https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86634
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> --- GCC doesn't accept this, presumably because your test is incomplete: 86634.cc:2:5: error: 'Convertible' does not name a type 2 | Convertible<typename ForwardIterator::iterator_category> a; | ^~~~~~~~~~~ 86634.cc:3:31: error: expected unqualified-id before '...' token 3 | class iterator_category { ... }; // or maybe a typedef | ^~~ In any case, compilers are not required to diagnose problems in uninstantiated templates.