https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87880
--- Comment #8 from Iain Sandoe <iains at gcc dot gnu.org> --- I can see this on x86_64-darwin15 .. but not on darwin16, 17 or 18. please can you confirm that you definitely see this on darwin18? (and what your bootstrap compiler / config is). my tests were on 267418 with GCC5 as the bootstrap compiler on x86-64-darwin15 (for Ada support). On darwin16 it makes no difference if I use GCC or clang as the bootstrap compiler, on darwin17 and 18 I've only tried with clang as the bootstrap so far. Do you have SIP enabled, and did you install the target libs before running the tests?
