[3.12] pythonGH-106330: Fix matching of empty path in pathlib.PurePath.match() (pythonGH-106331)

We match paths using the `_lines` attribute, which is derived from the
path's string representation. The bug arises because an empty path's string
representation is `'.'` (not `''`), which is matched by the `'*'` wildcard.
(cherry picked from commit b4efdf8)

Co-authored-by: Barney Gale <[email protected]>

Author: barneygale

Lib/pathlib.py

@@ -501,8 +501,12 @@ def _lines(self):
         try:
             return self._lines_cached
         except AttributeError:
-            trans = _SWAP_SEP_AND_NEWLINE[self._flavour.sep]
-            self._lines_cached = str(self).translate(trans)
+            path_str = str(self)
+            if path_str == '.':
+                self._lines_cached = ''
+            else:
+                trans = _SWAP_SEP_AND_NEWLINE[self._flavour.sep]
+                self._lines_cached = path_str.translate(trans)
             return self._lines_cached
 
     def __eq__(self, other):

Lib/test/test_pathlib.py

@@ -317,6 +317,10 @@ def test_match_common(self):
         self.assertTrue(P('A.py').match('a.PY', case_sensitive=False))
         self.assertFalse(P('c:/a/B.Py').match('C:/A/*.pY', case_sensitive=True))
         self.assertTrue(P('/a/b/c.py').match('/A/*/*.Py', case_sensitive=False))
+        # Matching against empty path
+        self.assertFalse(P().match('*'))
+        self.assertTrue(P().match('**'))
+        self.assertFalse(P().match('**/*'))
 
     def test_ordering_common(self):
         # Ordering is tuple-alike.

Misc/NEWS.d/next/Library/2023-07-02-10-56-41.gh-issue-106330.QSkIUH.rst

@@ -0,0 +1,2 @@
+Fix incorrect matching of empty paths in :meth:`pathlib.PurePath.match`.
+This bug was introduced in Python 3.12.0 beta 1.