https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61814
Bug ID: 61814 Summary: [c++1y] cannot use decltype on captured arg-pack Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: tongari95 at gmail dot com The code below has a lambda that captures the outer params t, for forwarding matter, decltype on t has to be used. ``` auto const pack = [](auto&&... t) { return [&](auto&& f)->decltype(auto) { return f(static_cast<decltype(t)>(t)...); }; }; int main(int argc, char** argv) { pack(1)([](int){}); return 0; } ``` It works with clang 3.5, but g++ 4.9.0 complains: error: 't' was not declared in this scope The same also applies to `sizeof` or that kind of compile-time thing.