Fix tuple subtyping

Fix needed for https://github.com/python/mypy/pull/16053/files#r1316481395

Author: hauntsaninja

mypy/subtypes.py

@@ -435,8 +435,11 @@ def visit_instance(self, left: Instance) -> bool:
             # dynamic base classes correctly, see #5456.
             return not isinstance(self.right, NoneType)
         right = self.right
-        if isinstance(right, TupleType) and right.partial_fallback.type.is_enum:
-            return self._is_subtype(left, mypy.typeops.tuple_fallback(right))
+        if isinstance(right, TupleType):
+            return (
+                self._is_subtype(left, right.partial_fallback)
+                and self._is_subtype(left, mypy.typeops.tuple_fallback(right))
+            )
         if isinstance(right, Instance):
             if type_state.is_cached_subtype_check(self._subtype_kind, left, right):
                 return True

test-data/unit/check-tuples.test

@@ -113,7 +113,7 @@ t1: Tuple[A, A]
 t2: tuple
 
 if int():
-    t1 = t2 # E: Incompatible types in assignment (expression has type "Tuple[Any, ...]", variable has type "Tuple[A, A]")
+    t1 = t2
 if int():
     t2 = t1
 

test-data/unit/check-typevar-tuple.test

@@ -61,8 +61,7 @@ f(empty)  # E: Argument 1 to "f" has incompatible type "Tuple[()]"; expected "Tu
 f(bad_args)  # E: Argument 1 to "f" has incompatible type "Tuple[str, str]"; expected "Tuple[int, str]"
 
 # The reason for error in subtle: actual can be empty, formal cannot.
-reveal_type(f(var_len_tuple))  # N: Revealed type is "Tuple[builtins.str, Unpack[builtins.tuple[builtins.int, ...]]]" \
-                               # E: Argument 1 to "f" has incompatible type "Tuple[int, ...]"; expected "Tuple[int, Unpack[Tuple[int, ...]]]"
+reveal_type(f(var_len_tuple))  # N: Revealed type is "Tuple[builtins.str, Unpack[builtins.tuple[builtins.int, ...]]]"
 
 g_args: Tuple[str, int]
 reveal_type(g(g_args))  # N: Revealed type is "Tuple[builtins.str, builtins.str]"