59 lines · cpp
1// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx23 -std=c++23 %s2// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx20 -std=c++20 %s3 4//cxx23-no-diagnostics5 6struct S {7 constexpr int operator[](int i) {8 return i;9 }10 constexpr int operator[](int a, int b) { // cxx20-error {{overloaded 'operator[]' cannot have more than one parameter before C++23}}11 return a + b;12 }13 constexpr int operator[]() { // cxx20-error {{overloaded 'operator[]' cannot have no parameter before C++23}}14 return 42;15 }16};17 18struct Defaults {19 constexpr int operator[](int i = 0) { // cxx20-error {{overloaded 'operator[]' cannot have a defaulted parameter before C++23}}20 return 0;21 }22 constexpr int operator[](int a, int b, int c = 0) { // cxx20-error {{overloaded 'operator[]' cannot have a defaulted parameter before C++23}}\23 // cxx20-error {{cannot have more than one parameter before C++23}}24 return 0;25 }26};27 28template <typename... T>29struct T1 {30 constexpr auto operator[](T &&...arg); // cxx20-error {{overloaded 'operator[]' cannot have no parameter before C++23}} \31 // cxx20-error {{overloaded 'operator[]' cannot have more than one parameter before C++23}}32};33 34T1<> t10; // cxx20-note {{requested here}}35T1<int, int> t12; // cxx20-note {{requested here}}36T1<int> t11;37 38struct Variadic {39 constexpr int operator[](auto &&...arg) { return 0; }40};41 42void f() {43 S s;44 (void)s[0];45 (void)s[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\46 // cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++23}}47 (void)S{}[]; // cxx20-error {{expected expression}}48 49 (void)Defaults{}[1];50 (void)Defaults{}[]; // cxx20-error {{expected expression}}51 (void)Defaults{}[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\52 // cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++23}}53 54 Variadic{}[]; // cxx20-error {{expected expression}}55 Variadic{}[1];56 Variadic{}[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\57 // cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++23}}58}59