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-rw-r--r--contrib/libc++/include/type_traits17
1 files changed, 12 insertions, 5 deletions
diff --git a/contrib/libc++/include/type_traits b/contrib/libc++/include/type_traits
index f467735..8612e57 100644
--- a/contrib/libc++/include/type_traits
+++ b/contrib/libc++/include/type_traits
@@ -842,7 +842,16 @@ template <class _T1, class _T2> struct _LIBCPP_TYPE_VIS_ONLY is_convertible
namespace __is_convertible_imp
{
-template <class _Tp> char __test(_Tp);
+template <class _Tp> void __test_convert(_Tp);
+
+template <class _From, class _To, class = void>
+struct __is_convertible_test : public false_type {};
+
+template <class _From, class _To>
+struct __is_convertible_test<_From, _To,
+ decltype(__test_convert<_To>(_VSTD::declval<_From>()))> : public true_type
+{};
+
template <class _Tp> __two __test(...);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
template <class _Tp> _Tp&& __source();
@@ -877,10 +886,8 @@ template <class _T1, class _T2,
unsigned _T2_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T2>::value>
struct __is_convertible
: public integral_constant<bool,
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
- sizeof(__is_convertible_imp::__test<_T2>(__is_convertible_imp::__source<_T1>())) == 1
-#else
- sizeof(__is_convertible_imp::__test<_T2>(__is_convertible_imp::__source<_T1>())) == 1
+ __is_convertible_imp::__is_convertible_test<_T1, _T2>::value
+#if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
&& !(!is_function<_T1>::value && !is_reference<_T1>::value && is_reference<_T2>::value
&& (!is_const<typename remove_reference<_T2>::type>::value
|| is_volatile<typename remove_reference<_T2>::type>::value)
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