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// RUN: %clang_cc1 -std=c++2a -verify %s
namespace std {
class strong_ordering {
int n;
constexpr strong_ordering(int n) : n(n) {}
public:
static const strong_ordering less, equal, greater;
bool operator!=(int) { return n != 0; }
};
constexpr strong_ordering strong_ordering::less{-1},
strong_ordering::equal{0}, strong_ordering::greater{1};
class weak_ordering {
int n;
constexpr weak_ordering(int n) : n(n) {}
public:
constexpr weak_ordering(strong_ordering o);
static const weak_ordering less, equivalent, greater;
bool operator!=(int) { return n != 0; }
};
constexpr weak_ordering weak_ordering::less{-1},
weak_ordering::equivalent{0}, weak_ordering::greater{1};
class partial_ordering {
int n;
constexpr partial_ordering(int n) : n(n) {}
public:
constexpr partial_ordering(strong_ordering o);
constexpr partial_ordering(weak_ordering o);
static const partial_ordering less, equivalent, greater, unordered;
bool operator!=(int) { return n != 0; }
};
constexpr partial_ordering partial_ordering::less{-1},
partial_ordering::equivalent{0}, partial_ordering::greater{1},
partial_ordering::unordered{2};
}
namespace DeducedNotCat {
struct A {
A operator<=>(const A&) const; // expected-note {{selected 'operator<=>' for member 'a' declared here}}
};
struct B {
A a; // expected-note {{return type 'DeducedNotCat::A' of three-way comparison for member 'a' is not a standard comparison category type}}
auto operator<=>(const B&) const = default; // expected-warning {{implicitly deleted}}
};
}
namespace DeducedVsSynthesized {
struct A {
bool operator==(const A&) const;
bool operator<(const A&) const;
};
struct B {
A a; // expected-note {{no viable comparison function for member 'a'}}
auto operator<=>(const B&) const = default; // expected-warning {{implicitly deleted}}
};
}
namespace Deduction {
template<typename T> struct wrap {
T t;
friend auto operator<=>(const wrap&, const wrap&) = default;
};
using strong = wrap<int>;
using strong2 = wrap<int*>;
struct weak {
friend std::weak_ordering operator<=>(weak, weak);
};
using partial = wrap<float>;
template<typename ...T> struct A : T... {
friend auto operator<=>(const A&, const A&) = default;
};
template<typename Expected, typename ...Ts> void f() {
using T = Expected; // expected-note {{previous}}
using T = decltype(A<Ts...>() <=> A<Ts...>()); // expected-error {{different type}}
void(A<Ts...>() <=> A<Ts...>()); // trigger synthesis of body
}
template void f<std::strong_ordering>();
template void f<std::strong_ordering, strong>();
template void f<std::strong_ordering, strong, strong2>();
template void f<std::weak_ordering, weak>();
template void f<std::weak_ordering, weak, strong>();
template void f<std::weak_ordering, strong, weak>();
template void f<std::partial_ordering, partial>();
template void f<std::partial_ordering, weak, partial>();
template void f<std::partial_ordering, strong, partial>();
template void f<std::partial_ordering, partial, weak>();
template void f<std::partial_ordering, partial, strong>();
template void f<std::partial_ordering, weak, partial, strong>();
// Check that the above mechanism works.
template void f<std::strong_ordering, weak>(); // expected-note {{instantiation of}}
}
namespace BadDeducedType {
struct A {
// expected-error@+1 {{deduced return type for defaulted three-way comparison operator must be 'auto', not 'auto &'}}
friend auto &operator<=>(const A&, const A&) = default;
};
struct B {
// expected-error@+1 {{deduced return type for defaulted three-way comparison operator must be 'auto', not 'const auto'}}
friend const auto operator<=>(const B&, const B&) = default;
};
template<typename T> struct X {}; // expected-note {{here}}
struct C {
// expected-error@+1 {{deduction not allowed in function return type}}
friend X operator<=>(const C&, const C&) = default;
};
template<typename T> concept CmpCat = true;
struct D {
// expected-error@+1 {{deduced return type for defaulted three-way comparison operator must be 'auto', not 'CmpCat auto'}}
friend CmpCat auto operator<=>(const D&, const D&) = default;
};
}
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