1 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
3 template<typename ...Types> struct tuple;
4 template<unsigned> struct unsigned_c;
6 template<typename T, typename U>
8 static const bool value = false;
12 struct is_same<T, T> {
13 static const bool value = true;
16 namespace PackExpansionNotAtEnd {
17 template<typename T, typename U>
18 struct tuple_same_with_int {
19 static const bool value = false;
22 template<typename ...Types>
23 struct tuple_same_with_int<tuple<Types...>, tuple<Types..., int>> {
24 static const bool value = true;
27 int tuple_same_with_int_1[tuple_same_with_int<tuple<int, float, double>,
28 tuple<int, float, double, int>
31 template<typename ... Types> struct UselessPartialSpec;
33 template<typename ... Types, // expected-note{{non-deducible template parameter 'Types'}}
34 typename Tail> // expected-note{{non-deducible template parameter 'Tail'}}
35 struct UselessPartialSpec<Types..., Tail>; // expected-error{{class template partial specialization contains template parameters that cannot be deduced; this partial specialization will never be used}}
38 // When a pack expansion occurs within a template argument list, the entire
39 // list is a non-deduced context. For the corresponding case in a function
40 // parameter list, only that parameter is non-deduced.
42 // FIXME: It's not clear that this difference is intended, but the wording is
44 namespace PackExpansionNotAtEndFunctionVersusTemplate {
45 template<typename ...T> struct X {};
46 template<typename ...T, typename U> void f1(void(T..., U));
47 // expected-note@+1 {{couldn't infer template argument 'U'}}
48 template<typename ...T, typename U> void f2(X<T..., U>); // FIXME: ill-formed, U is not deducible
50 void g(int, int, int);
53 // This is deducible: the T... parameter is a non-deduced context, but
54 // that's OK because we don't need to deduce it.
56 // This is not deducible: the T... parameter renders the entire
57 // template-argument-list a non-deduced context, so U is not deducible.
58 f2<int, int>(h); // expected-error {{no matching function}}
61 template<typename T> struct Y;
62 template<typename ...T, // expected-note {{non-deducible template parameter 'T'}}
64 struct Y<void(T..., U)> {}; // expected-error {{cannot be deduced}}
65 template<typename ...T, // expected-note {{non-deducible template parameter 'T'}}
66 typename U> // expected-note {{non-deducible template parameter 'U'}}
67 struct Y<X<T..., U>>; // expected-error {{cannot be deduced}}
68 // FIXME: T is not deducible here, due to [temp.deduct.call]p1:
69 // "When a function parameter pack appears in a non-deduced context,
70 // the type of that pack is never deduced."
71 template<typename ...T,
73 struct Y<void(T..., U, T...)> {};
76 namespace DeduceNonTypeTemplateArgsInArray {
77 template<typename ...ArrayTypes>
80 template<typename ...ElementTypes, unsigned ...Bounds>
81 struct split_arrays<ElementTypes[Bounds]...> {
82 typedef tuple<ElementTypes...> element_types;
84 // FIXME: Would like to have unsigned_tuple<Bounds...> here.
85 typedef tuple<unsigned_c<Bounds>...> bounds_types;
88 int check1[is_same<split_arrays<int[1], float[2], double[3]>::element_types,
89 tuple<int, float, double>>::value? 1 : -1];
90 int check2[is_same<split_arrays<int[1], float[2], double[3]>::bounds_types,
91 tuple<unsigned_c<1>, unsigned_c<2>, unsigned_c<3>>
95 namespace DeduceWithDefaultArgs {
96 template<template<typename...> class Container> void f(Container<int>); // expected-note {{deduced type 'X<[...], (default) int>' of 1st parameter does not match adjusted type 'X<[...], double>' of argument [with Container = X]}}
97 template<typename, typename = int> struct X {};
99 // OK, use default argument for the second template parameter.
104 f(X<int, double>{}); // expected-error {{no matching function for call to 'f'}}