>(state, None)?;
     push_gc_userdata(state, String::new())?;
     let err_buf_key = &ERROR_PRINT_BUFFER_KEY as *const u8 as *const c_void;
-    ffi::safe::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, err_buf_key)?;
+    protect_lua(state, 1, 0, |state| {
+        ffi::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, err_buf_key)
+    })?;
 
-    Ok((wrapped_error_key, wrapped_panic_key))
+    Ok(())
 }
 
 pub(crate) struct WrappedError(pub Error);
@@ -607,7 +861,7 @@ pub(crate) struct WrappedPanic(pub Option<Box<dyn Any + Send + 'static>>);
 
 // Converts the given lua value to a string in a reasonable format without causing a Lua error or
 // panicking.
-unsafe fn to_string(state: *mut ffi::lua_State, index: c_int) -> String {
+pub(crate) unsafe fn to_string(state: *mut ffi::lua_State, index: c_int) -> String {
     match ffi::lua_type(state, index) {
         ffi::LUA_TNONE => "<none>".to_string(),
         ffi::LUA_TNIL => "<nil>".to_string(),

tests/byte_string.rs

@@ -2,7 +2,7 @@ use bstr::{BStr, BString};
 use mlua::{Lua, Result};
 
 #[test]
-fn byte_string_round_trip() -> Result<()> {
+fn test_byte_string_round_trip() -> Result<()> {
     let lua = Lua::new();
 
     lua.load(

tests/conversion.rs

@@ -1,6 +1,6 @@
 use std::borrow::Cow;
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
-use std::ffi::CString;
+use std::ffi::{CStr, CString};
 
 use maplit::{btreemap, btreeset, hashmap, hashset};
 use mlua::{Lua, Result};
@@ -12,7 +12,7 @@ fn test_conv_vec() -> Result<()> {
     let v = vec![1, 2, 3];
     lua.globals().set("v", v.clone())?;
     let v2: Vec<i32> = lua.globals().get("v")?;
-    assert!(v == v2);
+    assert_eq!(v, v2);
 
     Ok(())
 }
@@ -24,7 +24,7 @@ fn test_conv_hashmap() -> Result<()> {
     let map = hashmap! {"hello".to_string() => "world".to_string()};
     lua.globals().set("map", map.clone())?;
     let map2: HashMap<String, String> = lua.globals().get("map")?;
-    assert!(map == map2);
+    assert_eq!(map, map2);
 
     Ok(())
 }
@@ -36,7 +36,10 @@ fn test_conv_hashset() -> Result<()> {
     let set = hashset! {"hello".to_string(), "world".to_string()};
     lua.globals().set("set", set.clone())?;
     let set2: HashSet<String> = lua.globals().get("set")?;
-    assert!(set == set2);
+    assert_eq!(set, set2);
+
+    let set3 = lua.load(r#"{"a", "b", "c"}"#).eval::<HashSet<String>>()?;
+    assert_eq!(set3, hashset! { "a".into(), "b".into(), "c".into() });
 
     Ok(())
 }
@@ -48,7 +51,7 @@ fn test_conv_btreemap() -> Result<()> {
     let map = btreemap! {"hello".to_string() => "world".to_string()};
     lua.globals().set("map", map.clone())?;
     let map2: BTreeMap<String, String> = lua.globals().get("map")?;
-    assert!(map == map2);
+    assert_eq!(map, map2);
 
     Ok(())
 }
@@ -60,7 +63,10 @@ fn test_conv_btreeset() -> Result<()> {
     let set = btreeset! {"hello".to_string(), "world".to_string()};
     lua.globals().set("set", set.clone())?;
     let set2: BTreeSet<String> = lua.globals().get("set")?;
-    assert!(set == set2);
+    assert_eq!(set, set2);
+
+    let set3 = lua.load(r#"{"a", "b", "c"}"#).eval::<BTreeSet<String>>()?;
+    assert_eq!(set3, btreeset! { "a".into(), "b".into(), "c".into() });
 
