https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81966
--- Comment #3 from Ian Lance Taylor <ian at airs dot com> --- The patch is to a file in gcc/go/gofrontend, not to a file in libgo. You probably can not simply copy the gcc/go directory from trunk to GCC 7, as it will expect other changes. But you can apply the patch itself, which is small, to gcc/go/gofrontend/types.cc.
