[Bug c++/109337] New: c++2a test concepts4.C passes when it should fail

[cjdb.ns at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109337

            Bug ID: 109337
           Summary: c++2a test concepts4.C passes when it should fail
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: cjdb.ns at gmail dot com
  Target Milestone: ---

Clang and GCC disagree on the validity of concepts4.C. I think Clang is correct
here, because forming a reference to `void` should be ill-formed.

https://godbolt.org/z/es5GxYhzd