https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107600
Bug ID: 107600
Summary: New __is_destructible built-in
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
Like __is_construcible, __is_convertible, __is_assignable, it would be nice to
have an __is_destructible built-in so we don't need to instantiate all this for
every one of the C++20 concepts that depends on it:
// In N3290 is_destructible does not say anything about function
// types and abstract types, see LWG 2049. This implementation
// describes function types as non-destructible and all complete
// object types as destructible, iff the explicit destructor
// call expression is wellformed.
struct __do_is_destructible_impl
{
template<typename _Tp, typename = decltype(declval<_Tp&>().~_Tp())>
static true_type __test(int);
template<typename>
static false_type __test(...);
};
template<typename _Tp>
struct __is_destructible_impl
: public __do_is_destructible_impl
{
typedef decltype(__test<_Tp>(0)) type;
};
template<typename _Tp,
bool = __or_<is_void<_Tp>,
__is_array_unknown_bounds<_Tp>,
is_function<_Tp>>::value,
bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
struct __is_destructible_safe;
template<typename _Tp>
struct __is_destructible_safe<_Tp, false, false>
: public __is_destructible_impl<typename
remove_all_extents<_Tp>::type>::type
{ };
template<typename _Tp>
struct __is_destructible_safe<_Tp, true, false>
: public false_type { };
template<typename _Tp>
struct __is_destructible_safe<_Tp, false, true>
: public true_type { };
/// @endcond
/// is_destructible
template<typename _Tp>
struct is_destructible
: public __is_destructible_safe<_Tp>::type
{
static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
"template argument must be a complete class or an unbounded array");
};
