63 lines
2.3 KiB
C++
63 lines
2.3 KiB
C++
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// RUN: %clang_cc1 -std=c++17 -verify=cxx17 -Wc++20-compat %s
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// RUN: %clang_cc1 -std=c++20 -verify=cxx20 -Wc++17-compat %s
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namespace disambig {
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// Cases that are valid in C++17 and before, ill-formed in C++20, and that we
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// should not treat as explicit(bool) as an extension.
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struct A { // cxx20-note +{{}}
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constexpr A() {}
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constexpr operator bool() { return true; }
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constexpr explicit (A)(int); // #1
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// cxx17-warning@#1 {{will be parsed as explicit(bool)}}
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// cxx20-error@#1 +{{}} cxx20-note@#1 +{{}}
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// cxx20-warning@#1 {{incompatible with C++ standards before C++20}}
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// This is ill-formed (via a DR change), and shouldn't be recognized as a
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// constructor (the function declarator cannot be parenthesized in a
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// constructor declaration). But accepting it as an extension seems
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// reasonable.
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// FIXME: Produce an ExtWarn for this.
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constexpr explicit (A(float)); // #1b
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// cxx17-warning@#1b {{will be parsed as explicit(bool)}}
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// cxx20-error@#1b +{{}}
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// cxx20-warning@#1b {{incompatible with C++ standards before C++20}}
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explicit (operator int)(); // #2
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// cxx17-warning@#2 {{will be parsed as explicit(bool)}}
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// cxx20-error@#2 +{{}}
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// cxx20-warning@#2 {{incompatible with C++ standards before C++20}}
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explicit (A::operator float)(); // #2b
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// cxx17-warning@#2b {{will be parsed as explicit(bool)}}
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// cxx17-error@#2b {{extra qualification on member}}
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// cxx20-error@#2b +{{}}
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// cxx20-warning@#2b {{incompatible with C++ standards before C++20}}
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};
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constexpr bool operator+(A) { return true; }
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constexpr bool C = false;
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// Cases that should (ideally) be disambiguated as explicit(bool) in earlier
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// language modes as an extension.
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struct B {
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// Looks like a constructor, but not the constructor of B.
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explicit (A()) B(); // #3
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// cxx17-warning@#3 {{C++20 extension}}
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// cxx20-warning@#3 {{incompatible with C++ standards before C++20}}
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// Looks like a 'constructor' of C. Actually a constructor of B.
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explicit (C)(B)(A); // #4
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// cxx17-warning@#4 {{C++20 extension}}
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// cxx20-warning@#4 {{incompatible with C++ standards before C++20}}
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explicit (operator+(A())) operator int(); // #5
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// cxx17-error@#5 {{requires a type specifier}} cxx17-error@#5 {{expected ';'}}
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// cxx17-warning@#5 {{will be parsed as explicit(bool)}}
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// cxx20-warning@#5 {{incompatible with C++ standards before C++20}}
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};
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}
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