A wild cross-platform C++ compiler in browser appears: https://engine.xenolith.studio/
TLDR: WASM build of Clang + carefully prepared env.
And the performance is even better than I expected 🤔
Xenolith SDKXenolith — C and C++ SDKA C and C++ SDK. Linux, Windows, macOS and Android from one project, without the Windows SDK or the NDK. One libc, application libraries, a render graph.