https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71386
--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> --- Slightly simpler template<class...XS> auto List(XS...xs) { return [=](auto processList){return processList(xs...);}; }; auto l1 = List(42); auto foo = [](auto... xs1) { return [=]() { return l1([=](auto) { return __builtin_printf("%d",xs1...); }); }; }; int main() { auto concat = l1(foo); concat(); __builtin_printf("\n"); } If I make xs1 non-variadic (just erase '...' in 2 places), things work. The main difference seems to be in <lambda(auto:2 ...)> [with auto:2 = {int}] (we write to some place in the stack then re-read the value from another place) but it isn't clear what is going wrong there.