Fix override checking for decorated property (#16856)

Fixes #16855

Author: hauntsaninja

mypy/checker.py

@@ -2020,22 +2020,29 @@ def check_method_override_for_base_with_name(
                 if original_node and is_property(original_node):
                     original_type = get_property_type(original_type)
 
-            if isinstance(typ, FunctionLike) and is_property(defn):
-                typ = get_property_type(typ)
-                if (
-                    isinstance(original_node, Var)
-                    and not original_node.is_final
-                    and (not original_node.is_property or original_node.is_settable_property)
-                    and isinstance(defn, Decorator)
-                ):
-                    # We only give an error where no other similar errors will be given.
-                    if not isinstance(original_type, AnyType):
-                        self.msg.fail(
-                            "Cannot override writeable attribute with read-only property",
-                            # Give an error on function line to match old behaviour.
-                            defn.func,
-                            code=codes.OVERRIDE,
-                        )
+            if is_property(defn):
+                inner: FunctionLike | None
+                if isinstance(typ, FunctionLike):
+                    inner = typ
+                else:
+                    inner = self.extract_callable_type(typ, context)
+                if inner is not None:
+                    typ = inner
+                    typ = get_property_type(typ)
+                    if (
+                        isinstance(original_node, Var)
+                        and not original_node.is_final
+                        and (not original_node.is_property or original_node.is_settable_property)
+                        and isinstance(defn, Decorator)
+                    ):
+                        # We only give an error where no other similar errors will be given.
+                        if not isinstance(original_type, AnyType):
+                            self.msg.fail(
+                                "Cannot override writeable attribute with read-only property",
+                                # Give an error on function line to match old behaviour.
+                                defn.func,
+                                code=codes.OVERRIDE,
+                            )
 
             if isinstance(original_type, AnyType) or isinstance(typ, AnyType):
                 pass

test-data/unit/check-functions.test

@@ -2730,6 +2730,49 @@ f: Callable[[Sequence[TI]], None]
 g: Callable[[Union[Sequence[TI], Sequence[TS]]], None]
 f = g
 
+[case testOverrideDecoratedProperty]
+class Base:
+    @property
+    def foo(self) -> int: ...
+
+class decorator:
+    def __init__(self, fn):
+        self.fn = fn
+    def __call__(self, decorated_self) -> int:
+        return self.fn(decorated_self)
+
+class Child(Base):
+    @property
+    @decorator
+    def foo(self) -> int:
+        return 42
+
+reveal_type(Child().foo)  # N: Revealed type is "builtins.int"
+
+class BadChild1(Base):
+    @decorator
+    def foo(self) -> int:  # E: Signature of "foo" incompatible with supertype "Base" \
+                           # N:      Superclass: \
+                           # N:          int \
+                           # N:      Subclass: \
+                           # N:          decorator
+        return 42
+
+class not_a_decorator:
+    def __init__(self, fn): ...
+
+class BadChild2(Base):
+    @property
+    @not_a_decorator
+    def foo(self) -> int:  # E: "not_a_decorator" not callable \
+                           # E: Signature of "foo" incompatible with supertype "Base" \
+                           # N:      Superclass: \
+                           # N:          int \
+                           # N:      Subclass: \
+                           # N:          not_a_decorator
+        return 42
+[builtins fixtures/property.pyi]
+
 [case explicitOverride]
 # flags: --python-version 3.12
 from typing import override