[New-bugs-announce] [issue32693] os.path.ismount does not accept bytes objects

[Nikolay Aleksandrovich Pavlov]

New submission from Nikolay Aleksandrovich Pavlov <zyx.vim at gmail.com>:

According to the documentation it ought to accept any path-like object, but actually throws for bytes ones. The trace of logic is the following:

1. ismount() from Lib/ntpath.py is using `os.fpath` which may return either bytes or str: https://github.com/python/cpython/blob/255f7a26da47ca6b7bd1d375b8a04920f68c119c/Lib/ntpath.py#L263.
2. The output is passed to _getvolumepathname unchanged.
3. The clinic defines that function’s only argument as [unicode](https://github.com/python/cpython/blob/255f7a26da47ca6b7bd1d375b8a04920f68c119c/Modules/posixmodule.c#L3793).
4. If clinic was not there it would still require to change how path_wchar is defined below, PyUnicode… functions will not accept bytes object: https://github.com/python/cpython/blob/255f7a26da47ca6b7bd1d375b8a04920f68c119c/Modules/posixmodule.c#L3808.

Suggestion: change `Lib/ntpath.py` to use `os.fsdecode` in place of `os.fspath`.

This is a relay of issue https://github.com/powerline/powerline/issues/1876. Initial reporter observed bug on Python 3.6 (patch unknown), I could see an issue in current master (all links above point to that).

----------
components: Windows
messages: 310936
nosy: Nikolay Aleksandrovich Pavlov, paul.moore, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: os.path.ismount does not accept bytes objects
type: behavior
versions: Python 3.6, Python 3.7

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<https://bugs.python.org/issue32693>
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