Remove unnecessary casts in stubtest.py and types.py (#14856)

The `stubtest.py` cast is no longer needed -- I think the mypyc issue
was fixed by python/typeshed#9146.

The `types.py` casts were never needed. They were added relatively
recently by somebody called "Alex Waygood".

mypy/stubtest.py

@@ -25,7 +25,7 @@
 from contextlib import redirect_stderr, redirect_stdout
 from functools import singledispatch
 from pathlib import Path
-from typing import Any, Generic, Iterator, TypeVar, Union, cast
+from typing import Any, Generic, Iterator, TypeVar, Union
 from typing_extensions import get_origin
 
 import mypy.build
@@ -476,10 +476,7 @@ def verify_typeinfo(
     to_check = set(stub.names)
     # Check all public things on the runtime class
     to_check.update(
-        # cast to workaround mypyc complaints
-        m
-        for m in cast(Any, vars)(runtime)
-        if not is_probably_private(m) and m not in IGNORABLE_CLASS_DUNDERS
+        m for m in vars(runtime) if not is_probably_private(m) and m not in IGNORABLE_CLASS_DUNDERS
     )
     # Special-case the __init__ method for Protocols
     #

mypy/types.py

@@ -950,7 +950,8 @@ def __init__(
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         assert isinstance(visitor, SyntheticTypeVisitor)
-        return cast(T, visitor.visit_callable_argument(self))
+        ret: T = visitor.visit_callable_argument(self)
+        return ret
 
     def serialize(self) -> JsonDict:
         assert False, "Synthetic types don't serialize"
@@ -975,7 +976,8 @@ def __init__(self, items: list[Type], line: int = -1, column: int = -1) -> None:
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         assert isinstance(visitor, SyntheticTypeVisitor)
-        return cast(T, visitor.visit_type_list(self))
+        ret: T = visitor.visit_type_list(self)
+        return ret
 
     def serialize(self) -> JsonDict:
         assert False, "Synthetic types don't serialize"
@@ -2489,7 +2491,8 @@ def simple_name(self) -> str:
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         assert isinstance(visitor, SyntheticTypeVisitor)
-        return cast(T, visitor.visit_raw_expression_type(self))
+        ret: T = visitor.visit_raw_expression_type(self)
+        return ret
 
     def serialize(self) -> JsonDict:
         assert False, "Synthetic types don't serialize"
@@ -2736,7 +2739,8 @@ class EllipsisType(ProperType):
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         assert isinstance(visitor, SyntheticTypeVisitor)
-        return cast(T, visitor.visit_ellipsis_type(self))
+        ret: T = visitor.visit_ellipsis_type(self)
+        return ret
 
     def serialize(self) -> JsonDict:
         assert False, "Synthetic types don't serialize"
@@ -2845,7 +2849,8 @@ def __init__(self, fullname: str | None, args: list[Type], line: int) -> None:
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         assert isinstance(visitor, SyntheticTypeVisitor)
-        return cast(T, visitor.visit_placeholder_type(self))
+        ret: T = visitor.visit_placeholder_type(self)
+        return ret
 
     def __hash__(self) -> int:
         return hash((self.fullname, tuple(self.args)))