1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
2
3 struct notlit { // expected-note {{not literal because}}
notlitnotlit4 notlit() {}
5 };
6 struct notlit2 {
notlit2notlit27 notlit2() {}
8 };
9
10 // valid declarations
11 constexpr int i1 = 0;
f1()12 constexpr int f1() { return 0; }
13 struct s1 {
14 constexpr static int mi1 = 0;
15 const static int mi2;
16 };
17 constexpr int s1::mi2 = 0;
18
19 // invalid declarations
20 // not a definition of an object
21 constexpr extern int i2; // expected-error {{constexpr variable declaration must be a definition}}
22 // not a literal type
23 constexpr notlit nl1; // expected-error {{constexpr variable cannot have non-literal type 'const notlit'}}
24 // function parameters
f2(constexpr int i)25 void f2(constexpr int i) {} // expected-error {{function parameter cannot be constexpr}}
26 // non-static member
27 struct s2 {
28 constexpr int mi1; // expected-error {{non-static data member cannot be constexpr; did you intend to make it const?}}
29 static constexpr int mi2; // expected-error {{requires an initializer}}
30 mutable constexpr int mi3 = 3; // expected-error-re {{non-static data member cannot be constexpr$}} expected-error {{'mutable' and 'const' cannot be mixed}}
31 };
32 // typedef
33 typedef constexpr int CI; // expected-error {{typedef cannot be constexpr}}
34 // tag
35 constexpr class C1 {}; // expected-error {{class cannot be marked constexpr}}
36 constexpr struct S1 {}; // expected-error {{struct cannot be marked constexpr}}
37 constexpr union U1 {}; // expected-error {{union cannot be marked constexpr}}
38 constexpr enum E1 {}; // expected-error {{enum cannot be marked constexpr}}
39 template <typename T> constexpr class TC1 {}; // expected-error {{class cannot be marked constexpr}}
40 template <typename T> constexpr struct TS1 {}; // expected-error {{struct cannot be marked constexpr}}
41 template <typename T> constexpr union TU1 {}; // expected-error {{union cannot be marked constexpr}}
42 class C2 {} constexpr; // expected-error {{class cannot be marked constexpr}}
43 struct S2 {} constexpr; // expected-error {{struct cannot be marked constexpr}}
44 union U2 {} constexpr; // expected-error {{union cannot be marked constexpr}}
45 enum E2 {} constexpr; // expected-error {{enum cannot be marked constexpr}}
46 constexpr class C3 {} c3 = C3();
47 constexpr struct S3 {} s3 = S3();
48 constexpr union U3 {} u3 = {};
49 constexpr enum E3 { V3 } e3 = V3;
50 class C4 {} constexpr c4 = C4();
51 struct S4 {} constexpr s4 = S4();
52 union U4 {} constexpr u4 = {};
53 enum E4 { V4 } constexpr e4 = V4;
54 constexpr int; // expected-error {{constexpr can only be used in variable and function declarations}}
55 // redeclaration mismatch
56 constexpr int f3(); // expected-note {{previous declaration is here}}
57 int f3(); // expected-error {{non-constexpr declaration of 'f3' follows constexpr declaration}}
58 int f4(); // expected-note {{previous declaration is here}}
59 constexpr int f4(); // expected-error {{constexpr declaration of 'f4' follows non-constexpr declaration}}
60 template<typename T> constexpr T f5(T);
61 template<typename T> constexpr T f5(T); // expected-note {{previous}}
62 template<typename T> T f5(T); // expected-error {{non-constexpr declaration of 'f5' follows constexpr declaration}}
63 template<typename T> T f6(T); // expected-note {{here}}
64 template<typename T> constexpr T f6(T); // expected-error {{constexpr declaration of 'f6' follows non-constexpr declaration}}
65 // destructor
66 struct ConstexprDtor {
67 constexpr ~ConstexprDtor() = default; // expected-error {{destructor cannot be marked constexpr}}
68 };
69
70 // template stuff
ft(T t)71 template <typename T> constexpr T ft(T t) { return t; }
gt(T t)72 template <typename T> T gt(T t) { return t; }
73 struct S {
74 template<typename T> constexpr T f();
75 template<typename T> T g() const;
76 };
77
78 // explicit specialization can differ in constepxr
ft(notlit nl)79 template <> notlit ft(notlit nl) { return nl; }
ft(char c)80 template <> char ft(char c) { return c; } // expected-note {{previous}}
81 template <> constexpr char ft(char nl); // expected-error {{constexpr declaration of 'ft<char>' follows non-constexpr declaration}}
gt(int nl)82 template <> constexpr int gt(int nl) { return nl; }
f() const83 template <> notlit S::f() const { return notlit(); }
g()84 template <> constexpr int S::g() { return 0; } // expected-note {{previous}}
85 template <> int S::g() const; // expected-error {{non-constexpr declaration of 'g<int>' follows constexpr declaration}}
86 // specializations can drop the 'constexpr' but not the implied 'const'.
g()87 template <> char S::g() { return 0; } // expected-error {{no function template matches}}
g() const88 template <> double S::g() const { return 0; } // ok
89
90 constexpr int i3 = ft(1);
91
test()92 void test() {
93 // ignore constexpr when instantiating with non-literal
94 notlit2 nl2;
95 (void)ft(nl2);
96 }
97
98 // Examples from the standard:
99 constexpr int square(int x); // expected-note {{declared here}}
100 constexpr int bufsz = 1024;
101
102 constexpr struct pixel { // expected-error {{struct cannot be marked constexpr}}
103 int x;
104 int y;
105 constexpr pixel(int);
106 };
107
pixel(int a)108 constexpr pixel::pixel(int a)
109 : x(square(a)), y(square(a)) // expected-note {{undefined function 'square' cannot be used in a constant expression}}
110 { }
111
112 constexpr pixel small(2); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'pixel(2)'}}
113
square(int x)114 constexpr int square(int x) {
115 return x * x;
116 }
117
118 constexpr pixel large(4);
119
next(constexpr int x)120 int next(constexpr int x) { // expected-error {{function parameter cannot be constexpr}}
121 return x + 1;
122 }
123
124 extern constexpr int memsz; // expected-error {{constexpr variable declaration must be a definition}}
125