70 lines · cpp
1// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s2// expected-no-diagnostics3 4// Metafunction to extract the Nth type from a set of types.5template<unsigned N, typename ...Types> struct get_nth_type;6 7template<unsigned N, typename Head, typename ...Tail>8struct get_nth_type<N, Head, Tail...> : get_nth_type<N-1, Tail...> { };9 10template<typename Head, typename ...Tail>11struct get_nth_type<0, Head, Tail...> {12 typedef Head type;13};14 15// Placeholder type when get_nth_type fails.16struct no_type {};17 18template<unsigned N>19struct get_nth_type<N> {20 typedef no_type type;21};22 23template<typename ...Args>24typename get_nth_type<0, Args...>::type first_arg(Args...);25 26template<typename ...Args>27typename get_nth_type<1, Args...>::type second_arg(Args...);28 29// Test explicit specification of function template arguments.30void test_explicit_spec_simple() {31 int *ip1 = first_arg<int *>(0);32 int *ip2 = first_arg<int *, float*>(0, 0);33 float *fp1 = first_arg<float *, double*, int*>(0, 0, 0);34}35 36// Template argument deduction can extend the sequence of template37// arguments corresponding to a template parameter pack, even when the38// sequence contains explicitly specified template arguments.39void test_explicit_spec_extension(double *dp) {40 int *ip1 = first_arg<int *>(0, 0);41 int *ip2 = first_arg<int *, float*>(0, 0, 0, 0);42 float *fp1 = first_arg<float *, double*, int*>(0, 0, 0); 43 int *i1 = second_arg<float *>(0, (int*)0, 0); 44 double *dp1 = first_arg<>(dp);45}46 47template<typename ...Types> 48struct tuple { };49 50template<typename ...Types>51void accept_tuple(tuple<Types...>);52 53void test_explicit_spec_extension_targs(tuple<int, float, double> t3) {54 accept_tuple(t3);55 accept_tuple<int, float, double>(t3);56 accept_tuple<int>(t3);57 accept_tuple<int, float>(t3);58}59 60template<typename R, typename ...ParmTypes>61void accept_function_ptr(R(*)(ParmTypes...));62 63void test_explicit_spec_extension_funcparms(int (*f3)(int, float, double)) {64 accept_function_ptr(f3);65 accept_function_ptr<int>(f3);66 accept_function_ptr<int, int>(f3);67 accept_function_ptr<int, int, float>(f3);68 accept_function_ptr<int, int, float, double>(f3);69}70