     Ok(())
 }
@@ -72,7 +78,12 @@ fn test_conv_cstring() -> Result<()> {
     let s = CString::new(b"hello".to_vec()).unwrap();
     lua.globals().set("s", s.clone())?;
     let s2: CString = lua.globals().get("s")?;
-    assert!(s == s2);
+    assert_eq!(s, s2);
+
+    let cs = CStr::from_bytes_with_nul(b"hello\0").unwrap();
+    lua.globals().set("cs", cs)?;
+    let cs2: CString = lua.globals().get("cs")?;
+    assert_eq!(cs, cs2.as_c_str());
 
     Ok(())
 }
@@ -84,7 +95,7 @@ fn test_conv_cow() -> Result<()> {
     let s = Cow::from("hello");
     lua.globals().set("s", s.clone())?;
     let s2: String = lua.globals().get("s")?;
-    assert!(s == s2);
+    assert_eq!(s, s2);
 
     Ok(())
 }
@@ -96,7 +107,7 @@ fn test_conv_boxed_str() -> Result<()> {
     let s = String::from("hello").into_boxed_str();
     lua.globals().set("s", s.clone())?;
     let s2: Box<str> = lua.globals().get("s")?;
-    assert!(s == s2);
+    assert_eq!(s, s2);
 
     Ok(())
 }
@@ -108,7 +119,7 @@ fn test_conv_boxed_slice() -> Result<()> {
     let v = vec![1, 2, 3].into_boxed_slice();
     lua.globals().set("v", v.clone())?;
     let v2: Box<[i32]> = lua.globals().get("v")?;
-    assert!(v == v2);
+    assert_eq!(v, v2);
 
     Ok(())
 }

tests/hooks.rs

@@ -6,7 +6,7 @@ use std::sync::{Arc, Mutex};
 use mlua::{Error, HookTriggers, Lua, Result, Value};
 
 #[test]
-fn line_counts() -> Result<()> {
+fn test_line_counts() -> Result<()> {
     let output = Arc::new(Mutex::new(Vec::new()));
     let hook_output = output.clone();
 
@@ -43,7 +43,7 @@ fn line_counts() -> Result<()> {
 }
 
 #[test]
-fn function_calls() -> Result<()> {
+fn test_function_calls() -> Result<()> {
     let output = Arc::new(Mutex::new(Vec::new()));
     let hook_output = output.clone();
 
@@ -95,7 +95,7 @@ fn function_calls() -> Result<()> {
 }
 
 #[test]
-fn error_within_hook() -> Result<()> {
+fn test_error_within_hook() -> Result<()> {
     let lua = Lua::new();
     lua.set_hook(
         HookTriggers {
@@ -126,7 +126,7 @@ fn error_within_hook() -> Result<()> {
 }
 
 #[test]
-fn limit_execution_instructions() -> Result<()> {
+fn test_limit_execution_instructions() -> Result<()> {
     let lua = Lua::new();
     let mut max_instructions = 10000;
 
@@ -165,7 +165,7 @@ fn limit_execution_instructions() -> Result<()> {
 }
 
 #[test]
-fn hook_removal() -> Result<()> {
+fn test_hook_removal() -> Result<()> {
     let lua = Lua::new();
 
     lua.set_hook(
@@ -188,7 +188,7 @@ fn hook_removal() -> Result<()> {
 }
 
 #[test]
-fn hook_swap_within_hook() -> Result<()> {
+fn test_hook_swap_within_hook() -> Result<()> {
     thread_local! {
         static TL_LUA: RefCell<Option<Lua>> = RefCell::new(None);
     }

tests/memory.rs

@@ -38,6 +38,9 @@ fn test_gc_control() -> Result<()> {
     let lua = Lua::new();
     let globals = lua.globals();
 
+    #[cfg(feature = "lua54")]
+    assert_eq!(lua.gc_gen(0, 0), mlua::GCMode::Incremental);
+
     #[cfg(any(feature = "lua54", feature = "lua53", feature = "lua52"))]
     {
         assert!(lua.gc_is_running());
@@ -59,6 +62,9 @@ fn test_gc_control() -> Result<()> {
     lua.gc_collect()?;
     assert_eq!(Arc::strong_count(&rc), 1);
 
