René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Disagreement between `PureWindowsPath.relative_to()` and `ntpath.relpath()` with rootless drives","articleBody":"On Windows, the path `C:` means \"the current directory on the C: drive\".\r\n\r\nBut pathlib's `relative_to()` treats it as the immediate parent of `C:\\`. This makes sense lexographically, but it's inconsistent with everything else:\r\n\r\n```python\r\nC:\\Users\\Barney\u003epython\r\n\u003e\u003e\u003e import ntpath, pathlib\r\n\u003e\u003e\u003e ntpath.relpath('C:/Windows', 'C:/Users/Barney')\r\n'..\\\\..\\\\Windows'\r\n\u003e\u003e\u003e ntpath.relpath('C:/Windows', '.')\r\n'..\\\\..\\\\Windows'\r\n\u003e\u003e\u003e ntpath.relpath('C:/Windows', 'C:')\r\n'..\\\\..\\\\Windows'\r\n\u003e\u003e\u003e pathlib.Path('C:/Windows').relative_to('C:/Users/Barney', walk_up=True)\r\nWindowsPath('../../Windows')\r\n\u003e\u003e\u003e pathlib.Path('C:/Windows').relative_to('.', walk_up=True)\r\nValueError: One path is relative and the other is absolute.\r\n\u003e\u003e\u003e pathlib.Path('C:/Windows').relative_to('C:')\r\nWindowsPath('/Windows')  # should be ValueError, as we're mixing absolute + relative paths\r\n```\r\n\r\nThis prevents us from using `relpath()` from pathlib, and renders the two implementations incompatible. Booo! Also prevents us from simplifying `is_relative_to()` down to `other == self or other in self.parents`\r\n\r\nSpecial cases aren't special enough to break the rules. Let's make these compatible!\r\n\r\nPrevious discussion: #84538\r\n\r\n\u003c!-- gh-pr-number: gh-99031 --\u003e\r\n* PR: gh-99031\r\n\u003c!-- /gh-pr-number --\u003e\r\n","author":{"url":"https://github.com/barneygale","@type":"Person","name":"barneygale"},"datePublished":"2022-11-02T23:21:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/99029/cpython/issues/99029"}