http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60976
--- Comment #4 from Chernyshev Viacheslav <astellar at ro dot ru> --- After a series of tests I'm pretty sure that it is not a problem of g++, but libstdc++. Let me explain why do I think so. First, I was not able to reduce real life case to reasonably small subset that does not depend on external libs at least. So I've decided to test explicit template instantiation of std::map for multiple combination of integer types as key and value. File that I've used is attached as test.cpp. Overall pattern was the same. After that I realized that results depend on actual libstdc++ includes and I compare apples with oranges. So, I've used these commands to get preprocessed dump: - g++-4.8 -std=gnu++11 -O0 -E -P std_map.cpp > preprocessed_48.cpp - g++-4.9 -std=gnu++11 -O0 -E -P std_map.cpp > preprocessed_49.cpp After that I've compiled both files with g++-4.8 first and g++-4.9 second to compare results. And it turned out that they are nearly the same for both compilers depending on what file I compile. ftime-reports are in attachments. I understand that it is not a bug per se, but compilation time for my project that uses STL containers a lot jumped from 15 minutes to 40 minutes mark, and it would be nice to reduce it back somehow.