+    #[cfg(feature = "lua54")]
+    assert_eq!(lua.gc_inc(0, 0, 0), mlua::GCMode::Generational);
+
     Ok(())
 }
 

tests/module/tests/load.rs

@@ -15,6 +15,32 @@ fn test_module() -> Result<()> {
     .exec()
 }
 
+#[test]
+fn test_module_multi() -> Result<()> {
+    let lua = make_lua()?;
+    lua.load(
+        r#"
+        local mod = require("rust_module")
+        local mod2 = require("rust_module.second")
+        assert(mod.check_userdata(mod2.userdata) == 123)
+    "#,
+    )
+    .exec()
+}
+
+#[test]
+fn test_module_error() -> Result<()> {
+    let lua = make_lua()?;
+    lua.load(
+        r#"
+        local ok, err = pcall(require, "rust_module.error")
+        assert(not ok)
+        assert(string.find(tostring(err), "custom module error"))
+    "#,
+    )
+    .exec()
+}
+
 #[cfg(any(
     feature = "lua54",
     feature = "lua53",

tests/scope.rs

@@ -8,7 +8,7 @@ use mlua::{
 };
 
 #[test]
-fn scope_func() -> Result<()> {
+fn test_scope_func() -> Result<()> {
     let lua = Lua::new();
 
     let rc = Rc::new(Cell::new(0));
@@ -38,7 +38,7 @@ fn scope_func() -> Result<()> {
 }
 
 #[test]
-fn scope_capture() -> Result<()> {
+fn test_scope_capture() -> Result<()> {
     let lua = Lua::new();
 
     let mut i = 0;
@@ -56,7 +56,7 @@ fn scope_capture() -> Result<()> {
 }
 
 #[test]
-fn scope_outer_lua_access() -> Result<()> {
+fn test_scope_outer_lua_access() -> Result<()> {
     let lua = Lua::new();
 
     let table = lua.create_table()?;
@@ -71,7 +71,7 @@ fn scope_outer_lua_access() -> Result<()> {
 }
 
 #[test]
-fn scope_userdata_fields() -> Result<()> {
+fn test_scope_userdata_fields() -> Result<()> {
     struct MyUserData<'a>(&'a Cell<i64>);
 
     impl<'a> UserData for MyUserData<'a> {
@@ -106,7 +106,7 @@ fn scope_userdata_fields() -> Result<()> {
 }
 
 #[test]
-fn scope_userdata_methods() -> Result<()> {
+fn test_scope_userdata_methods() -> Result<()> {
     struct MyUserData<'a>(&'a Cell<i64>);
 
     impl<'a> UserData for MyUserData<'a> {
@@ -147,7 +147,7 @@ fn scope_userdata_methods() -> Result<()> {
 }
 
 #[test]
-fn scope_userdata_functions() -> Result<()> {
+fn test_scope_userdata_functions() -> Result<()> {
     struct MyUserData<'a>(&'a i64);
 
     impl<'a> UserData for MyUserData<'a> {
@@ -189,7 +189,7 @@ fn scope_userdata_functions() -> Result<()> {
 }
 
 #[test]
-fn scope_userdata_mismatch() -> Result<()> {
+fn test_scope_userdata_mismatch() -> Result<()> {
     struct MyUserData<'a>(&'a Cell<i64>);
 
     impl<'a> UserData for MyUserData<'a> {
@@ -241,7 +241,7 @@ fn scope_userdata_mismatch() -> Result<()> {
 }
 
 #[test]
-fn scope_userdata_drop() -> Result<()> {
+fn test_scope_userdata_drop() -> Result<()> {
     let lua = Lua::new();
 
     struct MyUserData(Rc<()>);
@@ -299,7 +299,7 @@ fn scope_userdata_drop() -> Result<()> {
 }
 
