https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79396
--- Comment #8 from janus at gcc dot gnu.org --- (In reply to janus from comment #5) > Will check if enabling bootstrap solves the problem. Actually this does not seem to be the case. I still see the error with the following GCC build (on Ubuntu 16.10): Target: x86_64-linux-gnu Configured with: /home/janus/gcc/trunk/configure --program-suffix=-7 --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --enable-languages=c,c++,fortran --disable-multilib --with-arch=haswell Thread model: posix gcc version 7.0.1 20170212 (experimental) [trunk revision 245376] (GCC) Since no one can reproduce it, maybe it is Haswell-specific? I'll check if removing "--with-arch=haswell" helps ...