https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70820
--- Comment #5 from Fabio Rocha <fdrocha at gmail dot com> --- (In reply to Jonathan Wakely from comment #4) > (In reply to Fabio Rocha from comment #3) > > Still, it feels pretty strange that uncommenting the "First Assert" is what > > makes the code incorrect... > > That's not strange at all, the assertion requires the value of the static > data member, so it causes it to be instantiated, while the type is > incomplete. > > Without that assertion the static data member is not instantiated until the > definition of ::k, after the types are complete. That makes sense, it's pretty nice that it works out like this. For what it's worth, clang rejects the code, but I am convinced gcc is in the right.
