Only add note if we see .setter or .deleter

Author: sterliakov

mypy/semanal.py

@@ -7159,12 +7159,20 @@ def already_defined(
         )
 
         if (
-            isinstance(ctx, (OverloadedFuncDef, Decorator))
+            self.maybe_property_setter_or_deleter(ctx)
             and node is not None
             and self.maybe_property_definition(node)
         ):
             self.note("Property setter and deleter must be adjacent to the getter.", ctx)
 
+    def maybe_property_setter_or_deleter(self, node: SymbolNode) -> bool:
+        if isinstance(node, OverloadedFuncDef) and node.unanalyzed_items:
+            node = node.unanalyzed_items[0]
+        return isinstance(node, Decorator) and any(
+            isinstance(dec, MemberExpr) and dec.name in ("setter", "deleter")
+            for dec in node.decorators
+        )
+
     def maybe_property_definition(self, node: SymbolNode) -> bool:
         if isinstance(node, Decorator) and node.func.is_property:
             return True

test-data/unit/check-classes.test

@@ -1919,6 +1919,109 @@ class E:
     def val(self): ...
 
     reveal_type(val)  # N: Revealed type is "builtins.property"
+
+class F:
+    @property
+    def val(self): ...
+
+    reveal_type(val)  # N: Revealed type is "builtins.property"
+    def _other(self) -> None: ...
+
+    @val.setter  # E: Name "val" already defined on line 78 \
+                 # N: Property setter and deleter must be adjacent to the getter.
+    def val(self, val): ...
+
+    reveal_type(val)  # N: Revealed type is "builtins.property"
+    def _other2(self) -> None: ...
+
+    @val.deleter  # E: Name "val" already defined on line 78 \
+                  # N: Property setter and deleter must be adjacent to the getter.
+    def val(self): ...
+
+    reveal_type(val)  # N: Revealed type is "builtins.property"
+[builtins fixtures/property-full.pyi]
+
+[case testPropertyRedefinition]
+class A1:
+    @property
+    def fn(self) -> None: ...
+
+    @property  # E: Only supported top decorator is @fn.setter
+    def fn(self) -> None: ...
+
+class B1:
+    @property
+    def fn(self) -> None: ...
+
+    def foo(self) -> None: ...
+
+    @property  # E: Name "fn" already defined on line 9
+    def fn(self) -> None: ...
+
+class A2:
+    @property
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+    @property  # E: Only supported top decorator is @fn.setter
+    def fn(self) -> None: ...
+
+class B2:
+    @property
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+    def foo(self) -> None: ...
+
+    @property  # E: Name "fn" already defined on line 27
+    def fn(self) -> None: ...
+
+class A3:
+    @property
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+    @property  # E: Only supported top decorator is @fn.setter
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+class B3:
+    @property
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+    def foo(self) -> None: ...
+
+    @property  # E: Name "fn" already defined on line 49
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+class A4:
+    @property
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+class B4:
+    @property
+    def fn(self) -> None: ...
+    @fn.setter
+    def fn(self, _: None) -> None: ...
+
+    def foo(self) -> None: ...
+
+    @fn.setter  # E: Name "fn" already defined on line 71 \
+                # N: Property setter and deleter must be adjacent to the getter.
+    def fn(self, _: None) -> None: ...
 [builtins fixtures/property-full.pyi]
 
 -- Descriptors