tags.cpython_tags returns an incorrect value when run from a 32-bit VS developer prompt on a 64-bit Windows

[pfmoore]

See pypa/pip#8649.

Basically, cpython_tags is using distutils.get_platform here. It should probably be using get_host_platform - as far as I can tell the only difference is for cross-compilation, and (even if we accept that distutils supports cross-compilation, which I'm not sure it does) when installing wheels, we want to use the host platform, not the target platform (as we're not even building, so "target" makes no sense).

[uranusjr]

Quoting @zooba in bpo-38989:

As you say, [get_host_platform and get_platform are] both private functions, and as we investigated adding a "get_target_platform" function, it turned out that nearly all users were expecting the target platform, so rather than updating everything we added one for the less-common case.

So it may be better for packaging.tags to maintain its own platform tag implementation instead of depending on distutils internals.

[altendky]

Just hit this on GitHub Actions where my 32-bit build for pyqt5-tools was getting 64-bit psutil wheels etc. Would a useful patch be roughly a copy of get_host_platform() minus the cross-build awareness?

[brettcannon]

@altendky without looking at the code, I simply don't know.

[zooba]

So it may be better for packaging.tags to maintain its own platform tag implementation instead of depending on distutils internals.

Yes, this.

[uranusjr]

I think #396 fixed this.

[puetzk]

Confirmed, it now works for me, using python-3.9.4-amd64.exe via a shell launched with "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Common7\Tools\VsDevCmd.bat" -arch=x86 -host_arch=amd64" (so VSCMD_ARG_TGT_ARCH=x86)

from packaging import tags
[str(x) for x in tags.cpython_tags()]

--- pip install packaging==20.9
+++ pip install git+https://github.com/pypa/packaging@c8008265eac83ebf2c3b3c314a682abd4c101de2
-['cp39-cp39-win32', 'cp39-abi3-win32', 'cp39-none-win32', 'cp38-abi3-win32', 'cp37-abi3-win32', 'cp36-abi3-win32', 'cp35-abi3-win32', 'cp34-abi3-win32', 'cp33-abi3-win32', 'cp32-abi3-win32']
+['cp39-cp39-win_amd64', 'cp39-abi3-win_amd64', 'cp39-none-win_amd64', 'cp38-abi3-win_amd64', 'cp37-abi3-win_amd64', 'cp36-abi3-win_amd64', 'cp35-abi3-win_amd64', 'cp34-abi3-win_amd64', 'cp33-abi3-win_amd64', 'cp32-abi3-win_amd64']

[brettcannon]

Thanks for the confirmations! Closing as fixed.