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// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx2b -std=c++2b %s
// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx20 -std=c++20 %s
//cxx2b-no-diagnostics
struct S {
constexpr int operator[](int i) {
return i;
}
constexpr int operator[](int a, int b) { // cxx20-error {{overloaded 'operator[]' cannot have more than one parameter before C++2b}}
return a + b;
}
constexpr int operator[]() { // cxx20-error {{overloaded 'operator[]' cannot have no parameter before C++2b}}
return 42;
}
};
struct Defaults {
constexpr int operator[](int i = 0) { // cxx20-error {{overloaded 'operator[]' cannot have a defaulted parameter before C++2b}}
return 0;
}
constexpr int operator[](int a, int b, int c = 0) { // cxx20-error {{overloaded 'operator[]' cannot have a defaulted parameter before C++2b}}\
// cxx20-error {{cannot have more than one parameter before C++2b}}
return 0;
}
};
template <typename... T>
struct T1 {
constexpr auto operator[](T &&...arg); // cxx20-error {{overloaded 'operator[]' cannot have no parameter before C++2b}} \
// cxx20-error {{overloaded 'operator[]' cannot have more than one parameter before C++2b}}
};
T1<> t10; // cxx20-note {{requested here}}
T1<int, int> t12; // cxx20-note {{requested here}}
T1<int> t11;
struct Variadic {
constexpr int operator[](auto &&...arg) { return 0; }
};
void f() {
S s;
(void)s[0];
(void)s[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\
// cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++2b}}
(void)S{}[]; // cxx20-error {{expected expression}}
(void)Defaults{}[1];
(void)Defaults{}[]; // cxx20-error {{expected expression}}
(void)Defaults{}[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\
// cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++2b}}
Variadic{}[]; // cxx20-error {{expected expression}}
Variadic{}[1];
Variadic{}[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\
// cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++2b}}
}
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