https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80858
--- Comment #2 from sgunderson at bigfoot dot com --- Yes, I mean that the error message isn't clear (and it's basically the same error message in 4.8, so no regression). I don't think I understand the difficulties involved. Doesn't the error come as a direct result of my copying? If I do this with e.g. std::vector, I get a much clearer error message, which directly points to the line in question: […] /usr/include/c++/6/bits/vector.tcc:195:19: required from ‘std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = std::unique_ptr<int>; _Alloc = std::all ocator<std::unique_ptr<int> >]’ test.cc:7:7: required from here My main gripe is that with unordered_map, the error traceback stops in the internal details of _Hashtable: /usr/include/c++/7/bits/unordered_map.h:101:11: required from here In the real-world case in question, I eventually had to go into unordered_map.h (yes, in /usr/include) and replace “= default;” with “= delete;” to figure out who was calling the copy constructor.
