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Correctly implement LWG 2049; std::is_destructible.

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@213163 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marshall Clow
2014-07-16 15:51:50 +00:00
parent 7ef03b79f9
commit 2b44e3dd49
5 changed files with 114 additions and 38 deletions
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64
include/type_traits
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@@ -1537,42 +1537,56 @@ template <class _Tp> struct _LIBCPP_TYPE_VIS_ONLY is_move_assignable
// is_destructible
template <class _Tp>
struct __destructible_test
{
_Tp __t;
};
// if it's a reference, return true
// if it's a function, return false
// if it's void, return false
// if it's an array of unknown bound, return false
// Otherwise, return "std::declval<_Up&>().~_Up()" is well-formed
// where _Up is remove_all_extents<_Tp>::type
template <typename _Tp>
struct __is_destructor_wellformed {
template <typename _Tp1, typename _Tp2 = decltype(_VSTD::declval<_Tp1&>().~_Tp1())>
static char __test (int);
template <typename _Tp1>
static __two __test (...);
static const bool value = sizeof(__test<_Tp>(12)) == sizeof(char);
};
template <class _Tp, bool>
struct __destructible_imp;
template <class _Tp>
decltype((_VSTD::declval<__destructible_test<_Tp> >().~__destructible_test<_Tp>(), true_type()))
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
__is_destructible_test(_Tp&&);
#else
__is_destructible_test(_Tp&);
#endif
false_type
__is_destructible_test(__any);
template <class _Tp, bool = is_void<_Tp>::value || is_abstract<_Tp>::value
|| is_function<_Tp>::value>
struct __destructible_imp
: public common_type
<
decltype(__is_destructible_test(declval<_Tp>()))
>::type {};
struct __destructible_imp<_Tp, false>
: public _VSTD::integral_constant<bool,
__is_destructor_wellformed<typename _VSTD::remove_all_extents<_Tp>::type>::value> {};
template <class _Tp>
struct __destructible_imp<_Tp, true>
: public false_type {};
: public _VSTD::true_type {};
template <class _Tp, bool>
struct __destructible_false;
template <class _Tp>
struct __destructible_false<_Tp, false> : public __destructible_imp<_Tp, _VSTD::is_reference<_Tp>::value> {};
template <class _Tp>
struct __destructible_false<_Tp, true> : public _VSTD::false_type {};
template <class _Tp>
struct is_destructible
: public __destructible_imp<_Tp> {};
: public __destructible_false<_Tp, _VSTD::is_function<_Tp>::value> {};
template <class _Tp>
struct is_destructible<_Tp[]>
: public false_type {};
: public _VSTD::false_type {};
template <>
struct is_destructible<void>
: public _VSTD::false_type {};
// move