p2.cpp
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// RUN: %clang_cc1 -std=c++2a -verify %s
namespace Rel {
struct A {
int n;
constexpr int operator<=>(A a) const { return n - a.n; }
friend bool operator<(const A&, const A&) = default;
friend bool operator<=(const A&, const A&) = default;
friend bool operator>(const A&, const A&) = default;
friend bool operator>=(const A&, const A&) = default;
};
static_assert(A{0} < A{1});
static_assert(A{1} < A{1}); // expected-error {{failed}}
static_assert(A{0} <= A{1});
static_assert(A{1} <= A{1});
static_assert(A{2} <= A{1}); // expected-error {{failed}}
static_assert(A{1} > A{0});
static_assert(A{1} > A{1}); // expected-error {{failed}}
static_assert(A{1} >= A{0});
static_assert(A{1} >= A{1});
static_assert(A{1} >= A{2}); // expected-error {{failed}}
struct B {
bool operator<=>(B) const = delete; // expected-note 4{{deleted here}} expected-note-re 8{{candidate {{.*}} deleted}}
friend bool operator<(const B&, const B&) = default; // expected-warning {{implicitly deleted}} expected-note {{because it would invoke a deleted comparison}} expected-note-re {{candidate {{.*}} deleted}}
friend bool operator<=(const B&, const B&) = default; // expected-warning {{implicitly deleted}} expected-note {{because it would invoke a deleted comparison}} expected-note-re {{candidate {{.*}} deleted}}
friend bool operator>(const B&, const B&) = default; // expected-warning {{implicitly deleted}} expected-note {{because it would invoke a deleted comparison}} expected-note-re {{candidate {{.*}} deleted}}
friend bool operator>=(const B&, const B&) = default; // expected-warning {{implicitly deleted}} expected-note {{because it would invoke a deleted comparison}} expected-note-re {{candidate {{.*}} deleted}}
};
bool b1 = B() < B(); // expected-error {{deleted}}
bool b2 = B() <= B(); // expected-error {{deleted}}
bool b3 = B() > B(); // expected-error {{deleted}}
bool b4 = B() >= B(); // expected-error {{deleted}}
struct C {
friend bool operator<=>(const C&, const C&);
friend bool operator<(const C&, const C&); // expected-note {{because this non-rewritten comparison function would be the best match}}
bool operator<(const C&) const = default; // expected-warning {{implicitly deleted}}
bool operator>(const C&) const = default; // OK
};
}
// Under P2002R0, operator!= follows these rules too.
namespace NotEqual {
struct A {
int n;
constexpr bool operator==(A a) const { return n == a.n; }
friend bool operator!=(const A&, const A&) = default;
};
static_assert(A{1} != A{2});
static_assert(A{1} != A{1}); // expected-error {{failed}}
struct B {
bool operator==(B) const = delete; // expected-note {{deleted here}} expected-note-re 2{{candidate {{.*}} deleted}}
friend bool operator!=(const B&, const B&) = default; // expected-warning {{implicitly deleted}} expected-note {{because it would invoke a deleted comparison}} expected-note-re {{candidate {{.*}} deleted}}
};
bool b = B() != B(); // expected-error {{deleted}}
struct C {
friend bool operator==(const C&, const C&);
friend bool operator!=(const C&, const C&); // expected-note {{because this non-rewritten comparison function would be the best match}}
bool operator!=(const C&) const = default; // expected-warning {{implicitly deleted}}
};
// Ensure we don't go into an infinite loop diagnosing this: the first function
// is deleted because it calls the second function, which is deleted because it
// calls the first.
struct Evil {
friend bool operator!=(const Evil&, const Evil&) = default; // expected-warning {{implicitly deleted}} expected-note {{would be the best match}}
bool operator!=(const Evil&) const = default; // expected-warning {{implicitly deleted}} expected-note {{would be the best match}}
};
}
namespace Access {
class A {
int operator<=>(A) const; // expected-note {{private}}
};
struct B : A {
friend bool operator<(const B&, const B&) = default; // expected-warning {{implicitly deleted}}
// expected-note@-1 {{defaulted 'operator<' is implicitly deleted because it would invoke a private 'operator<=>' member of 'Access::A'}}
};
}