https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67319
--- Comment #1 from Roland B <rbock at eudoxos dot de> --- Using the terse notation works fine, btw: // ----------------------------- template <typename T> concept bool Any() { return true; } struct my_struct { auto sample(Any... args) -> void; }; int main() { my_struct{}.sample(); } // -------------------------------