https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84056
--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to Alper Ce from comment #3) > I didn't assign anything to my_map(i didn't use assignment operator = ), i > just used == operator to check value of it. Again, did you read the doc for operator[]? For instance http://en.cppreference.com/w/cpp/container/map/operator_at