pythonGH-115060: Speed up pathlib.Path.glob() by omitting initial `…

…stat()`

Since 6258844, paths that might not exist can be fed into pathlib's
globbing implementation, which will call `os.scandir()` / `os.lstat()` only
when strictly necessary. This allows us to drop an initial `self.is_dir()`
call, which saves a `stat()`.

Doc/library/pathlib.rst

@@ -1004,9 +1004,7 @@ call fails (for example because the path doesn't exist).
    .. seealso::
       :ref:`pathlib-pattern-language` documentation.
 
-   This method calls :meth:`Path.is_dir` on the top-level directory and
-   propagates any :exc:`OSError` exception that is raised. Subsequent
-   :exc:`OSError` exceptions from scanning directories are suppressed.
+   This method suppresses any :exc:`OSError` exceptions raised while scanning.
 
    By default, or when the *case_sensitive* keyword-only argument is set to
    ``None``, this method matches paths using platform-specific casing rules:

Lib/pathlib/__init__.py

@@ -607,11 +607,9 @@ def glob(self, pattern, *, case_sensitive=None, recurse_symlinks=False):
         if raw[-1] in (self.parser.sep, self.parser.altsep):
             # GH-65238: pathlib doesn't preserve trailing slash. Add it back.
             parts.append('')
-        if not self.is_dir():
-            return iter([])
         select = self._glob_selector(parts[::-1], case_sensitive, recurse_symlinks)
         root = str(self)
-        paths = select(root, exists=True)
+        paths = select(root)
 
         # Normalize results
         if root == '.':

Lib/pathlib/_abc.py

@@ -705,10 +705,8 @@ def glob(self, pattern, *, case_sensitive=None, recurse_symlinks=True):
         anchor, parts = pattern._stack
         if anchor:
             raise NotImplementedError("Non-relative patterns are unsupported")
-        if not self.is_dir():
-            return iter([])
         select = self._glob_selector(parts, case_sensitive, recurse_symlinks)
-        return select(self, exists=True)
+        return select(self)
 
     def rglob(self, pattern, *, case_sensitive=None, recurse_symlinks=True):
         """Recursively yield all existing files (of any kind, including

Misc/NEWS.d/next/Library/2024-04-13-01-45-15.gh-issue-115060.IxoM03.rst

@@ -0,0 +1,3 @@
+Speed up :meth:`pathlib.Path.glob` my omitting an initial
+:meth:`~pathlib.Path.is_dir` call. As a result of this change,
+:meth:`~pathlib.Path.glob` can no longer raise :exc:`OSError`.