Gentoo's Bugzilla –
Attachment 490346 Details for
Bug 628756sys-libs/compiler-rt-sanitizers-4.0.1 with sys-libs/glibc-2.26 - …/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc:278:22: error: aggregate ‘sigaltstack handler_stack’ has incomplete type and cannot be defined