https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67515
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- 12.6.2 [class.base.init] p16 says this is undefined (and has a very similar example).