 #[test]
-fn scope_nonstatic_userdata_drop() -> Result<()> {
+fn test_scope_nonstatic_userdata_drop() -> Result<()> {
     let lua = Lua::new();
 
     struct MyUserData<'a>(&'a Cell<i64>, Arc<()>);

tests/string.rs

@@ -3,7 +3,7 @@ use std::borrow::Cow;
 use mlua::{Lua, Result, String};
 
 #[test]
-fn compare() {
+fn test_string_compare() {
     fn with_str<F: FnOnce(String)>(s: &str, f: F) {
         f(Lua::new().create_string(s).unwrap());
     }
@@ -21,7 +21,7 @@ fn compare() {
 }
 
 #[test]
-fn string_views() -> Result<()> {
+fn test_string_views() -> Result<()> {
     let lua = Lua::new();
 
     lua.load(
@@ -39,6 +39,10 @@ fn string_views() -> Result<()> {
     let empty: String = 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?"
+    );
     assert_eq!(
         ok.as_bytes(),
         &b"null bytes are valid utf-8, wh\0 knew?"[..]
@@ -55,7 +59,7 @@ fn string_views() -> Result<()> {
 }
 
 #[test]
-fn raw_string() -> Result<()> {
+fn test_raw_string() -> Result<()> {
     let lua = Lua::new();
 
     let rs = lua.create_string(&[0, 1, 2, 3, 0, 1, 2, 3])?;

tests/tests.rs

@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 use std::iter::FromIterator;
 use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::string::String as StdString;
@@ -82,6 +83,7 @@ fn test_safety() -> Result<()> {
 #[test]
 fn test_load() -> Result<()> {
     let lua = Lua::new();
+
     let func = lua.load("return 1+2").into_function()?;
     let result: i32 = func.call(())?;
     assert_eq!(result, 3);
@@ -394,7 +396,7 @@ fn test_panic() -> Result<()> {
         Ok(lua)
     }
 
-    // Test triggerting Lua error passing Rust panic (must be resumed)
+    // Test triggering Lua error with sending Rust panic (must be resumed)
     {
         let lua = make_lua(LuaOptions::default())?;
 
@@ -450,7 +452,7 @@ fn test_panic() -> Result<()> {
         }
     }
 
-    // Test representing rust panic as a string
+    // Test representing Rust panic as a string
     match catch_unwind(|| -> Result<()> {
         let lua = make_lua(LuaOptions::default())?;
         lua.load(
@@ -485,7 +487,7 @@ fn test_panic() -> Result<()> {
         Err(p) => assert!(*p.downcast::<StdString>().unwrap() == "rust panic from lua"),
     }
 
-    // Test enabling `catch_rust_panics` option / xpcall correctness
+    // Test disabling `catch_rust_panics` option / xpcall correctness
     match catch_unwind(|| -> Result<()> {
         let lua = make_lua(LuaOptions::new().catch_rust_panics(false))?;
         lua.load(
@@ -611,7 +613,7 @@ fn test_pcall_xpcall() -> Result<()> {
     assert!(lua.load("xpcall()").exec().is_err());
     assert!(lua.load("xpcall(function() end)").exec().is_err());
 
-    // Lua 5.3/5.2 / LuaJIT compatible version of xpcall
+    // Lua >= 5.2 compatible version of xpcall for 5.1
     #[cfg(feature = "lua51")]
     lua.load(
         r#"
@@ -797,6 +799,23 @@ fn test_drop_registry_value() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_lua_registry_hash() -> Result<()> {
+    let lua = Lua::new();
+
+    let r1 = Arc::new(lua.create_registry_value("value1")?);
+    let r2 = Arc::new(lua.create_registry_value("value2")?);
+
+    let mut map = HashMap::new();
+    map.insert(r1.clone(), "value1");
+    map.insert(r2.clone(), "value2");
+
+    assert_eq!(map[&r1], "value1");
+    assert_eq!(map[&r2], "value2");
+
+    Ok(())
+}
+
 #[test]
 fn test_lua_registry_ownership() -> Result<()> {
     let lua1 = Lua::new();
@@ -828,7 +847,26 @@ fn test_mismatched_registry_key() -> Result<()> {
 }
 
