https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68071
Bug ID: 68071 Summary: Generic lambda variadic argument pack cannot be empty Product: gcc Version: 5.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: vittorio.romeo at outlook dot com Target Milestone: --- struct C { template<typename T, typename... TRest> auto operator()(T&& x, TRest&&...){ return x; } }; int main() { // Compiles both with clang and gcc. auto c = C{}; c(1); // Compiles with clang 3.7. // Does not compile with gcc 5.2. auto l = [](auto&& x, auto&&...) { return x; }; l(1); } decltype(l)::operator() should be equivalent to C::operator(), but if variadic pack is left empty in the generic lambda, gcc refuses to compile: 15 : error: no match for call to '(main()::) (int)' l(1); 15 : note: candidate: decltype (((main()::)0u).main()::(x, )) (*)(auto:1&&, auto:2&&, ...) 15 : note: candidate expects 3 arguments, 2 provided 14 : note: candidate: template main():: auto l = [](auto&& x, auto&&...) { return x; }; 14 : note: template argument deduction/substitution failed: 15 : note: candidate expects 2 arguments, 1 provided l(1); Live example on godbolt.org: https://goo.gl/2ikAUK