[Bug c++/92171] New: accept incorrect access of static constexpr member when read from a reference

[jonathan.poelen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92171

            Bug ID: 92171
           Summary: accept incorrect access of static constexpr member
                    when read from a reference
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jonathan.poelen at gmail dot com
  Target Milestone: ---

#include <type_traits>

struct A
{
  static constexpr std::true_type value {};
};

int main()
{
  A a;
  A& ref = a;
  constexpr bool r1 = a.value; //ok
  constexpr bool r2 = ref.value; // this should not work
}

See https://bugs.llvm.org/show_bug.cgi?id=43732#c1