Access sysconfig paths through pyodide config CLI

[agriyakhetarpal]

Description

This PR is a re-do of pyodide/pyodide#4947, which aimed to add the include directory containing the Python interpreter headers. This PR goes one step further and adds a way to access all of the paths listed under sysconfig.get_paths(). These paths are available in the default configuration values under pyodide config list and are accessible through pyodide config get <variable name>, say pyodide config get pyodide_sysconfig_include. These contain the pyodide_sysconfig prefix to prevent any potential conflicts with any of the other computed variables.

Note

Please refer to the description for the PR above for the reasoning behind this change.

Checklist

• Tested via TestConfigManager_OutOfTree::test_default_config, so an additional test isn't needed
• CHANGELOG entry – addressed in 57ef6f2

[agriyakhetarpal]

Personally, I'm not a fan of the pyodide_sysconfig prefix, but I think it helps avoid us being ambiguous. Also, I think python_sysconfig would be a better prefix instead of pyodide_sysconfig – this is ready for review, @ryanking13 (I don't have permissions to request reviews on this repository)

[ryanking13]

Thanks @agriyakhetarpal!

pyodide_sysconfig_*

Maybe just sysconfig_*? pyodide prefix seems redundant to me.

[ryanking13]

This would retrieve the host Python's sysconfig values, not those in the cross build env. We should parse these values from the _sysconfigdata__emscripten_wasm32-emscripten.py file in the xbuildenv.

[agriyakhetarpal]

Where should I retrieve this file from the cross-build environment? I have noted that I can get the file when I do pyodide xbuildenv install, but if there's already a programmatic way to access this, I can use that instead of writing my own methods.

[ryanking13]

Here is the code we locate the sysconfig file. Since it uses the variables in the Makefile.envs, you'll need to modify it a bit to use it in the config manager to prevent cyclic import.

pyodide-build/pyodide_build/pypabuild.py

Lines 98 to 102 in fac0109

	sysconfigdata_name = get_build_flag("SYSCONFIG_NAME")
	sysconfigdata_path = (
	Path(get_build_flag("TARGETINSTALLDIR"))
	/ f"sysconfigdata/{sysconfigdata_name}.py"
	)

I think you'll also need to read the sysconfig.py and how it retrieves the value from the sysconfig file, as we cannot directly use sysconfig module here.

[ryanking13]

There are only eight values in sysconfig.get_paths(), so, I think it is okay to list all of them, which will be more explicit and make the code more readable.