Godbolt

template<typename T>structx;template<typename T>constexprint y = x::a;// Clang diagnostic doesn't mention that `x` is a template.using z = x;// Clang diagnostic mentions that `x` is a template.

In the definition ofy, Clang complains thatx isn't a "class, namespace, or enumeration", but fails to mention that it is a class template and no template parameters have been provided.

In other simpler contexts, such as the definition of the using aliasy, Clang does explain thatx is a class template and template parameters need to be provided.

We should improve the quality of the diagnostic for they case - it should explain thatx is a class template and template parameters are missing.