[Bug c++/121539] New: C style variadic ellipsis is incorrectly rejected after a default argument in a member function when not preceded by a comma

[luigighiron at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121539

            Bug ID: 121539
           Summary: C style variadic ellipsis is incorrectly rejected
                    after a default argument in a member function when not
                    preceded by a comma
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: luigighiron at gmail dot com
  Target Milestone: ---

The following program is incorrectly rejected by GCC:

struct S{
    void foo(int={}...){}
};

This program should be accepted, just like how it is accepted when using a
comma before the ellipsis. Only EDG accepts this program currently.