From 3a4298d16c660d5dec46cfa372b6aceb79c1e056 Mon Sep 17 00:00:00 2001
From: Nulano <nulano@nulano.eu>
Date: Wed, 27 Dec 2023 14:54:48 +0100
Subject: [PATCH] avoid hard dependency on typing_extensions

---
 docs/reference/internal_modules.rst | 13 +++++++++++++
 pyproject.toml                      |  6 +++---
 src/PIL/_typing.py                  | 16 ++++++++++++++++
 src/PIL/_util.py                    |  7 +------
 tox.ini                             |  2 ++
 5 files changed, 35 insertions(+), 9 deletions(-)
 create mode 100644 src/PIL/_typing.py

diff --git a/docs/reference/internal_modules.rst b/docs/reference/internal_modules.rst
index 363a67d9b..57dd3f35b 100644
--- a/docs/reference/internal_modules.rst
+++ b/docs/reference/internal_modules.rst
@@ -25,6 +25,19 @@ Internal Modules
     :undoc-members:
     :show-inheritance:
 
+:mod:`~PIL._typing` Module
+--------------------------
+
+.. module:: PIL._typing
+
+Provides a convenient way to import type hints that are not available
+on some supported Python versions.
+
+.. py:data:: TypeGuard
+    :value: typing.TypeGuard
+
+    See :py:obj:`typing.TypeGuard`.
+
 :mod:`~PIL._util` Module
 ------------------------
 
diff --git a/pyproject.toml b/pyproject.toml
index de707a283..abb32f14d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,9 +37,6 @@ classifiers = [
 dynamic = [
   "version",
 ]
-dependencies = [
-  'typing-extensions; python_version < "3.10"',
-]
 [project.optional-dependencies]
 docs = [
   "furo",
@@ -68,6 +65,9 @@ tests = [
   "pytest-cov",
   "pytest-timeout",
 ]
+typing = [
+  'typing-extensions; python_version < "3.10"',
+]
 xmp = [
   "defusedxml",
 ]
diff --git a/src/PIL/_typing.py b/src/PIL/_typing.py
new file mode 100644
index 000000000..583be41b7
--- /dev/null
+++ b/src/PIL/_typing.py
@@ -0,0 +1,16 @@
+import sys
+
+if sys.version_info >= (3, 10):
+    from typing import TypeGuard
+else:
+    try:
+        from typing_extensions import TypeGuard
+    except ImportError:
+        from typing import Any, Type
+
+        class TypeGuard:  # type: ignore[no-redef]
+            def __class_getitem__(cls, item: Any) -> Type[bool]:
+                return bool
+
+
+__all__ = ["TypeGuard"]
diff --git a/src/PIL/_util.py b/src/PIL/_util.py
index d11cbfa58..37cd979f6 100644
--- a/src/PIL/_util.py
+++ b/src/PIL/_util.py
@@ -1,14 +1,9 @@
 from __future__ import annotations
 
 import os
-import sys
 from pathlib import Path
 from typing import Any, NoReturn
-
-if sys.version_info >= (3, 10):
-    from typing import TypeGuard
-else:
-    from typing_extensions import TypeGuard
+from ._typing import TypeGuard
 
 
 def is_path(f: Any) -> TypeGuard[bytes | str | Path]:
diff --git a/tox.ini b/tox.ini
index 034d89372..bfcfaf5d9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -37,3 +37,5 @@ deps =
     numpy
 commands =
     mypy src {posargs}
+extras =
+    typing