how to set up the emscripten toolchain

[Birch-san]

Spun out from @hutzlibu's question:
#9 (comment)

[Birch-san]

which OS are you building this on?

[Birch-san]

I'd recommend installing latest Emscripten (it worked for me on 2.0.5).

Emscripten 2.0.0 and higher removed support for the old fastcomp backend, and use an LLVM backend instead. Thus you'll need at least LLVM 12, because emscripten needs support for -fignore-exceptions. But Emscripten seems to come bundled with its own LLVM distribution, so maybe all you need to do here is "install latest Emscripten".

I think brew install emscripten or brew upgrade emscripten failed for me in some way (didn't pour the LLVM bottle, or poured me one which didn't work). Instead I installed Emscripten using: brew reinstall --build-from-source emscripten. This takes a few hours (compiling LLVM).

[Birch-san]

I'd recommend:

• Clone this repository using --recursive, to ensure that the box2d submodule is available.
  • https://github.com/Birch-san/box2d-wasm/blob/master/README.dev.md#clone-repository
• Compile box2d and Box2D.js with TARGET_TYPE=Debug
  • https://github.com/Birch-san/box2d-wasm/blob/master/box2d-wasm/README.dev.md
• Run the integration-test against your Box2D.js
  • https://github.com/Birch-san/box2d-wasm/tree/master/integration-test

[hutzlibu]

I use Manjaro, a Arch Linux distribution.
Emscripten 2.0.13-1 is in the repo and installing right now. And I see how far I get this evening. I rather not recompile the whole thing, but ... we'll see ;)