gh-160904: Correct os.path.normcase documentation for POSIX

Doc/library/os.path.rst

@@ -415,7 +415,8 @@ the :mod:`glob` module.)
 
    Normalize the case of a pathname.  On Windows, convert all characters in the
    pathname to lowercase, and also convert forward slashes to backward slashes.
-   On other operating systems, return the path unchanged.
+   On other operating systems, this calls :func:`os.fspath` to convert
+   path-like objects to ``str`` or ``bytes``.
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.

Lib/posixpath.py

@@ -52,7 +52,11 @@ def _get_sep(path):
 # (another function should be defined to do that).
 
 def normcase(s, /):
-    """Normalize case of pathname.  Has no effect under Posix"""
+    """Normalize case of pathname.  Has no effect under Posix.
+
+    On Posix, this calls os.fspath(s), which converts path-like objects
+    to str or bytes.
+    """
     return os.fspath(s)
 
 

Misc/NEWS.d/next/Documentation/2026-11-06-01-07-31.gh-issue-160904.normcase-doc.rst

@@ -0,0 +1 @@
+Fixed the documentation of :func:`os.path.normcase` to clarify that on Posix it calls :func:`os.fspath`, which converts path-like objects to `str` or `bytes`.