 #[test]
-fn too_many_returns() -> Result<()> {
+fn test_recursion() -> Result<()> {
+    let lua = Lua::new();
+
+    let f = lua.create_function(move |lua, i: i32| {
+        if i < 64 {
+            lua.globals()
+                .get::<_, Function>("f")?
+                .call::<_, ()>(i + 1)?;
+        }
+        Ok(())
+    })?;
+
+    lua.globals().set("f", f.clone())?;
+    f.call::<_, ()>(1)?;
+
+    Ok(())
+}
+
+#[test]
+fn test_too_many_returns() -> Result<()> {
     let lua = Lua::new();
     let f = lua.create_function(|_, ()| Ok(Variadic::from_iter(1..1000000)))?;
     assert!(f.call::<_, Vec<u32>>(()).is_err());
@@ -836,7 +874,7 @@ fn too_many_returns() -> Result<()> {
 }
 
 #[test]
-fn too_many_arguments() -> Result<()> {
+fn test_too_many_arguments() -> Result<()> {
     let lua = Lua::new();
     lua.load("function test(...) end").exec()?;
     let args = Variadic::from_iter(1..1000000);
@@ -850,23 +888,20 @@ fn too_many_arguments() -> Result<()> {
 
 #[test]
 #[cfg(not(feature = "luajit"))]
-fn too_many_recursions() -> Result<()> {
+fn test_too_many_recursions() -> Result<()> {
     let lua = Lua::new();
+
     let f = lua
         .create_function(move |lua, ()| lua.globals().get::<_, Function>("f")?.call::<_, ()>(()))?;
-    lua.globals().set("f", f)?;
 
-    assert!(lua
-        .globals()
-        .get::<_, Function>("f")?
-        .call::<_, ()>(())
-        .is_err());
+    lua.globals().set("f", f.clone())?;
+    assert!(f.call::<_, ()>(()).is_err());
 
     Ok(())
 }
 
 #[test]
-fn too_many_binds() -> Result<()> {
+fn test_too_many_binds() -> Result<()> {
     let lua = Lua::new();
     let globals = lua.globals();
     lua.load(
@@ -905,7 +940,7 @@ fn test_ref_stack_exhaustion() {
 }
 
 #[test]
-fn large_args() -> Result<()> {
+fn test_large_args() -> Result<()> {
     let lua = Lua::new();
     let globals = lua.globals();
 
@@ -940,7 +975,7 @@ fn large_args() -> Result<()> {
 }
 
 #[test]
-fn large_args_ref() -> Result<()> {
+fn test_large_args_ref() -> Result<()> {
     let lua = Lua::new();
 
     let f = lua.create_function(|_, args: Variadic<String>| {
@@ -956,7 +991,7 @@ fn large_args_ref() -> Result<()> {
 }
 
 #[test]
-fn chunk_env() -> Result<()> {
+fn test_chunk_env() -> Result<()> {
     let lua = Lua::new();
 
     let assert: Function = lua.globals().get("assert")?;
@@ -998,7 +1033,7 @@ fn chunk_env() -> Result<()> {
 }
 
 #[test]
-fn context_thread() -> Result<()> {
+fn test_context_thread() -> Result<()> {
     let lua = Lua::new();
 
     let f = lua
@@ -1021,7 +1056,7 @@ fn context_thread() -> Result<()> {
 
 #[test]
 #[cfg(any(feature = "lua51", feature = "luajit"))]
-fn context_thread_51() -> Result<()> {
+fn test_context_thread_51() -> Result<()> {
     let lua = Lua::new();
 
     let thread = lua.create_thread(

tests/thread.rs

@@ -93,8 +93,8 @@ fn test_thread() -> Result<()> {
     Ok(())
 }
 
-#[cfg(any(feature = "lua54", all(feature = "luajit", feature = "vendored")))]
 #[test]
+#[cfg(any(feature = "lua54", all(feature = "luajit", feature = "vendored")))]
 fn test_thread_reset() -> Result<()> {
     use mlua::{AnyUserData, UserData};
     use std::sync::Arc;
@@ -137,7 +137,7 @@ fn test_thread_reset() -> Result<()> {
 }
 
