https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63234 --- Comment #5 from baoshan <pangbw at gmail dot com> --- I dig it deeper yesterday, and I believe this change makes the 5.0 works fine: https://github.com/gcc-mirror/gcc/commit/9b59e2174ee59dd3aa55c7c3342daa2a6bc23fba