could it be related to flto?
Created attachment 518718 [details] emerge --info
Created attachment 518720 [details] build.log (middle truncated)
(In reply to Chris Chan from comment #2) > Created attachment 518720 [details] > build.log (middle truncated) Why truncated? The answer is usually to compress the file before uploading it.
libtool: link: x86_64-pc-linux-gnu-g++ -m32 -fvisibility=hidden -Werror=pointer-arith -Werror=vla -march=native -O3 -pipe -flto -Wall -fno-math-errno -fno-trapping-math -Wl,-O1 -Wl,--as-needed -o glsl_compiler glsl/main.o glsl/.libs/libstandalone.a -lz -lpthread -pthread /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/32/libstdc++.so: undefined reference to `pthread_create'
Created attachment 519408 [details] build log compressed
Yes, it's because of -flto. *** This bug has been marked as a duplicate of bug 641808 ***