https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70820
--- Comment #3 from Fabio Rocha <fdrocha at gmail dot com> --- (In reply to Jason Merrill from comment #1) > 14.7.1: "The implicit instantiation of a class template specialization > causes the implicit instantiation of the declarations, but not of the > definitions, default arguments, or exception-specifications of the class > member functions, member classes, scoped member enumerations, static data > members and member templates; and it causes the implicit instantiation of > the definitions of unscoped member enumerations and member anonymous unions." > > So I don't think that the instantiation of Base<Derived> requires the > instantiation of the definition of Base<Derived>::i. You may be correct, not sure this is actually bug. Still, it feels pretty strange that uncommenting the "First Assert" is what makes the code incorrect...
