[Bug c++/109997] __is_assignable(int, IncompleteType) should be rejected

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109997

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org
   Last reconfirmed|                            |2023-05-26
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Same for std::is_constructible.  So presumably we want something like

--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -2173,7 +2173,10 @@ constructible_expr (tree to, tree from)
 static tree
 is_xible_helper (enum tree_code code, tree to, tree from, bool trivial)
 {
-  to = complete_type (to);
+  to = complete_type_or_else (to, NULL_TREE);
+  from = complete_type_or_else (from, NULL_TREE);
+  if (!from || !to)
+    return error_mark_node;
   deferring_access_check_sentinel acs (dk_no_deferred);
   if (VOID_TYPE_P (to) || ABSTRACT_CLASS_TYPE_P (to)
       || (from && FUNC_OR_METHOD_TYPE_P (from)

but I'd have to test std::is_constructible with a parameter pack as well.