The semantics of parameter "resolve_host" in "urllib.request.url2pathname()" seems reversed as is documented

[hikorp]

Bug report

Bug description:

from urllib.request import url2pathname
url = 'file:///C:/Program%20Files'
url2pathname(url, require_scheme=True) # when True, "file:" should be included
'C:\Program Files'
url2pathname(url, require_scheme=False) # when False, "file:" should be omitted
'file:\\\C:\Program Files'

CPython versions tested on:

3.14

Operating systems tested on:

Windows

[tonghuaroot]

require_scheme describes whether the input URL has a file: prefix, not whether the output keeps one. The result is a filesystem path and never contains file:.

With require_scheme=False (the default) the function prepends file: itself (Lib/urllib/request.py), so a URL that already has the scheme becomes file:file:///..., which is your second result.

Correct usage, both returning 'C:\\Program Files':

url2pathname('file:///C:/Program%20Files', require_scheme=True)  # input has the scheme
url2pathname('/C:/Program%20Files')                             # input omits it (default)

So this is working as documented, not a bug.

[hikorp]

Sorry, it's not a bug. @tonghuaroot you are right.