1 // RUN: %clang_cc1 -std=c++11 -verify %s
2
3 template<int> struct X {};
4
5 // Constructor characteristics are:
6 // - the template parameter list
7 // - the parameter-type-list
8 // - absence or presence of explicit
9 // - absence or presence of constexpr
10 struct A {
AA11 A(X<0>) {} // expected-note 2{{here}}
AA12 constexpr A(X<1>) {}
AA13 explicit A(X<2>) {} // expected-note 3{{here}}
AA14 explicit constexpr A(X<3>) {} // expected-note 2{{here}}
15 };
16
17 A a0 { X<0>{} };
18 A a0i = { X<0>{} };
19 constexpr A a0c { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
20 constexpr A a0ic = { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
21
22 A a1 { X<1>{} };
23 A a1i = { X<1>{} };
24 constexpr A a1c { X<1>{} };
25 constexpr A a1ic = { X<1>{} };
26
27 A a2 { X<2>{} };
28 A a2i = { X<2>{} }; // expected-error {{constructor is explicit}}
29 constexpr A a2c { X<2>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
30 constexpr A a2ic = { X<2>{} }; // expected-error {{constructor is explicit}}
31
32 A a3 { X<3>{} };
33 A a3i = { X<3>{} }; // expected-error {{constructor is explicit}}
34 constexpr A a3c { X<3>{} };
35 constexpr A a3ic = { X<3>{} }; // expected-error {{constructor is explicit}}
36
37
38 struct B : A {
39 using A::A; // expected-note 7{{here}}
40 };
41
42 B b0 { X<0>{} };
43 B b0i = { X<0>{} };
44 constexpr B b0c { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
45 constexpr B b0ic = { X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
46
47 B b1 { X<1>{} };
48 B b1i = { X<1>{} };
49 constexpr B b1c { X<1>{} };
50 constexpr B b1ic = { X<1>{} };
51
52 B b2 { X<2>{} };
53 B b2i = { X<2>{} }; // expected-error {{constructor is explicit}}
54 constexpr B b2c { X<2>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
55 constexpr B b2ic = { X<2>{} }; // expected-error {{constructor is explicit}}
56
57 B b3 { X<3>{} };
58 B b3i = { X<3>{} }; // expected-error {{constructor is explicit}}
59 constexpr B b3c { X<3>{} };
60 constexpr B b3ic = { X<3>{} }; // expected-error {{constructor is explicit}}
61
62
63 // 'constexpr' is OK even if the constructor doesn't obey the constraints.
64 struct NonLiteral { NonLiteral(); };
65 struct NonConstexpr { NonConstexpr(); constexpr NonConstexpr(int); }; // expected-note {{here}}
ConstexprConstexpr66 struct Constexpr { constexpr Constexpr(int) {} };
67
68 struct BothNonLiteral : NonLiteral, Constexpr { using Constexpr::Constexpr; }; // expected-note {{base class 'NonLiteral' of non-literal type}}
69 constexpr BothNonLiteral bothNL{42}; // expected-error {{constexpr variable cannot have non-literal type 'const BothNonLiteral'}}
70
71 struct BothNonConstexpr : NonConstexpr, Constexpr { using Constexpr::Constexpr; }; // expected-note {{non-constexpr constructor 'NonConstexpr}}
72 constexpr BothNonConstexpr bothNC{42}; // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'BothNonConstexpr(42)'}}
73
74
75 struct ConstexprEval {
ConstexprEvalConstexprEval76 constexpr ConstexprEval(int a, const char *p) : k(p[a]) {}
77 char k;
78 };
79 struct ConstexprEval2 {
80 char k2 = 'x';
81 };
82 struct ConstexprEval3 : ConstexprEval, ConstexprEval2 {
83 using ConstexprEval::ConstexprEval;
84 };
85 constexpr ConstexprEval3 ce{4, "foobar"};
86 static_assert(ce.k == 'a', "");
87 static_assert(ce.k2 == 'x', "");
88
89
90 struct TemplateCtors {
TemplateCtorsTemplateCtors91 constexpr TemplateCtors() {}
92 template<template<int> class T> TemplateCtors(X<0>, T<0>);
93 template<int N> TemplateCtors(X<1>, X<N>);
94 template<typename T> TemplateCtors(X<2>, T);
95
96 template<typename T = int> TemplateCtors(int, int = 0, int = 0); // expected-note {{inherited from here}}
97 };
98
99 struct UsingTemplateCtors : TemplateCtors { // expected-note 2{{candidate is the implicit}}
100 using TemplateCtors::TemplateCtors; // expected-note 4{{here}} expected-note {{candidate}}
101
UsingTemplateCtorsUsingTemplateCtors102 constexpr UsingTemplateCtors(X<0>, X<0>) {}
UsingTemplateCtorsUsingTemplateCtors103 constexpr UsingTemplateCtors(X<1>, X<1>) {}
UsingTemplateCtorsUsingTemplateCtors104 constexpr UsingTemplateCtors(X<2>, X<2>) {}
105
UsingTemplateCtorsUsingTemplateCtors106 template<int = 0> constexpr UsingTemplateCtors(int) {} // expected-note {{candidate}}
UsingTemplateCtorsUsingTemplateCtors107 template<typename T = void> constexpr UsingTemplateCtors(int, int) {}
UsingTemplateCtorsUsingTemplateCtors108 template<typename T, typename U> constexpr UsingTemplateCtors(int, int, int) {}
109 };
110
111 template<int> struct Y {};
112 constexpr UsingTemplateCtors uct1{ X<0>{}, X<0>{} };
113 constexpr UsingTemplateCtors uct2{ X<0>{}, Y<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
114 constexpr UsingTemplateCtors uct3{ X<1>{}, X<0>{} }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
115 constexpr UsingTemplateCtors uct4{ X<1>{}, X<1>{} };
116 constexpr UsingTemplateCtors uct5{ X<2>{}, 0 }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
117 constexpr UsingTemplateCtors uct6{ X<2>{}, X<2>{} };
118
119 constexpr UsingTemplateCtors utc7{ 0 }; // expected-error {{ambiguous}}
120 constexpr UsingTemplateCtors utc8{ 0, 0 }; // ok
121 constexpr UsingTemplateCtors utc9{ 0, 0, 0 }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr}}
122