Make several fields read-only for type, staticmethod and classmethod (#7423)

stdlib/builtins.pyi

@@ -115,8 +115,10 @@ class object:
     def __init_subclass__(cls) -> None: ...
 
 class staticmethod(Generic[_R_co]):
-    __func__: Callable[..., _R_co]
-    __isabstractmethod__: bool
+    @property
+    def __func__(self) -> Callable[..., _R_co]: ...
+    @property
+    def __isabstractmethod__(self) -> bool: ...
     def __init__(self: staticmethod[_R_co], __f: Callable[..., _R_co]) -> None: ...
     def __get__(self, __obj: _T, __type: type[_T] | None = ...) -> Callable[..., _R_co]: ...
     if sys.version_info >= (3, 10):
@@ -126,8 +128,10 @@ class staticmethod(Generic[_R_co]):
         def __call__(self, *args: Any, **kwargs: Any) -> _R_co: ...
 
 class classmethod(Generic[_R_co]):
-    __func__: Callable[..., _R_co]
-    __isabstractmethod__: bool
+    @property
+    def __func__(self) -> Callable[..., _R_co]: ...
+    @property
+    def __isabstractmethod__(self) -> bool: ...
     def __init__(self: classmethod[_R_co], __f: Callable[..., _R_co]) -> None: ...
     def __get__(self, __obj: _T, __type: type[_T] | None = ...) -> Callable[..., _R_co]: ...
     if sys.version_info >= (3, 10):
@@ -136,19 +140,28 @@ class classmethod(Generic[_R_co]):
         __wrapped__: Callable[..., _R_co]
 
 class type:
-    __base__: type
+    @property
+    def __base__(self) -> type: ...
     __bases__: tuple[type, ...]
-    __basicsize__: int
-    __dict__: dict[str, Any]
-    __dictoffset__: int
-    __flags__: int
-    __itemsize__: int
+    @property
+    def __basicsize__(self) -> int: ...
+    @property
+    def __dict__(self) -> types.MappingProxyType[str, Any]: ...  # type: ignore[override]
+    @property
+    def __dictoffset__(self) -> int: ...
+    @property
+    def __flags__(self) -> int: ...
+    @property
+    def __itemsize__(self) -> int: ...
     __module__: str
-    __mro__: tuple[type, ...]
+    @property
+    def __mro__(self) -> tuple[type, ...]: ...
     __name__: str
     __qualname__: str
-    __text_signature__: str | None
-    __weakrefoffset__: int
+    @property
+    def __text_signature__(self) -> str | None: ...
+    @property
+    def __weakrefoffset__(self) -> int: ...
     @overload
     def __init__(self, __o: object) -> None: ...
     @overload