https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82218
--- Comment #1 from Emil Fresk <emil.fresk at gmail dot com> --- Moreover, if one changes so Params... type-pack is not void it also compiles fine. The use of void seems to be the part causing the problem. This can be tested by changing void(void) to void(int) on line 134, and adding an argument to a(), on line 138, for example a(10).