The compatibility problems between Rust and Emscripten versions are assumed to stem from differing LLVM versions. This combination will be used in the following sections of this tutorial.This guide focuses on building the export template yourself with a recent version of Emscripten.Īs of you also need to use a Rust nightly build. It might be possible to use it if build your Rust code with that exact version, but extra compiler flags may be needed. Godot 3.5's prebuilt HTML5 export template is built with Emscripten 3.1.10. Add the following to your workspace's/project's Cargo.toml:ĭisclaimer: Currently, the following steps are only tested and confirmed to work on Linux. As a workaround, you can set opt-level = 1 in debug builds, which reduces the build size.Debug builds may not work due to their large size.See this issue for more details and instructions for failing experimental build. In particular, Godot export template should be built before the GDNative library.Īlso note that wasm32-unknown-emscripten is a 32-bit target, which can cause problems with crates incorrectly assuming that usize is 64 bits wide.

This means that the order in which steps are completed matters.

You can check which versions of Emscripten/Rust you are using like this: emcc -vĪ list of compatible Rust and Emscripten versions are given in the next section.Įmscripten uses a cache to store build artifacts and header files. build the HTML5 export template yourself.install a specific version of Emscripten.

In practice, this means you probably have to do some or all of these things: Since Emscripten does not offer a stable ABI between versions, your code and the Godot export template have to be built with the same Emscripten version, which also needs to be compatible with the Rust compiler version you are using. The Godot HTML5 export templates are built with Emscripten, so you need to build your Rust code for the wasm32-unknown-emscripten target ( wasm32-unknown-unknown will not work). Versioning and supported platformsĮxporting to HTML5 works just like exporting to other platforms, however there are some things that can make the process a bit tricky and require extra attention.

Html5 compiler