https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70936
--- Comment #2 from lh_mouse <lh_mouse at 126 dot com> --- (In reply to Andrew Pinski from comment #1) > I use relocatable directory feature on Linux but I have not tested 6 yet. > This is a driver issue I think ... I was examining gcc/gcc/incpath.c for problems, though failed to find any, I think it is worthing mentioning that '-iprefix this_directory_need_not_exist/' effectively vanished the problem - that is, the order of C and C++ include paths became correct again.