GH-130798: Add type hints to pathlib.types

.github/workflows/mypy.yml

@@ -41,6 +41,7 @@ jobs:
       matrix:
         target: [
           "Lib/_pyrepl",
+          "Lib/pathlib",
           "Lib/test/libregrtest",
           "Tools/build",
           "Tools/cases_generator",

Lib/pathlib/__init__.py

@@ -12,11 +12,18 @@
 import posixpath
 import sys
 from errno import *
-from glob import _StringGlobber, _no_recurse_symlinks
+from glob import _StringGlobber, _no_recurse_symlinks  # type: ignore[attr-defined]
 from itertools import chain
 from stat import S_ISDIR, S_ISREG, S_ISSOCK, S_ISBLK, S_ISCHR, S_ISFIFO
 from _collections_abc import Sequence
 
+# types
+if False:
+    from types import ModuleType
+
+    pwd: ModuleType | None
+    grp: ModuleType | None
+
 try:
     import pwd
 except ImportError:
@@ -26,7 +33,7 @@
 except ImportError:
     grp = None
 
-from pathlib._os import (
+from ._os import (
     PathInfo, DirEntryInfo,
     ensure_different_files, ensure_distinct_paths,
     copyfile2, copyfileobj, magic_open, copy_info,
@@ -46,7 +53,7 @@ class UnsupportedOperation(NotImplementedError):
     pass
 
 
-class _PathParents(Sequence):
+class _PathParents(Sequence["PurePath"]):
     """This object provides sequence-like access to the logical ancestors
     of a path.  Don't try to construct it yourself."""
     __slots__ = ('_path', '_drv', '_root', '_tail')

Lib/pathlib/_os.py

@@ -7,6 +7,23 @@
 import io
 import os
 import sys
+
+# typing
+if False:
+    from collections.abc import Callable
+    from types import ModuleType
+
+    type CopyFunc = Callable[[int, int], None]
+
+    fcntl: ModuleType | None
+    posix: ModuleType | None
+    _winapi: ModuleType | None
+    _ficlone: CopyFunc | None
+    _fcopyfile: CopyFunc | None
+    _copy_file_range: CopyFunc | None
+    _sendfile: CopyFunc | None
+    copyfile2: CopyFunc | None
+
 try:
     import fcntl
 except ImportError:

Lib/pathlib/mypy.ini

@@ -0,0 +1,25 @@
+# Config file for running mypy on pathlib.
+# Run mypy by invoking `mypy --config-file Lib/pathlib/mypy.ini`
+# on the command-line from the repo root
+
+[mypy]
+files = Lib/pathlib
+mypy_path = $MYPY_CONFIG_FILE_DIR/../../Misc/mypy
+explicit_package_bases = True
+python_version = 3.13
+platform = linux
+pretty = True
+
+# ... Enable most stricter settings
+enable_error_code = ignore-without-code,redundant-expr
+strict = True
+
+# can't enable before glob isn't typed ...
+warn_return_any = False
+disable_error_code = attr-defined
+
+# Various stricter settings that we can't yet enable
+# Try to enable these in the following order:
+disallow_untyped_calls = False
+disallow_untyped_defs = False
+check_untyped_defs = False