https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79180
--- Comment #1 from Markus Dreseler <markus at dreseler dot de> --- P.S.: Also experienced on Wandbox's GCC 7.0.1 HEAD. Not passing the parameter pack into bar by universal reference causes an internal compiler error in gcc 7.0.1 HEAD: prog.cc: In function 'void bar(Args ...) [with Args = {std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >}]': prog.cc:14:4: internal compiler error: in make_decl_rtl, at varasm.c:1304 [&]() { ~~~~~~~ [&]() { ~~~~~~~ foo(args...); ~~~~~~~~~~~~~ }(); ~~~~ }(); ~^~ http://melpon.org/wandbox/permlink/mYtVweIn8zv4t74Y Thanks to AMA at StackOverflow for finding this.