1 // RUN: %clang_cc1 -std=c++2a -verify %s
2
3 struct A {};
4 struct B { bool operator==(B) const; };
5 struct C { int operator==(C) const; };
6 struct D {
7 // expected-note@+2 {{candidate function not viable: 'this' argument has type 'const}}
8 // expected-note@+1 {{candidate function (with reversed parameter order) not viable: 1st argument ('const}}
9 bool operator==(D);
10 };
11 struct E {
12 E(const E &) = delete; // expected-note {{deleted}}
13 int operator==(E) const; // expected-note {{passing}}
14 };
15 struct F { void operator==(F) const; };
16 struct G { bool operator==(G) const = delete; }; // expected-note {{deleted here}}
17
18 template<typename T> struct X {
19 X();
20 bool operator==(const X&) const = default; // #x expected-note 4{{deleted here}}
21 T t; // expected-note 3{{because there is no viable comparison function for member 't'}}
22 // expected-note@-1 {{because it would invoke a deleted comparison function for member 't'}}
23 };
24
25 struct Mutable {
26 bool operator==(const Mutable&) const = default;
27 mutable D d;
28 };
29
test()30 void test() {
31 void(X<A>() == X<A>()); // expected-error {{cannot be compared because its 'operator==' is implicitly deleted}}
32 void(X<B>() == X<B>());
33 void(X<C>() == X<C>());
34 void(X<D>() == X<D>()); // expected-error {{cannot be compared because its 'operator==' is implicitly deleted}}
35 void(Mutable() == Mutable());
36
37 // FIXME: We would benefit from a note identifying the member of 'X' we were comparing here and below.
38 // expected-error@#x {{call to deleted constructor of 'E'}}
39 void(X<E>() == X<E>()); // expected-note {{in defaulted equality comparison operator for 'X<E>' first required here}}
40
41 // FIXME: We would benefit from a note pointing at the selected 'operator==' here.
42 // expected-error@#x {{value of type 'void' is not contextually convertible to 'bool'}}
43 void(X<F>() == X<F>()); // expected-note {{in defaulted equality comparison operator for 'X<F>' first required here}}
44
45 void(X<G>() == X<G>()); // expected-error {{cannot be compared because its 'operator==' is implicitly deleted}}
46
47 void(X<A[3]>() == X<A[3]>()); // expected-error {{cannot be compared because its 'operator==' is implicitly deleted}}
48 void(X<B[3]>() == X<B[3]>());
49 }
50
51 namespace Access {
52 class A {
53 bool operator==(const A &) const; // expected-note 2{{implicitly declared private here}}
54 };
55 struct B : A { // expected-note 2{{because it would invoke a private 'operator==' to compare base class 'A'}}
56 bool operator==(const B &) const = default; // expected-warning {{deleted}}
57 friend bool operator==(const B &, const B &) = default; // expected-warning {{deleted}}
58 };
59
60 class C {
61 protected:
62 bool operator==(const C &) const; // expected-note 2{{declared protected here}}
63 };
64 struct D : C {
65 bool operator==(const D &) const = default;
66 friend bool operator==(const D &, const D&) = default;
67 };
68 struct E {
69 C c; // expected-note 2{{because it would invoke a protected 'operator==' member of 'Access::C' to compare member 'c'}}
70 bool operator==(const E &) const = default; // expected-warning {{deleted}}
71 friend bool operator==(const E &, const E &) = default; // expected-warning {{deleted}}
72 };
73
74 struct F : C {
75 using C::operator==;
76 };
77 struct G : F {
78 bool operator==(const G&) const = default;
79 friend bool operator==(const G&, const G&) = default;
80 };
81
82 struct H : C {
83 private:
84 using C::operator==; // expected-note 2{{declared private here}}
85 };
86 struct I : H { // expected-note 2{{private 'operator==' to compare base class 'H'}}
87 bool operator==(const I&) const = default; // expected-warning {{deleted}}
88 friend bool operator==(const I&, const I&) = default; // expected-warning {{deleted}}
89 };
90
91 class J {
92 bool operator==(const J&) const;
93 friend class K;
94 };
95 class K {
96 J j;
97 bool operator==(const K&) const = default;
98 friend bool operator==(const K&, const K&) = default;
99 };
100
101 struct X {
102 bool operator==(const X&) const; // expected-note {{ambiguity is between a regular call to this operator and a call with the argument order reversed}}
103 };
104 struct Y : private X { // expected-note {{private}}
105 using X::operator==;
106 };
107 struct Z : Y {
108 // Note: this function is not deleted. The selected operator== is
109 // accessible. But the derived-to-base conversion involves an inaccessible
110 // base class, which we don't check for until we define the function.
111 bool operator==(const Z&) const = default; // expected-error {{cannot cast 'const Access::Y' to its private base class 'const Access::X'}} expected-warning {{ambiguous}}
112 };
113 bool z = Z() == Z(); // expected-note {{first required here}}
114 }
115