clang/test/Parser/cxx2b-subscript.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx23 -std=c++23 %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx20 -std=c++20 %s
   3
   4 //cxx23-no-diagnostics
   5
   6 struct 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
  18 struct 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
  28 template <typename... T>
  29 struct 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
  34 T1<> t10;         // cxx20-note {{requested here}}
  35 T1<int, int> t12; // cxx20-note {{requested here}}
  36 T1<int> t11;
  37
  38 struct Variadic {
  39   constexpr int operator[](auto &&...arg) { return 0; }
  40 };
  41
  42 void 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 }