I assume the compiler(s) do not run in WASM. Just the build script. The build script just orchestrates the compilers. So you can run any compiler that the build script is given access to, so compiling C/C++ or potentially any other language shouldn’t be an issue.

In theory, you could run the whole compiler (including C) in WASM as well but I don’t think that’s the goal? You kinda need to trust the compiler itself.