GH-115060: Speed up `pathlib.Path.glob()` by not scanning literal parts (#117732)

Don't bother calling `os.scandir()` to scan for literal pattern segments,
like `foo` in `foo/*.py`. Instead, append the segment(s) as-is and call
through to the next selector with `exists=False`, which signals that the
path might not exist. Subsequent selectors will call `os.scandir()` or
`os.lstat()` to filter out missing paths as needed.

1 files changed, 7 insertions, 1 deletions

diff --git a/Lib/pathlib/_abc.py b/Lib/pathlib/_abc.py
index b6cab0d285a..b51ad6f46d2 100644
--- a/Lib/pathlib/_abc.py
+++ b/Lib/pathlib/_abc.py
@@ -686,8 +686,14 @@ class PathBase(PurePathBase):
     def _glob_selector(self, parts, case_sensitive, recurse_symlinks):
         if case_sensitive is None:
             case_sensitive = _is_case_sensitive(self.parser)
+            case_pedantic = False
+        else:
+            # The user has expressed a case sensitivity choice, but we don't
+            # know the case sensitivity of the underlying filesystem, so we
+            # must use scandir() for everything, including non-wildcard parts.
+            case_pedantic = True
         recursive = True if recurse_symlinks else glob._no_recurse_symlinks
-        globber = self._globber(self.parser.sep, case_sensitive, recursive)
+        globber = self._globber(self.parser.sep, case_sensitive, case_pedantic, recursive)
         return globber.selector(parts)
 
     def glob(self, pattern, *, case_sensitive=None, recurse_symlinks=True):