Use CPython 3.8.0 mechanism to find msvc 14+

[mayeut]

Summary of changes

Update msvc.py to use CPython 3.8.0 mechanism to find msvc 14+ as recommended in this comment.

Closes #1903

This PR has been tested as part of cibuildwheel tests using various CI providers.
Please note that I can't test it more thoroughly cause I don't have any Windows environment at hand (except for CI which requires very long iterations).

Pull Request Checklist

• Changes have tests
• News fragment added in changelog.d. See documentation for details

[JGoutin]

Using a Python 3.8 back port instead of the current mechanism seem to be the good way to do.

This also allow to completely drop the old mechanism that become unused. This will make this file far more easy to maintain. Note that this will remove the following:

• VC 2010 support, only used by Python 3.4 that is deprecated.
• Microsoft Windows SDK 6.1 and 7.0 support, tools that are deprecated and where removed from download by Microsoft. (And there is still the "VC for python 2.7" that replace them)

I sent you a PR with the following changes:

• Drop the old mechanism.
• Fixed a missing import.
• PEP8 + Add python 3.8 backport comment.

I do not have a Windows right now to do more tests on it.

There are maybe tests with Python 3.8 that can be back-ported too.

[mayeut]

Thanks @JGoutin, this is much cleaner indeed. All CI tests of cibuildwheel are passing with your version of msvc.py. I will correct the missing import in the meantime (itertools.count() right ?)

If @pypa/setuptools-developers are ok with your notes (Microsoft Windows SDK 6.1 and 7.0, Python 3.4 support dropped), I'll merge that in this PR.

[mayeut]

There are maybe tests with Python 3.8 that can be back-ported too.

Indeed, I'll check if I can add those:
https://github.com/python/cpython/blob/master/Lib/distutils/tests/test_msvccompiler.py

[JGoutin]

(itertools.count() right ?)

It's exactly that.

[JGoutin]

Concerning the drop of the old mechanism (and VC2010 support), Python 3.4 will be dropped with #1908.

This will also fix the issue #1902

[JGoutin]

If @pypa/setuptools-developers are ok with your notes (Microsoft Windows SDK 6.1 and 7.0, Python 3.4 support dropped), I'll merge that in this PR.

#1908 is merged, Python 3.4 support is dropped from setuptools.

[mayeut]

I will drop python 3.4 support in msvc.py from the PR

Edit: I won't drop python 3.4

Since python 3.4 uses the same code base as python 2.7, I'd rather not change it. It'll be easier to drop as a whole once python 2.7 support is really removed from setuptools.

[JGoutin]

Edit: I won't drop python 3.4

Since python 3.4 uses the same code base as python 2.7, I'd rather not change it. It'll be easier to drop as a whole once python 2.7 support is really removed from setuptools.

Removing the python 3.4 support will not remove the Python 2.7 support. It will only remove the
Microsoft Windows SDK 6.1 and 7.0 support, that are deprecated and not available anymore.

Python 2.7 requires msvc9_find_vcvarsall & msvc9_query_vcvarsall functions.
In the PR code, theses functions are still available: https://github.com/JGoutin/setuptools/blob/msvc-python3.5/setuptools/msvc.py#L56.

[mayeut]

@JGoutin,
I'd rather not change python 2.7 support at all to prevent any regressions, even if unlikely. So, in my opinion, removing Microsoft Windows SDK 6.1 and 7.0 support is not an option.

[mayeut]

@jaraco,
can you review this PR please ?

[jaraco]

Looks good to me. Thanks!

[jaraco]

Released as 45.3.0