Created attachment 490232 [details] build log See attached log.
Created attachment 490352 [details] emerge --info output
Created attachment 490354 [details] output For me looks fine: ================================================================= Package Settings ================================================================= sys-libs/glibc-2.26::gentoo was built with the following: USE="(multilib) rpc -audit -caps -debug -gd (-hardened) -nscd -profile (-selinux) -suid -systemtap -vanilla" ABI_X86="(64)" CFLAGS="-march=native -pipe -O2 -fno-strict-aliasing" CXXFLAGS="-march=native -pipe -O2 -fno-strict-aliasing"
Looks like gcc-6.4.0 not compiled with this version of glibc. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81710
GCC-7.2 working fine.
*** This bug has been marked as a duplicate of bug 589370 ***