Viewing file:  lambda-sfinae1.C (1.71 KB) -rw-r--r--
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// PR c++/56039
// { dg-do compile { target c++11 } }
template <bool> struct BoolSink { typedef void type; };
template <typename T, typename U>
struct AddRvalueReferenceImpl { typedef T type; };
template <typename T>
struct AddRvalueReferenceImpl<T, typename BoolSink<false &&
[] { // { dg-error "lambda" "" { target c++17_down } }
extern void tref(T&&);
}>::type> {
typedef T &&type;
};
template <typename T>
struct AddRvalueReference : AddRvalueReferenceImpl<T, void> { };
namespace ImplHelpers {
template <typename T>
typename AddRvalueReference<T>::type create(void);
}
template <typename T, typename U, typename ...Args>
struct IsConstructibleImpl { enum { value = 0 }; };
template <typename T, typename ...Args>
struct IsConstructibleImpl<T, typename BoolSink<false &&
[] { T t( ::ImplHelpers::create<Args>() ...); } // { dg-error "" }
>::type, Args ...> {
enum { value = 1 };
};
template <typename T, typename ...Args>
struct IsConstructible : IsConstructibleImpl<T, void, Args ...> { };
struct DestroyMe {
~DestroyMe() = delete;
};
static_assert(+IsConstructible<int>::value, "error");
static_assert(!IsConstructible<void>::value, "error");
static_assert(+IsConstructible<int [1]>::value, "error");
static_assert(!IsConstructible<DestroyMe>::value, "error");
static_assert(!IsConstructible<int *, char *>::value, "error");
static_assert(+IsConstructible<int &&, int>::value, "error");
static_assert(!IsConstructible<int &&, int &>::value, "error");
static_assert(+IsConstructible<int &&, int &&>::value, "error");
// { dg-prune-output "expected" }
// { dg-prune-output "does not name a class" }
// { dg-prune-output "static assertion" }
// { dg-prune-output "template argument . is invalid" }
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