| // RUN: %clang_cc1 -verify -std=c++2b %s |
| |
| namespace N { |
| |
| void empty() { |
| struct S { |
| int operator[](); // expected-note{{not viable: requires 0 arguments, but 1 was provided}} |
| }; |
| |
| S{}[]; |
| S{}[1]; // expected-error {{no viable overloaded operator[] for type 'S'}} |
| } |
| |
| void default_var() { |
| struct S { |
| constexpr int operator[](int i = 42) { return i; } // expected-note {{not viable: allows at most single argument 'i'}} |
| }; |
| static_assert(S{}[] == 42); |
| static_assert(S{}[1] == 1); |
| static_assert(S{}[1, 2] == 1); // expected-error {{no viable overloaded operator[] for type 'S'}} |
| } |
| |
| struct Variadic { |
| constexpr int operator[](auto... i) { return (42 + ... + i); } |
| }; |
| |
| void variadic() { |
| |
| static_assert(Variadic{}[] == 42); |
| static_assert(Variadic{}[1] == 43); |
| static_assert(Variadic{}[1, 2] == 45); |
| } |
| |
| void multiple() { |
| struct S { |
| constexpr int operator[]() { return 0; } |
| constexpr int operator[](int) { return 1; }; |
| constexpr int operator[](int, int) { return 2; }; |
| }; |
| static_assert(S{}[] == 0); |
| static_assert(S{}[1] == 1); |
| static_assert(S{}[1, 1] == 2); |
| } |
| |
| void ambiguous() { |
| struct S { |
| constexpr int operator[]() { return 0; } // expected-note{{candidate function}} |
| constexpr int operator[](int = 0) { return 1; }; // expected-note{{candidate function}} |
| }; |
| |
| static_assert(S{}[] == 0); // expected-error{{call to subscript operator of type 'S' is ambiguous}} |
| } |
| } // namespace N |
| |
| template <typename... T> |
| struct T1 { |
| constexpr auto operator[](T... arg) { // expected-note {{candidate function not viable: requires 2 arguments, but 1 was provided}} |
| return (1 + ... + arg); |
| } |
| }; |
| |
| static_assert(T1<>{}[] == 1); |
| static_assert(T1<int>{}[1] == 2); |
| static_assert(T1<int, int>{}[1, 1] == 3); |
| static_assert(T1<int, int>{}[1] == 3); // expected-error {{no viable overloaded operator[] for type 'T1<int, int>'}} |
| |
| struct T2 { |
| constexpr auto operator[](auto... arg) { |
| return (1 + ... + arg); |
| } |
| }; |
| |
| static_assert(T2{}[] == 1); |
| static_assert(T2{}[1] == 2); |
| static_assert(T2{}[1, 1] == 3); |