Remove some hacks around using @overload (#7436)

Author: msullivan

mypy/fastparse.py

@@ -5,7 +5,7 @@
 from typing import (
     Tuple, Union, TypeVar, Callable, Sequence, Optional, Any, Dict, cast, List, overload
 )
-from typing_extensions import Final, Literal
+from typing_extensions import Final, Literal, overload
 
 from mypy.sharedparse import (
     special_function_elide_names, argument_elide_name,
@@ -127,18 +127,6 @@ def ast3_parse(source: Union[str, bytes], filename: str, mode: str,
 TYPE_IGNORE_PATTERN = re.compile(r'[^#]*#\s*type:\s*ignore\s*(\[[^[#]*\]\s*)?($|#)')
 
 
-# Older versions of typing don't allow using overload outside stubs,
-# so provide a dummy.
-# mypyc doesn't like function declarations nested in if statements
-def _overload(x: Any) -> Any:
-    return x
-
-
-# mypyc doesn't like unreachable code, so trick mypy into thinking the branch is reachable
-if bool() or sys.version_info < (3, 6):
-    overload = _overload  # noqa
-
-
 def parse(source: Union[str, bytes],
           fnam: str,
           module: Optional[str],

mypy/types.py

@@ -8,7 +8,7 @@
     Any, TypeVar, Dict, List, Tuple, cast, Set, Optional, Union, Iterable, NamedTuple,
     Sequence, Iterator, overload
 )
-from typing_extensions import ClassVar, Final, TYPE_CHECKING
+from typing_extensions import ClassVar, Final, TYPE_CHECKING, overload
 
 import mypy.nodes
 from mypy import state
@@ -21,17 +21,6 @@
 from mypy.bogus_type import Bogus
 
 
-# Older versions of typing don't allow using overload outside stubs,
-# so provide a dummy.
-# mypyc doesn't like function declarations nested in if statements
-def _overload(x: Any) -> Any:
-    return x
-
-
-# mypyc doesn't like unreachable code, so trick mypy into thinking the branch is reachable
-if bool() or sys.version_info < (3, 6):
-    overload = _overload  # noqa
-
 T = TypeVar('T')
 
 JsonDict = Dict[str, Any]