Viewing file:  sfinae14.C (2.37 KB) -rw-r--r--
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// DR 339
//
// Test of the use of the new and new[] operators with SFINAE
// Boilerplate helpers
typedef char yes_type;
struct no_type { char data[2]; };
template<typename T> T create_a();
template<typename T> struct type { };
template<bool, typename T = void> struct enable_if { typedef T type; };
template<typename T> struct enable_if<false, T> { };
#define JOIN( X, Y ) DO_JOIN( X, Y )
#define DO_JOIN( X, Y ) DO_JOIN2(X,Y)
#define DO_JOIN2( X, Y ) X##Y
template<typename T>
typename enable_if<(sizeof(new T, 0) > 0), yes_type>::type
check_new(int);
template<typename T> no_type check_new(...);
template<typename T>
struct has_new
{
static const bool value =
(sizeof(check_new<T>(0)) == sizeof(yes_type));
};
template<typename T, typename U>
typename enable_if<(sizeof((new T(create_a<U>())), 0) > 0),
yes_type>::type
check_new_one_arg(int);
template<typename T, typename U> no_type check_new_one_arg(...);
template<typename T, typename U>
struct has_new_one_arg
{
static const bool value =
(sizeof(check_new_one_arg<T, U>(0)) == sizeof(yes_type));
};
template<typename T, typename U, U N>
typename enable_if<(sizeof(new T[N], 0) > 0), yes_type>::type
check_array_new(int);
template<typename T, typename U, U N> no_type check_array_new(...);
template<typename T, typename U, U N>
struct has_array_new
{
static const bool value =
(sizeof(check_array_new<T, U, N>(0)) == sizeof(yes_type));
};
#ifdef __GXX_EXPERIMENTAL_CXX0X__
# define STATIC_ASSERT(Expr) static_assert(Expr, #Expr)
#else
# define STATIC_ASSERT(Expr) int JOIN(a,__LINE__)[Expr? 1 : -1]
#endif
struct X {
X(int);
};
struct Y { int foo; };
STATIC_ASSERT((has_new<Y>::value));
STATIC_ASSERT(!(has_new<X>::value));
STATIC_ASSERT((has_new_one_arg<Y, Y>::value));
STATIC_ASSERT((has_new_one_arg<X, float>::value));
STATIC_ASSERT(!(has_new_one_arg<X, int X::*>::value));
STATIC_ASSERT((has_array_new<Y, int, 5>::value));
STATIC_ASSERT(!(has_array_new<X, int Y::*, &Y::foo>::value));
STATIC_ASSERT(!(has_array_new<X, int, 5>::value));
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