p9-0x.cpp revision a009b59fc2c550a229b9146aabda8e33fe3a7771
1// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s 2 3// Metafunction to extract the Nth type from a set of types. 4template<unsigned N, typename ...Types> struct get_nth_type; 5 6template<unsigned N, typename Head, typename ...Tail> 7struct get_nth_type<N, Head, Tail...> : get_nth_type<N-1, Tail...> { }; 8 9template<typename Head, typename ...Tail> 10struct get_nth_type<0, Head, Tail...> { 11 typedef Head type; 12}; 13 14// Placeholder type when get_nth_type fails. 15struct no_type {}; 16 17template<unsigned N> 18struct get_nth_type<N> { 19 typedef no_type type; 20}; 21 22template<typename ...Args> 23typename get_nth_type<0, Args...>::type first_arg(Args...); 24 25template<typename ...Args> 26typename get_nth_type<1, Args...>::type second_arg(Args...); 27 28// Test explicit specification of function template arguments. 29void test_explicit_spec_simple() { 30 int *ip1 = first_arg<int *>(0); 31 int *ip2 = first_arg<int *, float*>(0, 0); 32 float *fp1 = first_arg<float *, double*, int*>(0, 0, 0); 33} 34 35// Template argument deduction can extend the sequence of template 36// arguments corresponding to a template parameter pack, even when the 37// sequence contains explicitly specified template arguments. 38// FIXME: Actually test what this paragraph specifies. 39#if 0 40void test_explicit_spec_extension() { 41 int *ip1 = first_arg<int *>(0, 0); 42 int *ip2 = first_arg<int *, float*>(0, 0, 0, 0); 43 float *fp1 = first_arg<float *, double*, int*>(0, 0, 0); 44 int i1 = second_arg<float *>(0, 0, 0); 45} 46#endif 47 48