Fix typing

Author: cdce8p

mypy/applytype.py

@@ -147,7 +147,18 @@ def apply_generic_arguments(
     # TODO: move apply_poly() logic from checkexpr.py here when new inference
     # becomes universally used (i.e. in all passes + in unification).
     # With this new logic we can actually *add* some new free variables.
-    remaining_tvars = [expand_type(tv, id_to_type) for tv in tvars if tv.id not in id_to_type]
+    remaining_tvars: list[TypeVarLikeType] = []
+    for tv in tvars:
+        if tv.id in id_to_type:
+            continue
+        if not tv.has_default():
+            remaining_tvars.append(tv)
+            continue
+        # TypeVarLike isn't in id_to_type mapping.
+        # Only expand the TypeVar default here.
+        typ = expand_type(tv, id_to_type)
+        assert isinstance(typ, TypeVarLikeType)
+        remaining_tvars.append(typ)
 
     return callable.copy_modified(
         ret_type=expand_type(callable.ret_type, id_to_type),

mypy/semanal.py

@@ -1954,13 +1954,14 @@ class Foo(Bar, Generic[T]): ...
             del base_type_exprs[i]
         tvar_defs: list[TypeVarLikeType] = []
         for name, tvar_expr in declared_tvars:
-            if isinstance(tvar_expr.default, UnboundType):
+            tvar_expr_default = tvar_expr.default
+            if isinstance(tvar_expr_default, UnboundType):
                 # Assumption here is that the names cannot be duplicated
                 # TODO: - detect out of order and self-referencing typevars
                 #       - nested default types, e.g. list[T1]
                 for fullname, type_var in self.tvar_scope.scope.items():
                     type_var_name = fullname.rpartition(".")[2]
-                    if tvar_expr.default.name == type_var_name:
+                    if tvar_expr_default.name == type_var_name:
                         tvar_expr.default = type_var
             tvar_def = self.tvar_scope.bind_new(name, tvar_expr)
             tvar_defs.append(tvar_def)