Fix redundant cast detection for generic calls

Author: Yoruxyv

mypy/checkexpr.py

@@ -4850,10 +4850,7 @@ def visit_enum_index_expr(
     def visit_cast_expr(self, expr: CastExpr) -> Type:
         """Type check a cast expression."""
         source_type = self.accept(
-            expr.expr,
-            type_context=AnyType(TypeOfAny.special_form),
-            allow_none_return=True,
-            always_allow_any=True,
+            expr.expr, type_context=None, allow_none_return=True, always_allow_any=True
         )
         target_type = expr.type
         options = self.chk.options

test-data/unit/check-warnings.test

@@ -12,6 +12,20 @@ c = cast(int, a)
 [out]
 main:5: error: Redundant cast to "int"
 
+[case testRedundantCastGenericReturn]
+# flags: --warn-redundant-casts
+from typing import TypeVar, cast
+
+T = TypeVar("T")
+
+def identity(xs: list[T]) -> list[T]:
+    return xs
+
+xs: list[int] = []
+cast(list[int], identity(xs))
+[out]
+main:10: error: Redundant cast to "list[int]"
+
 [case testRedundantCastWithIsinstance]
 # flags: --warn-redundant-casts
 from typing import cast, Union