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

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

[redi at gcc dot gnu.org]

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

            Bug ID: 109997
           Summary: __is_assignable(int, IncompleteType) should be
                    rejected
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
            Blocks: 71579
  Target Milestone: ---

struct S;
bool b = __is_assignable(int, S);

This should be rejected:

The precondition for std::is_assignable is:

"T and U shall be complete types, cv void, or arrays of unknown bound."


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71579
[Bug 71579] type_traits miss checks for type completeness in some traits

[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.

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

[pinskia at gcc dot gnu.org]

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

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=92067

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Isn't this a dup of bug 92067?

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

[pinskia at gcc dot gnu.org]

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

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> Isn't this a dup of bug 92067?

Sorry I mean is_constructible is recorded as PR 92067. I was reading some other
bug headline and getting confused.

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

[redi at gcc dot gnu.org]

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

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Looks pretty similar, although I don't think we even had __is_assignable when
that was filed.