Always allow to cast to Any without warnings. (#8544)

Author: oda

mypy/checkexpr.py

@@ -3004,7 +3004,8 @@ def visit_cast_expr(self, expr: CastExpr) -> Type:
                                   allow_none_return=True, always_allow_any=True)
         target_type = expr.type
         options = self.chk.options
-        if options.warn_redundant_casts and is_same_type(source_type, target_type):
+        if (options.warn_redundant_casts and not isinstance(get_proper_type(target_type), AnyType)
+                and is_same_type(source_type, target_type)):
             self.msg.redundant_cast(target_type, expr)
         if options.disallow_any_unimported and has_any_from_unimported_type(target_type):
             self.msg.unimported_type_becomes_any("Target type of cast", target_type, expr)

test-data/unit/check-warnings.test

@@ -35,6 +35,12 @@ b = B()
 c = add([cast(A, b)], [a])
 [builtins fixtures/list.pyi]
 
+[case testCastToAnyTypeNotRedundant]
+# flags: --warn-redundant-casts
+from typing import cast, Any
+a: Any
+b = cast(Any, a)
+[builtins fixtures/list.pyi]
 
 -- Unused 'type: ignore' comments
 -- ------------------------------