Add section on building for Emscripten #1533
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Heavily copied from Brett's WASI guide.
getting-started/setup-building.rst
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| Building for Emscripten requires doing a cross-build where you have a *build* | ||
| Python to help produce a Emscripten build of CPython. This means you build | ||
| CPython twice: once to have a version of Python for the build system to use and | ||
| another that's the build you ultimately care about (that is, the build Python is | ||
| not meant for use by you directly, only the build system). |
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Instead of (almost) duplicating things, maybe this could refer (and link) to the section above, e.g.:
"Like WASI, you will have to build Python twice."
I haven't looked at them side-by-side to see how similar they are, but if they are quite similar another option is merging the two sections and using tabs where they are different.
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I think it's better to duplicate since there's no reason to think they won't diverge in the future. And I don't want to cause trouble for @brettcannon. Let's see what he thinks.
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I'm fine with duplication to avoid issues for accidental divergence.
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Do note that I didn't add the WASI docs until WASI explicitly reached tier 2. I don't know if we have a defined policy around this, though, beyond me just wanting to personally wait until I reached the tier 2 milestone. |
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
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Thanks for the edits @hugovk! |
| # Install Emscripten | ||
| git clone emscripten/emsdk | ||
| ./emsdk/emsdk install 4.0.5 | ||
| ./emsdk/emsdk activate 4.0.5 |
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As a safety catch for the future - do we want to flag that this version number is significant, and you should be using the version that Python is targeting?
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How do people figure out which version Python is targeting?
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I guess that's the question for the documentation to resolve :-)
Right now, I'd say it's a case of "check the Emscripten README to find the version you need".
Longer term, maybe it would be worth adding a helper entry point to the Tools/wasm/emscripten script that will print/verify the required emscripten version? That would mean the emscripten version is defined in code, and can be checked at runtime.
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You could also define a container in https://github.com/python/cpython-devcontainers/ and somehow specify which build that branch of CPython is tied to.
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Heavily copied from Brett's WASI guide.
📚 Documentation preview 📚: https://cpython-devguide--1533.org.readthedocs.build/getting-started/setup-building/#emscripten