Fix crash on joins with recursive tuples

mypy/typeops.py

@@ -76,12 +76,18 @@ def is_recursive_pair(s: Type, t: Type) -> bool:
             isinstance(get_proper_type(t), (Instance, UnionType))
             or isinstance(t, TypeAliasType)
             and t.is_recursive
+            # Tuple types are special, they can cause an infinite recursion even if
+            # the other type is not recursive, because of the tuple fallback that is
+            # calculated "on the fly".
+            or isinstance(get_proper_type(s), TupleType)
         )
     if isinstance(t, TypeAliasType) and t.is_recursive:
         return (
             isinstance(get_proper_type(s), (Instance, UnionType))
             or isinstance(s, TypeAliasType)
             and s.is_recursive
+            # Same as above.
+            or isinstance(get_proper_type(t), TupleType)
         )
     return False
 

test-data/unit/check-recursive-types.test

@@ -937,3 +937,12 @@ x: A[int, str]
 if last is not None:
     reveal_type(last)  # N: Revealed type is "Tuple[builtins.int, builtins.str, Union[Tuple[builtins.int, builtins.str, Union[..., None]], None]]"
 [builtins fixtures/tuple.pyi]
+
+[case testRecursiveAliasLiteral]
+from typing import Tuple
+from typing_extensions import Literal
+
+NotFilter = Tuple[Literal["not"], "NotFilter"]
+n: NotFilter
+reveal_type(n[1][1][0])  # N: Revealed type is "Literal['not']"
+[builtins fixtures/tuple.pyi]