[Bug c++/91844] New: Implement CWG 2352, Similar types and reference binding

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91844

            Bug ID: 91844
           Summary: Implement CWG 2352, Similar types and reference
                    binding
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mpolacek at gcc dot gnu.org
  Target Milestone: ---

int *ptr;

const int *const &
f()
{
  return ptr;
}

Here, a reference to a temporary is returned, because under the old wording,
"int *" and "const int * const" are not reference-related, because they're not
the same types.  But this CWG changed the definition of "reference-related" to
say

“cv1 T1” is reference-related to “cv2 T2” if T1 is similar ([conv.qual]) to T2,
or T1 is a base class of T2.
http://eel.is/c++draft/dcl.init#def:reference-related

So it seems we need to tweak reference_related_p, and then we will bind
directly to ptr.