http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18610
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-09-21 14:48:34 UTC --- (In reply to comment #7) > (In reply to comment #6) > > N.B. that's even better than clang, as it tells you *why* substitution > > failed: > > the specialization Q<int> is incomplete > > Great! > > I agree it is better that it tells you *why*, but g++'s output is also > extremely verbose: 2 diagnostics versus 8, plus the repetition of > 'template<class T> F<typename Q<T>::t> g(const F<T>&)' and 'struct Q<int>'. > Moreover, the use of "note" and "error" is inconsistent. > > I would wish for something like: > > t.cc:17:9: error: no matching function for call to 'g' No, you need to know the argument types used for the call, not just the name of the function called. > t.cc:12:22: note: candidate template ignored: template argument > deduction/substitution failed [with T = int] Which candidate function? If there are several 'g' overloads you will get a note about each, I want them to be identified by more than the line they are declared on. > t.cc:12:22: note: reason: invalid use of incomplete type 'struct Q<int>' > t.cc:2:8: note: declared here This is just clang's output without the original source code snippets, which would definitely not be an improvement. > Current output will explode with large number of candidates and complex > template instantiations (e.g., STL stuff). But that is an old problem, in > general, and I guess hard to fix in g++. That's the whole point - it shows you *all* the candidates, why they were not viable, and the context that caused them to be instantiated - that's a Good Thing.
