1 // RUN: %clang_cc1 -std=c++11 -verify %s 2 3 namespace UseBeforeDefinition { 4 struct A { 5 template<typename T> static constexpr T get() { return T(); } 6 // ok, not a constant expression. 7 int n = get<int>(); 8 }; 9 10 // ok, constant expression. 11 constexpr int j = A::get<int>(); 12 13 template<typename T> constexpr int consume(T); 14 // ok, not a constant expression. 15 const int k = consume(0); // expected-note {{here}} 16 17 template<typename T> constexpr int consume(T) { return 0; } 18 // ok, constant expression. 19 constexpr int l = consume(0); 20 21 constexpr int m = k; // expected-error {{constant expression}} expected-note {{initializer of 'k'}} 22 } 23 24 namespace IntegralConst { 25 template<typename T> constexpr T f(T n) { return n; } 26 enum E { 27 v = f(0), w = f(1) // ok 28 }; 29 static_assert(w == 1, ""); 30 31 char arr[f('x')]; // ok 32 static_assert(sizeof(arr) == 'x', ""); 33 } 34 35 namespace ConvertedConst { 36 template<typename T> constexpr T f(T n) { return n; } 37 int f() { 38 switch (f()) { 39 case f(4): return 0; 40 } 41 return 1; 42 } 43 } 44 45 namespace OverloadResolution { 46 template<typename T> constexpr T f(T t) { return t; } 47 48 template<int n> struct S { }; 49 50 template<typename T> auto g(T t) -> S<f(sizeof(T))> &; 51 char &f(...); 52 53 template<typename T> auto h(T t[f(sizeof(T))]) -> decltype(&*t) { 54 return t; 55 } 56 57 S<4> &k = g(0); 58 int *p, *q = h(p); 59 } 60 61 namespace DataMember { 62 template<typename T> struct S { static const int k; }; 63 const int n = S<int>::k; // expected-note {{here}} 64 template<typename T> const int S<T>::k = 0; 65 constexpr int m = S<int>::k; // ok 66 constexpr int o = n; // expected-error {{constant expression}} expected-note {{initializer of 'n'}} 67 } 68 69 namespace Reference { 70 const int k = 5; 71 template<typename T> struct S { 72 static volatile int &r; 73 }; 74 template<typename T> volatile int &S<T>::r = const_cast<volatile int&>(k); 75 constexpr int n = const_cast<int&>(S<int>::r); 76 static_assert(n == 5, ""); 77 } 78
