Warning for user when Windows default Path Limit is exceeded

[OBITORASU]

Description

This PR generates a warning message for the end-user informing them about the potential errors which might be caused if they have Long Paths disabled on their Windows system. I have used:

from pip._internal.utils.compat import WINDOWS

as the means to check the host OS as suggested by the maintainers and added an if statement to check for the 260 default path length limit when Long Paths is disabled. The if statement will successfully trigger a warning using logger.warning in case the host OS is Windows and the error message length (which also contains the path) is greater than 260 characters.

Fixes Issue #10045

[uranusjr]

Couple of thoughts:

1. error is an exception, so you need to str() it first.
2. We should probably check error.errno to make sure we’re catching a FileNotFoundError.
3. The error message should include a link to some Microsoft documentation. I don’t except people having Long Paths off would understand what set LongPathsEnabled to 1 means.

[OBITORASU]

Couple of thoughts:

1. `error` is an exception, so you need to `str()` it first.

2. We should probably check `error.errno` to make sure we’re catching a `FileNotFoundError`.

3. The error message should include a link to some Microsoft documentation. I don’t except people having Long Paths off would understand what _set LongPathsEnabled to 1_ means.

For the second suggestion. Can I go forward with a check like error.errno == errno.ENOENT? Somewhat like this check if error.errno == errno.EACCES: currently being used in the code.

[uranusjr]

Yeah, sounds right to me.

[OBITORASU]

Yeah, sounds right to me.

And last question I had for the final suggestion, I am going forward with this microsoft documentation in particular: https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=cmd#enable-long-paths-in-windows-10-version-1607-and-later
Hope this is fine.

[uranusjr]

Damn, that’s a long one. I guess that’s the best we can have though, since it’s Microsoft.

[OBITORASU]

Damn, that’s a long one. I guess that’s the best we can have though, since it’s Microsoft.

Yeah that is the only decent one I found which belonged exclusively to Microsoft. As of now I have updated the PR with all the requested changes, please take a look when it is possible for you. Thanks!

[pradyunsg]

LGTM! Happy to have this merged once CI is happy. :)

[pradyunsg]

Thanks for your contribution @OBITORASU! ^>^