Fix: Windows long filename error

[sepehr-rs]

Fixes #13346

This is my first attempt at addressing this issue. I’d appreciate any feedback or suggestions on how to improve the approach or make it more concise.

[notatallshaw]

Hi @sepehr-rs, thanks for your PR, please be aware it may take some time for pip maintainers to review or respond to this PR as all maintainers are currently volunteers.

Though please let me know if you need any assistance fixing the pre-commit errors.

[sepehr-rs]

Hi @notatallshaw, thanks for the update!

Understand the delay — I really appreciate the work the maintainers do.
I've fixed the pre-commit error, so it should be good to go. Please let me know if anything else is needed.

[ichard26]

Hello,

This looks generally right, but I have suggestions to tweak the changelog and comments. I also ask that you add a unit test to verify that this works properly. This function is tested here:

pip/tests/unit/test_command_install.py

Line 125 in e22047b

def test_create_os_error_message(

You simply need to add another case for this specific error.

Thanks for your interest in improving pip! I look forward to merging your contribution once it's ready.

[ichard26]

Suggested change

	# Windows raises EINVAL when a file or folder name exceeds 255 characters,
	# even if long path support is enabled. Add a hint for that case.
	# Windows raises EINVAL when a file*name* or path segment exceeds 255
	# characters, even if long path support is enabled.

It wasn't immediately obvious to me what the difference between this check and the pre-existing hint was. That's my bad, but we can make this clearer :)

[ichard26]

Provide a hint if a system error is raised involving long filenames or path segments on Windows. 

The changelog entry should be worded for the user. No need for "this change will [...]" as that implied.

[ichard26]

Nice use of pathlib!