Support {typing,typing_extensions}.override

Summary:
THe `typing_extensions.override` was added a few months ago,
we should support it.

The `typing.override` decorator isn't landed yet, but that's okay - we
should support it in override checks; it will still raise a "no such name"
method when Pyre is being run against a typeshed that doens't have it yet.

The PR to add `typing.override` to CPython is out for review now:
https://github.com/python/cpython/pull/101564`

Reviewed By: grievejia

Differential Revision: D43055550

fbshipit-source-id: 3f51f643063afea75bf54ef38ae3a48681b99bd9

Author: stroxler

source/analysis/test/integration/methodTest.ml

@@ -2610,7 +2610,7 @@ let test_check_override_decorator context =
   let assert_type_errors = assert_type_errors ~context in
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      class Foo:
        def different_method(self, input: int) -> int:
@@ -2627,7 +2627,7 @@ let test_check_override_decorator context =
     ];
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      class Foo:
        @staticmethod
@@ -2645,7 +2645,7 @@ let test_check_override_decorator context =
     ];
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      class Foo:
        @classmethod
@@ -2660,7 +2660,7 @@ let test_check_override_decorator context =
     [];
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      @override
      def foo(input: int) -> int:
@@ -2672,7 +2672,7 @@ let test_check_override_decorator context =
     ];
   assert_type_errors
     {|
-      from pyre_extensions import override
+      from typing import override
 
       def foo_outer(input: int) -> int:
         @override
@@ -2688,7 +2688,7 @@ let test_check_override_decorator context =
     ];
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      class Foo1:
        def foo(self, input: int) -> int:
@@ -2704,7 +2704,7 @@ let test_check_override_decorator context =
     [];
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      class Foo:
        def foo(self, input: int) -> str:
@@ -2719,7 +2719,7 @@ let test_check_override_decorator context =
          needs to be checked. *) ];
   assert_type_errors
     {|
-     from pyre_extensions import override
+     from typing import override
 
      class Foo:
        foo: int = 3
@@ -2729,6 +2729,24 @@ let test_check_override_decorator context =
        foo: str = "hello world"
     |}
     ["Parsing failure [404]: invalid syntax"];
+  assert_type_errors
+    {|
+     import typing_extensions
+     import pyre_extensions
+
+     class Bar:
+       @pyre_extensions.override
+       def method0(self) -> None: ...
+
+       @pyre_extensions.override
+       def method1(self) -> None: ...
+    |}
+    [
+      "Invalid override [40]: `test.Bar.method0` is decorated with @override, but no method of the \
+       same name exists in superclasses of `Bar`.";
+      "Invalid override [40]: `test.Bar.method1` is decorated with @override, but no method of the \
+       same name exists in superclasses of `Bar`.";
+    ];
   ()
 
 

source/ast/statement.ml

@@ -665,7 +665,11 @@ end = struct
 
     let is_final_method signature = has_decorator signature "typing.final"
 
-    let is_override_method signature = has_decorator signature "pyre_extensions.override"
+    let is_override_method signature =
+      has_decorator signature "typing.override"
+      || has_decorator signature "typing_extensions.override"
+      || has_decorator signature "pyre_extensions.override"
+
 
     let is_dunder_method signature =
       let name = unqualified_name signature in

source/test/test.ml

@@ -1080,6 +1080,7 @@ let typeshed_stubs ?(include_helper_builtins = true) () =
           Literal: _SpecialForm = ...
           # TypedDict is a (non-subscriptable) special form.
           TypedDict: object
+          def override(f: _F) -> _F: ...
 
         Callable: _SpecialForm = ...
         Protocol: _SpecialForm = ...
@@ -1482,7 +1483,13 @@ let typeshed_stubs ?(include_helper_builtins = true) () =
         |};
     ( "typing_extensions.pyi",
       {|
-        from typing import Final as Final, ParamSpec as ParamSpec, _SpecialForm, overload as overload
+        from typing import (
+          _SpecialForm,
+          Final as Final,
+          ParamSpec as ParamSpec,
+          overload as overload,
+          override as override
+        )
         Literal: _SpecialForm = ...
         LiteralString: _SpecialForm = ...