https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67491 Bug 67491 depends on bug 99968, which changed state.
Bug 99968 Summary: ICE on remove_const_t<incomplete enum type> in requires-expression https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99968 What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution|--- |FIXED