p2.cpp revision 5121781d756e7814168b4255a57545d5ca497ec3 
1// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -fcxx-exceptions %s
2
3// An explicitly-defaulted function may be declared constexpr only if it would
4// have been implicitly declared as constexpr.
5struct S1 {
6  constexpr S1() = default; // expected-error {{defaulted definition of default constructor is not constexpr}}
7  constexpr S1(const S1&) = default;
8  constexpr S1(S1&&) = default;
9  constexpr S1 &operator=(const S1&) = default; // expected-error {{explicitly-defaulted copy assignment operator may not have}}
10  constexpr S1 &operator=(S1&&) = default; // expected-error {{explicitly-defaulted move assignment operator may not have}}
11  constexpr ~S1() = default; // expected-error {{destructor cannot be marked constexpr}}
12  int n;
13};
14struct NoCopyMove {
15  constexpr NoCopyMove() {}
16  NoCopyMove(const NoCopyMove&);
17  NoCopyMove(NoCopyMove&&);
18};
19struct S2 {
20  constexpr S2() = default;
21  constexpr S2(const S2&) = default; // expected-error {{defaulted definition of copy constructor is not constexpr}}
22  constexpr S2(S2&&) = default; // expected-error {{defaulted definition of move constructor is not constexpr}}
23  NoCopyMove ncm;
24};
25
26// If a function is explicitly defaulted on its first declaration
27//   -- it is implicitly considered to be constexpr if the implicit declaration
28//      would be
29struct S3 {
30  S3() = default;
31  S3(const S3&) = default;
32  S3(S3&&) = default;
33  constexpr S3(int n) : n(n) {}
34  int n;
35};
36constexpr S3 s3a = S3(0);
37constexpr S3 s3b = s3a;
38constexpr S3 s3c = S3();
39constexpr S3 s3d; // expected-error {{default initialization of an object of const type 'const S3' requires a user-provided default constructor}}
40
41struct S4 {
42  S4() = default;
43  S4(const S4&) = default; // expected-note {{here}}
44  S4(S4&&) = default; // expected-note {{here}}
45  NoCopyMove ncm;
46};
47constexpr S4 s4a{}; // ok
48constexpr S4 s4b = S4(); // expected-error {{constant expression}} expected-note {{non-constexpr constructor}}
49constexpr S4 s4c = s4a; // expected-error {{constant expression}} expected-note {{non-constexpr constructor}}
50
51struct S5 {
52  constexpr S5();
53  int n = 1, m = n + 3;
54};
55constexpr S5::S5() = default;
56static_assert(S5().m == 4, "");
57
58
59// An explicitly-defaulted function may have an exception specification only if
60// it is compatible with the exception specification on an implicit declaration.
61struct E1 {
62  E1() noexcept = default;
63  E1(const E1&) noexcept = default;
64  E1(E1&&) noexcept = default;
65  E1 &operator=(const E1&) noexcept = default;
66  E1 &operator=(E1&&) noexcept = default;
67  ~E1() noexcept = default;
68};
69struct E2 {
70  E2() noexcept(false) = default; // expected-error {{exception specification of explicitly defaulted default constructor does not match the calculated one}}
71  E2(const E2&) noexcept(false) = default; // expected-error {{exception specification of explicitly defaulted copy constructor does not match the calculated one}}
72  E2(E2&&) noexcept(false) = default; // expected-error {{exception specification of explicitly defaulted move constructor does not match the calculated one}}
73  E2 &operator=(const E2&) noexcept(false) = default; // expected-error {{exception specification of explicitly defaulted copy assignment operator does not match the calculated one}}
74  E2 &operator=(E2&&) noexcept(false) = default; // expected-error {{exception specification of explicitly defaulted move assignment operator does not match the calculated one}}
75  ~E2() noexcept(false) = default; // expected-error {{exception specification of explicitly defaulted destructor does not match the calculated one}}
76};
77
78// If a function is explicitly defaulted on its first declaration
79//   -- it is implicitly considered to have the same exception-specification as
80//      if it had been implicitly declared
81struct E3 {
82  E3() = default;
83  E3(const E3&) = default;
84  E3(E3&&) = default;
85  E3 &operator=(const E3&) = default;
86  E3 &operator=(E3&&) = default;
87  ~E3() = default;
88};
89E3 e3;
90static_assert(noexcept(E3(), E3(E3()), E3(e3), e3 = E3(), e3 = e3), "");
91struct E4 {
92  E4() noexcept(false);
93  E4(const E4&) noexcept(false);
94  E4(E4&&) noexcept(false);
95  E4 &operator=(const E4&) noexcept(false);
96  E4 &operator=(E4&&) noexcept(false);
97  ~E4() noexcept(false);
98};
99struct E5 {
100  E5() = default;
101  E5(const E5&) = default;
102  E5(E5&&) = default;
103  E5 &operator=(const E5&) = default;
104  E5 &operator=(E5&&) = default;
105  ~E5() = default;
106
107  E4 e4;
108};
109E5 e5;
110static_assert(!noexcept(E5()), "");
111static_assert(!noexcept(E5(static_cast<E5&&>(e5))), "");
112static_assert(!noexcept(E5(e5)), "");
113static_assert(!noexcept(e5 = E5()), "");
114static_assert(!noexcept(e5 = e5), "");
115
116namespace PR13492 {
117  struct B {
118    B() = default;
119  };
120
121  void f() {
122    const B b; // expected-error {{default initialization of an object of const type 'const PR13492::B' requires a user-provided default constructor}}
123  }
124}
125