https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66758
--- Comment #1 from Eric Niebler <eric.niebler at gmail dot com> --- Created attachment 35907 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35907&action=edit preprocessed source, bug #2(?) This might be the same bug, but the error is different. It yields: /cygdrive/c/Users/eric/Code/cmcstl2/include/stl2/concepts/foundational.hpp:33:27: internal compiler error: in tsubst_pack_expansion, at cp/pt.c:10578 T{ stl2::forward<Args>(args)... }; ^
