https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92495
Arthur O'Dwyer <arthur.j.odwyer at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |arthur.j.odwyer at gmail dot com --- Comment #2 from Arthur O'Dwyer <arthur.j.odwyer at gmail dot com> --- FWIW, my understanding is that the current failure-to-compile is correct: GCC is implementing P1907 which requires all data members to be public (and does *not* any longer require operator<=> to be defined) in order for you to use a user-defined type as a NTTP. Wilhelm's code was valid circa N4835, but is not supposed to be valid post-P1907.