[nikolchaa]

Fixes #742. Related: #23, #662.

HeapDump::new uses libc stdio (tmpfile, fseek, ftell, rewind, fread, fclose), which the libc crate does not provide for wasm32-unknown-unknown, so the luau feature does not compile for that target.

This PR puts the stdio block behind #[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]. On that target the dump buffer stays empty and HeapDump::new returns None, so Lua::heap_dump() returns the existing "unable to dump heap" error. Two allow attributes silence the unused-code warnings on that target only.

Every other target, including wasm32-unknown-emscripten, compiles exactly the same code as before.

Testing

• cargo test --features "luau vendored": 310 passed, 0 failed, including test_heap_dump.
• cargo clippy --features "luau vendored" -- -D warnings and cargo fmt --all --check: clean.
• cargo build --lib --features "luau vendored" --target wasm32-unknown-unknown, with Luau's C++ built by clang against a wasi-sdk sysroot (LUAU_CXXFLAGS): fails on main with the 7 errors in luau feature fails to compile for wasm32-unknown-unknown (HeapDump uses libc stdio) #742, compiles with this change. Luau then runs in the browser under wasm-bindgen: eval, runtime and syntax errors, pcall and coroutines.

This doesn't make wasm32-unknown-unknown an officially supported target. It only removes the one Rust-side compile error, so projects that provide their own C++ toolchain can use it.

[yahyehussein]

We ran into the same problem building for wasm32-unknown-unknown with wgpu and winit; this fix works for us, and mlua's tests pass natively and on wasm32. Thanks!

[nikolchaa]

We ran into the same problem building for wasm32-unknown-unknown with wgpu and winit; this fix works for us, and mlua's tests pass natively and on wasm32. Thanks!

Glad to hear it worked for you. I hope that this PR will be approved by the maintainer soon.
Cheers! 🍻