Add type hints for with_appcontext decorator

CHANGES.rst

@@ -95,6 +95,8 @@ Unreleased
     functions. :pr:`4695`
 -   It is now possible to also call ``@with_appcontext`` decorator
     with parenthesis, to have additional parity with Quart.
+-   The ``@with_appcontext`` decorator decorator has type hints.
+
 
 Version 2.1.3
 -------------

src/flask/cli.py

@@ -408,7 +408,7 @@ class ScriptInfo:
 pass_script_info = click.make_pass_decorator(ScriptInfo, ensure=True)
 
 
-def with_appcontext(f=None):
+def with_appcontext(f: t.Optional[t.Callable] = None) -> t.Callable:
     """Wraps a callback so that it's guaranteed to be executed with the
     script's application context.