gcc/testsuite/g++.dg/cpp0x/variadic-ex13.C

   1 // { dg-do compile { target c++11 } }
   2
   3 template<typename T, typename U> struct is_same {
   4   static const bool value = false;
   5 };
   6
   7 template<typename T> struct is_same<T, T> {
   8   static const bool value = true;
   9 };
  10
  11 template<typename...> struct Tuple {};
  12 template<typename T1, typename T2> struct Pair {};
  13
  14 template<typename... Args1>
  15   struct zip {
  16     template<typename... Args2>
  17     struct with {
  18       typedef Tuple<Pair<Args1, Args2>...> type; // { dg-error "mismatched argument pack" }
  19     };
  20   };
  21
  22 static_assert
  23   (is_same<zip<short, int>::with<unsigned short, unsigned>::type,
  24            Tuple<Pair<short, unsigned short>, Pair<int, unsigned> > >::value,
  25    "zip");
  26
  27 typedef zip<short>::with<unsigned short, unsigned>::type T2; // error: different number of arguments specified
  28                                                              // for Args1 and Args2
  29
  30 template<typename... Args> void f(Args...);
  31
  32 template<typename... Args> void g(Args... args)
  33 {
  34    f(const_cast<const Args*>(&args)...); // okay: ``Args'' and ``args'' are expanded
  35    f(5 ...); // { dg-error "contains no argument packs" }
  36    f(args); // { dg-error "parameter packs not expanded" }
  37    // { dg-message "args" "note" { target *-*-* } 36 }
  38    f(h(args...) + args...); // okay: first ``args'' expanded within h, second ``args'' expanded within f.
  39 }