https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52130
Eric Gallager <egallager at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |WAITING Last reconfirmed| |2017-08-18 CC| |egallager at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Eric Gallager <egallager at gcc dot gnu.org> --- You can make g++ reject it with -pedantic-errors: $ /usr/local/bin/g++ -c -Wall -Wextra -pedantic-errors -std=c++11 52130.cc 52130.cc:2:27: error: ‘enum S<T>::E’ is an enumeration template [-Wpedantic] template<typename T> enum S<T>::E : T { e }; ^~~~ $ Is that sufficient?