https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71261
--- Comment #1 from Uroš Bizjak <ubizjak at gmail dot com> --- It doesn't hang but takes some time to finish: $time ./cc1plus -std=c++11 -O3 -march=broadwell -quiet hang.cpp real 0m25.003s user 0m24.412s sys 0m0.275s