stubtest: special case final and deprecated (#16457)

We should probably lean into the type checker harder here

Fixes #14950
Fixes
python/typeshed#11009 (comment)

Author: hauntsaninja

mypy/stubtest.py

@@ -1215,6 +1215,12 @@ def _resolve_funcitem_from_decorator(dec: nodes.OverloadPart) -> nodes.FuncItem
     def apply_decorator_to_funcitem(
         decorator: nodes.Expression, func: nodes.FuncItem
     ) -> nodes.FuncItem | None:
+        if (
+            isinstance(decorator, nodes.CallExpr)
+            and isinstance(decorator.callee, nodes.RefExpr)
+            and decorator.callee.fullname in mypy.types.DEPRECATED_TYPE_NAMES
+        ):
+            return func
         if not isinstance(decorator, nodes.RefExpr):
             return None
         if not decorator.fullname:
@@ -1223,6 +1229,7 @@ def apply_decorator_to_funcitem(
         if (
             decorator.fullname in ("builtins.staticmethod", "abc.abstractmethod")
             or decorator.fullname in mypy.types.OVERLOAD_NAMES
+            or decorator.fullname in mypy.types.FINAL_DECORATOR_NAMES
         ):
             return func
         if decorator.fullname == "builtins.classmethod":

mypy/test/teststubtest.py

@@ -71,6 +71,8 @@ class Sequence(Iterable[_T_co]): ...
 class Tuple(Sequence[_T_co]): ...
 class NamedTuple(tuple[Any, ...]): ...
 def overload(func: _T) -> _T: ...
+def deprecated(__msg: str) -> Callable[[_T], _T]: ...
+def final(func: _T) -> _T: ...
 """
 
 stubtest_builtins_stub = """
@@ -630,6 +632,23 @@ def f5(__b: str) -> str: ...
             runtime="def f5(x, /): pass",
             error=None,
         )
+        yield Case(
+            stub="""
+            from typing import deprecated, final
+            class Foo:
+                @overload
+                @final
+                def f6(self, __a: int) -> int: ...
+                @overload
+                @deprecated("evil")
+                def f6(self, __b: str) -> str: ...
+            """,
+            runtime="""
+            class Foo:
+                def f6(self, x, /): pass
+            """,
+            error=None,
+        )
 
     @collect_cases
     def test_property(self) -> Iterator[Case]:

mypy/types.py

@@ -119,6 +119,9 @@
 # Supported Annotated type names.
 ANNOTATED_TYPE_NAMES: Final = ("typing.Annotated", "typing_extensions.Annotated")
 
+# Supported @deprecated type names
+DEPRECATED_TYPE_NAMES: Final = ("typing.deprecated", "typing_extensions.deprecated")
+
 # We use this constant in various places when checking `tuple` subtyping:
 TUPLE_LIKE_INSTANCE_NAMES: Final = (
     "builtins.tuple",