 #[test]
-fn coroutine_from_closure() -> Result<()> {
+fn test_coroutine_from_closure() -> Result<()> {
     let lua = Lua::new();
 
     let thrd_main = lua.create_function(|_, ()| Ok(()))?;
@@ -161,7 +161,7 @@ fn coroutine_from_closure() -> Result<()> {
 }
 
 #[test]
-fn coroutine_panic() {
+fn test_coroutine_panic() {
     match catch_unwind(|| -> Result<()> {
         // check that coroutines propagate panics correctly
         let lua = Lua::new();

tests/userdata.rs

@@ -1,4 +1,7 @@
-use std::sync::Arc;
+use std::sync::{Arc, Mutex, RwLock};
+
+#[cfg(not(feature = "send"))]
+use std::{cell::RefCell, rc::Rc};
 
 #[cfg(feature = "lua54")]
 use std::sync::atomic::{AtomicI64, Ordering};
@@ -359,6 +362,12 @@ fn test_fields() -> Result<()> {
                 index.set("f", 321)?;
                 Ok(index)
             });
+            fields.add_meta_field_with(MetaMethod::NewIndex, |lua| {
+                lua.create_function(|lua, (_, field, val): (AnyUserData, String, Value)| {
+                    lua.globals().set(field, val)?;
+                    Ok(())
+                })
+            })
         }
     }
 
@@ -376,6 +385,9 @@ fn test_fields() -> Result<()> {
         assert(ud.uval == "hello")
 
         assert(ud.f == 321)
+
+        ud.unknown = 789
+        assert(unknown == 789)
     "#,
     )
     .exec()?;
@@ -451,3 +463,69 @@ fn test_metatable() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_userdata_wrapped() -> Result<()> {
+    struct MyUserData(i64);
+
+    impl UserData for MyUserData {
+        fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+            fields.add_field_method_get("data", |_, this| Ok(this.0));
+            fields.add_field_method_set("data", |_, this, val| {
+                this.0 = val;
+                Ok(())
+            })
+        }
+    }
+
+    let lua = Lua::new();
+    let globals = lua.globals();
+
+    #[cfg(not(feature = "send"))]
+    {
+        let ud1 = Rc::new(RefCell::new(MyUserData(1)));
+        globals.set("rc_refcell_ud", ud1.clone())?;
+        lua.load(
+            r#"
+            rc_refcell_ud.data = rc_refcell_ud.data + 1
+            assert(rc_refcell_ud.data == 2)
+        "#,
+        )
+        .exec()?;
+        assert_eq!(ud1.borrow().0, 2);
+        globals.set("rc_refcell_ud", Nil)?;
+        lua.gc_collect()?;
+        assert_eq!(Rc::strong_count(&ud1), 1);
+    }
+
+    let ud2 = Arc::new(Mutex::new(MyUserData(2)));
+    globals.set("arc_mutex_ud", ud2.clone())?;
+    lua.load(
+        r#"
+        arc_mutex_ud.data = arc_mutex_ud.data + 1
+        assert(arc_mutex_ud.data == 3)
+    "#,
+    )
+    .exec()?;
+    assert_eq!(ud2.lock().unwrap().0, 3);
+
+    let ud3 = Arc::new(RwLock::new(MyUserData(3)));
+    globals.set("arc_rwlock_ud", ud3.clone())?;
+    lua.load(
+        r#"
+        arc_rwlock_ud.data = arc_rwlock_ud.data + 1
+        assert(arc_rwlock_ud.data == 4)
+    "#,
+    )
+    .exec()?;
+    assert_eq!(ud3.read().unwrap().0, 4);
+
+    // Test drop
+    globals.set("arc_mutex_ud", Nil)?;
+    globals.set("arc_rwlock_ud", Nil)?;
+    lua.gc_collect()?;
+    assert_eq!(Arc::strong_count(&ud2), 1);
+    assert_eq!(Arc::strong_count(&ud3), 1);
+
+    Ok(())
+}