Detect more decorated properties

Author: JukkaL

mypy/semanal.py

@@ -303,6 +303,8 @@ def analyse_property_with_multi_part_definition(self, defn: OverloadedFuncDef) -
                     if node.name == 'setter':
                         # The first item represents the entire property.
                         defn.items[0].var.is_settable_property = True
+            else:
+                self.fail("Decorated property not supported", item)
             item.func.accept(self)
 
     def analyse_function(self, defn: FuncItem) -> None:

mypy/test/data/semanal-errors.test

@@ -1251,7 +1251,7 @@ class A:
     @overload  # E: Decorated property not supported
     @property
     def f(self) -> int: pass
-    @property
+    @property  # E: Decorated property not supported
     @overload
     def f(self) -> int: pass
 [builtins fixtures/property.py]