llvm-project/clang/test/SemaTemplate/constexpr-instantiate.cpp

78 lines
1.9 KiB
C++

// RUN: %clang_cc1 -std=c++11 -verify %s
namespace UseBeforeDefinition {
struct A {
template<typename T> static constexpr T get() { return T(); }
// ok, not a constant expression.
int n = get<int>();
};
// ok, constant expression.
constexpr int j = A::get<int>();
template<typename T> constexpr int consume(T);
// ok, not a constant expression.
const int k = consume(0); // expected-note {{here}}
template<typename T> constexpr int consume(T) { return 0; }
// ok, constant expression.
constexpr int l = consume(0);
constexpr int m = k; // expected-error {{constant expression}} expected-note {{initializer of 'k'}}
}
namespace IntegralConst {
template<typename T> constexpr T f(T n) { return n; }
enum E {
v = f(0), w = f(1) // ok
};
static_assert(w == 1, "");
char arr[f('x')]; // ok
static_assert(sizeof(arr) == 'x', "");
}
namespace ConvertedConst {
template<typename T> constexpr T f(T n) { return n; }
int f() {
switch (f()) {
case f(4): return 0;
}
return 1;
}
}
namespace OverloadResolution {
template<typename T> constexpr T f(T t) { return t; }
template<int n> struct S { };
template<typename T> auto g(T t) -> S<f(sizeof(T))> &;
char &f(...);
template<typename T> auto h(T t[f(sizeof(T))]) -> decltype(&*t) {
return t;
}
S<4> &k = g(0);
int *p, *q = h(p);
}
namespace DataMember {
template<typename T> struct S { static const int k; };
const int n = S<int>::k; // expected-note {{here}}
template<typename T> const int S<T>::k = 0;
constexpr int m = S<int>::k; // ok
constexpr int o = n; // expected-error {{constant expression}} expected-note {{initializer of 'n'}}
}
namespace Reference {
const int k = 5;
template<typename T> struct S {
static volatile int &r;
};
template<typename T> volatile int &S<T>::r = const_cast<volatile int&>(k);
constexpr int n = const_cast<int&>(S<int>::r);
static_assert(n == 5, "");
}