Add support for 32-bit

[Esption]

Trying to do cargo build --target i686-pc-windows-msvc fails to build. It is possible to go in and get it to manually compile by editing godt-ffi/src/opaque.rs to have an align(4) instead of 8, and the OpaqueObject in godot-ffi/src/gen/central.rs from 8uszie to 4usize (you need to wait until after you see the fail build for that, because of codegen). Likely there are other things in that need to be updated as well, but at a minimum that will successfully cause it compile. I wasn't able to figure out where that codegen is actually happening. After editing those two things, the creeps example will start and run, but appears to crash on the anim_names.to_vec() in the rust/src/mob.rs

[lilizoey]

i think we need to change this:

    // For float/double inference, see:
    // * https://github.com/godotengine/godot-proposals/issues/892
    // * https://github.com/godotengine/godot-cpp/pull/728
    #[cfg(feature = "double-precision")]
    let build_config = "double_64"; // TODO infer this
    #[cfg(not(feature = "double-precision"))]
    let build_config = "float_64"; // TODO infer this

in here to the respective x_32 build configs for this.

[Esption]

So, I'm pretty sure the codegen for the Opaques originates from godot4-prebuilt::load_gdextension_json() called in godot-codegen/src/lib.rs
I guess just need to give that a different target?

[lilizoey]

yea probably, we can likely use https://doc.rust-lang.org/reference/conditional-compilation.html#target_pointer_width this cfg flag to decide between which representation to use

[Esption]

Not sure if should mention here or over there, but
https://github.com/godot-rust/godot4-prebuilt
seems to explictly generate for 64-bit targets. It seems fine for the most part with one exception. The built-in tests will fail due to the widths assuming 64-bit. If we added other targets, it would be nice to get win32/linux32/wasm added in there. Example command is to just run cargo test --no-default-features --target i686-pc-windows-msvc

Best I can tell, that's the only reason the itest suite fails as a whole against 32-bit targets, but hard to tell atm.

[Bromeon]

So this would need:

• a godot4-prebuilt configuration which generates artifacts for 32-bit
• a CI job in gdext that runs unit tests for it
  Anything else?

Probably it's good enough to combine this with WASM for now...

[Esption]

AFAIK yes that should be the final thing to tick off 32-bit support.