Windows has one current directoryper drive, and supports drive-relative paths like 'X:' and 'X:foo.txt'. This makes a conversion from relative to absolute paths more complicated than simply prepending a (single) current directory.

It's correctly handled inntpath.abspath() by calling NT'sGetFullPathNameW() function. But in pathlib we simply prependos.getcwd(), leading to incorrect results:

>>>importos,nt,pathlib>>>os.chdir('Z:/build')>>>os.chdir('C:/')>>>os.path.abspath('Z:')'Z:\\build'>>>nt._getfullpathname('Z:')'Z:\\build'>>>pathlib.Path('Z:').absolute()WindowsPath('Z:')

This bug is present in all versions of CPython pathlib. We can't fix it by callingabspath() because it will also normalize the path, eliding '..' parts.

Linked PRs

• gh-100809: Fix handling of drive-relative paths in pathlib.Path.absolute() #100812
• [3.11] gh-100809: Fix handling of drive-relative paths in pathlib.Path.absolute() (GH-100812) #101993