GH-106330: Fix matching of empty path in pathlib.PurePath.match() (G…

…H-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.

Lib/pathlib.py

@@ -463,8 +463,12 @@ 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

@@ -384,6 +384,10 @@ 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.