Genkernel 3.4.52.4 fails prepare on x86 for kernel 4.12.5. Reproducible: Always
Created attachment 488286 [details] genkernel.log
Duplicate, and neither of you have attached emerge --info output. Something is wrong with your GCC, it should have -fstack-protector support. *** This bug has been marked as a duplicate of bug 628576 ***