Targetting WASM from Rust on OSX

rust_wasm_osx.md

Rust stable (nightly) wasm on osx

Basic setup taken from The Path to Rust on the Web

• Installing managed tools src src2
  • rustup target add wasm32-unknown-emscripten
  • brew install emscripten
  • brew install clang nodejs git - for llvm
• Running cargo build --target=wasm32-unknown-emscripten claims to work but no wasm or js are created
  • emcc -v complains about system llvm not having wasm target
• Install llvm-emscripten src

  CORES=4
  mkdir myfastcall
  cd myfastcall
  git clone https://github.com/kripken/emscripten-fastcomp
  cd emscripten-fastcomp
  git clone https://github.com/kripken/emscripten-fastcomp-clang tools/clang
  mkdir build
  cd build
  cmake .. -DCMAKE_BUILD_TYPE=Release -DLLVM_TARGETS_TO_BUILD="X86;X;JSBackend" -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_TESTS=OFF -DCLANG_INCLUDE_EXAMPLES=OFF -DCLANG_INCLUDE_TESTS=OFF
  make -j${CORES}
  perl -ipe "s/^LLVM_ROOT.*$/LLVM_ROOT = \\\"$(pwd)/bin\\\"" ~/.emscripten
  

• Running cargo build --target=wasm32-unknown-emscripten now generates wasm and js files properly!