c151225096
Implement P2128R6 in C++23 mode. Unlike GCC's implementation, this doesn't try to recover when a user meant to use a comma expression. Because the syntax changes meaning in C++23, the patch is *NOT* implemented as an extension. Instead, declaring an array with not exactly 1 parameter is an error in older languages modes. There is an off-by-default extension warning in C++23 mode. Unlike the standard, we supports default arguments; Ie, we assume, based on conversations in WG21, that the proposed resolution to CWG2507 will be accepted. We allow arrays OpenMP sections and C++23 multidimensional array to coexist: [a , b] multi dimensional array [a : b] open mp section [a, b: c] // error The rest of the patch is relatively straight forward: we take care to support an arbitrary number of arguments everywhere.
59 lines
2.3 KiB
C++
59 lines
2.3 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx2b -std=c++2b %s
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// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx20 -std=c++20 %s
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//cxx2b-no-diagnostics
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struct S {
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constexpr int operator[](int i) {
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return i;
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}
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constexpr int operator[](int a, int b) { // cxx20-error {{overloaded 'operator[]' cannot have more than one parameter before C++2b}}
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return a + b;
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}
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constexpr int operator[]() { // cxx20-error {{overloaded 'operator[]' cannot have no parameter before C++2b}}
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return 42;
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}
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};
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struct Defaults {
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constexpr int operator[](int i = 0) { // cxx20-error {{overloaded 'operator[]' cannot have a defaulted parameter before C++2b}}
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return 0;
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}
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constexpr int operator[](int a, int b, int c = 0) { // cxx20-error {{overloaded 'operator[]' cannot have a defaulted parameter before C++2b}}\
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// cxx20-error {{cannot have more than one parameter before C++2b}}
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return 0;
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}
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};
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template <typename... T>
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struct T1 {
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constexpr auto operator[](T &&...arg); // cxx20-error {{overloaded 'operator[]' cannot have no parameter before C++2b}} \
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// cxx20-error {{overloaded 'operator[]' cannot have more than one parameter before C++2b}}
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};
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T1<> t10; // cxx20-note {{requested here}}
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T1<int, int> t12; // cxx20-note {{requested here}}
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T1<int> t11;
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struct Variadic {
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constexpr int operator[](auto &&...arg) { return 0; }
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};
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void f() {
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S s;
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(void)s[0];
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(void)s[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\
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// cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++2b}}
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(void)S{}[]; // cxx20-error {{expected expression}}
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(void)Defaults{}[1];
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(void)Defaults{}[]; // cxx20-error {{expected expression}}
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(void)Defaults{}[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\
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// cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++2b}}
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Variadic{}[]; // cxx20-error {{expected expression}}
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Variadic{}[1];
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Variadic{}[1, 2]; // cxx20-warning {{left operand of comma operator has no effect}}\
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// cxx20-warning {{top-level comma expression in array subscript is deprecated in C++20 and unsupported in C++2b}}
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}
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