https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106472
--- Comment #21 from Jeff Rahr <jeffrey.rahr at baesystems dot com> --- Roger - I was getting that same error when building out of the box for langueages=c,c++,fortran,lto,jit,go,d (ie didn't edit Makefile.def). Based on https://forum.dlang.org/post/qgrchukzyceflenrr...@forum.dlang.org that said on some platforms libphobos is not enabled by default, I added --enable-libphobos to my configure and my build worked after that.