1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s 2 3 struct notlit { // expected-note {{not literal because}} 4 notlit() {} 5 }; 6 struct notlit2 { 7 notlit2() {} 8 }; 9 10 // valid declarations 11 constexpr int i1 = 0; 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 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}} 29 static constexpr int mi2; // expected-error {{requires an initializer}} 30 }; 31 // typedef 32 typedef constexpr int CI; // expected-error {{typedef cannot be constexpr}} 33 // tag 34 constexpr class C1 {}; // expected-error {{class cannot be marked constexpr}} 35 constexpr struct S1 {}; // expected-error {{struct cannot be marked constexpr}} 36 constexpr union U1 {}; // expected-error {{union cannot be marked constexpr}} 37 constexpr enum E1 {}; // expected-error {{enum cannot be marked constexpr}} 38 template <typename T> constexpr class TC1 {}; // expected-error {{class cannot be marked constexpr}} 39 template <typename T> constexpr struct TS1 {}; // expected-error {{struct cannot be marked constexpr}} 40 template <typename T> constexpr union TU1 {}; // expected-error {{union cannot be marked constexpr}} 41 class C2 {} constexpr; // expected-error {{class cannot be marked constexpr}} 42 struct S2 {} constexpr; // expected-error {{struct cannot be marked constexpr}} 43 union U2 {} constexpr; // expected-error {{union cannot be marked constexpr}} 44 enum E2 {} constexpr; // expected-error {{enum cannot be marked constexpr}} 45 constexpr class C3 {} c3 = C3(); 46 constexpr struct S3 {} s3 = S3(); 47 constexpr union U3 {} u3 = {}; 48 constexpr enum E3 { V3 } e3 = V3; 49 class C4 {} constexpr c4 = C4(); 50 struct S4 {} constexpr s4 = S4(); 51 union U4 {} constexpr u4 = {}; 52 enum E4 { V4 } constexpr e4 = V4; 53 constexpr int; // expected-error {{constexpr can only be used in variable and function declarations}} 54 // redeclaration mismatch 55 constexpr int f3(); // expected-note {{previous declaration is here}} 56 int f3(); // expected-error {{non-constexpr declaration of 'f3' follows constexpr declaration}} 57 int f4(); // expected-note {{previous declaration is here}} 58 constexpr int f4(); // expected-error {{constexpr declaration of 'f4' follows non-constexpr declaration}} 59 template<typename T> constexpr T f5(T); 60 template<typename T> constexpr T f5(T); // expected-note {{previous}} 61 template<typename T> T f5(T); // expected-error {{non-constexpr declaration of 'f5' follows constexpr declaration}} 62 template<typename T> T f6(T); // expected-note {{here}} 63 template<typename T> constexpr T f6(T); // expected-error {{constexpr declaration of 'f6' follows non-constexpr declaration}} 64 // destructor 65 struct ConstexprDtor { 66 constexpr ~ConstexprDtor() = default; // expected-error {{destructor cannot be marked constexpr}} 67 }; 68 69 // template stuff 70 template <typename T> constexpr T ft(T t) { return t; } 71 template <typename T> T gt(T t) { return t; } 72 struct S { 73 template<typename T> constexpr T f(); 74 template<typename T> T g() const; 75 }; 76 77 // explicit specialization can differ in constepxr 78 template <> notlit ft(notlit nl) { return nl; } 79 template <> char ft(char c) { return c; } // expected-note {{previous}} 80 template <> constexpr char ft(char nl); // expected-error {{constexpr declaration of 'ft<char>' follows non-constexpr declaration}} 81 template <> constexpr int gt(int nl) { return nl; } 82 template <> notlit S::f() const { return notlit(); } 83 template <> constexpr int S::g() { return 0; } // expected-note {{previous}} 84 template <> int S::g() const; // expected-error {{non-constexpr declaration of 'g<int>' follows constexpr declaration}} 85 // specializations can drop the 'constexpr' but not the implied 'const'. 86 template <> char S::g() { return 0; } // expected-error {{no function template matches}} 87 template <> double S::g() const { return 0; } // ok 88 89 constexpr int i3 = ft(1); 90 91 void test() { 92 // ignore constexpr when instantiating with non-literal 93 notlit2 nl2; 94 (void)ft(nl2); 95 } 96 97 // Examples from the standard: 98 constexpr int square(int x); // expected-note {{declared here}} 99 constexpr int bufsz = 1024; 100 101 constexpr struct pixel { // expected-error {{struct cannot be marked constexpr}} 102 int x; 103 int y; 104 constexpr pixel(int); 105 }; 106 107 constexpr pixel::pixel(int a) 108 : x(square(a)), y(square(a)) // expected-note {{undefined function 'square' cannot be used in a constant expression}} 109 { } 110 111 constexpr pixel small(2); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'pixel(2)'}} 112 113 constexpr int square(int x) { 114 return x * x; 115 } 116 117 constexpr pixel large(4); 118 119 int next(constexpr int x) { // expected-error {{function parameter cannot be constexpr}} 120 return x + 1; 121 } 122 123 extern constexpr int memsz; // expected-error {{constexpr variable declaration must be a definition}} 124
