Remove monkeypatching of _msvccompiler.

[jaraco]

The monkeypatch indicates that the functionality was ported from Python 3.8, so the version in distutils should be adequate now.

I note that there have been some changes to this module since it was ported from Python 3.8, including:

• Arm support Check MSVC arm64 variant on arm64 host #4555 (addressed by Use arm64 MSVC on arm64 Windows distutils#285)
• requiresAny support Implement workaround for missing -requiresAny (only available on VS 2017 > 15.6) #3950 (addressed by Consolidate VS 2017 support from Setuptools distutils#289)
• VS/VC 2017 support Added Visual Studio Express 2017 support #2663 (addressed by Consolidate VS 2017 support from Setuptools distutils#289)
• Resolving error text issue (#2302) #2334 (addressed by Consolidate VS 2017 support from Setuptools distutils#289)
• Use CPython 3.8.0 mechanism to find msvc 14+ #1904 (this was the port from Python 3.8.0)

We'll want to have those issues supported by pypa/distutils if not fully dropping support for stdlib distutils before enacting this change.

Merge after #4606.

Summary of changes

Closes

Pull Request Checklist

• Changes have tests
• News fragment added in newsfragments/.
  (See documentation for details)

[abravalheri]

There are probably some changes in setuptools/msvc.py that need to be ported to distutils (at least _msvc14_find_vc2017)

[jaraco]

I updated the description to highlight the relevant changes.

We'll want to have those issues supported by pypa/distutils if not fully dropping support for stdlib distutils before enacting this change.

On further consideration, I think it's safe to force Windows users who need improved VC/VS support not to use distutils from the stdlib, so support in pypa/distutils should be adequate.

[jaraco]

I've added #1904 to the list of changes to review. There are a lot of changes in there that don't match with what's in distutils, presumably because distutils has evolved since Python 3.8. I'm hoping it's not the case that these additional behaviors (like those to find_vcvarsall) weren't subtly added in #1904.

[jaraco]

Oh, interesting. So it looks like the contents in msvc were indeed drawn from 3.8.0 but that implementation changed substantially throughout the 3.8 series (especially in python/cpython@0d20364). This means that although bugs were fixed in stdlib distutils, those fixes have been largely unavailable to Setuptools' users.

We do want to adopt the fixes that are applied in distutils (and not go backward on those changes).

That means that there's liable to be more churn when adopting this change than I'd like, as distutils can't be made a drop-in replacement for what setuptools users expect. Depending on the amount of disruption, we may need to yank releases or back out changes until the differences can be assessed.

[saschanaz]

Arm support #4555 (addressed by pypa/distutils#285)

But those are independent, no? The former is to find vcvarsall and the latter is to get the right tool from that vcvarsall.

[saschanaz]

Oh, folded into 196d44b. Never mind then.

[jaraco]

Thanks for reviewing. Please let me know how Setuptools 74 works for you. I'm happy to address any unexpected failures promptly.

[saschanaz]

The linked issues are unhappy with setuptools.msvc.EnvironmentInfo being removed, is there an equivalent now?

[jaraco]

There isn't. I did not realize they were in use. I was assuming and did not verify that those classes were only previously used for internal implementation details for functionality that had been removed.

Since users are relying on it, we should bring them back, and add some tests.