Chris Jefferson found this bug to pair/tuple introduced by a recent change to the draft that I missed.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@126743 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__tuple b/include/__tuple
index 39e484a..b9f92c5 100644
--- a/include/__tuple
+++ b/include/__tuple
@@ -214,7 +214,7 @@
template <class _Tp0, class ..._Tp, class _Up0, class ..._Up>
struct __tuple_convertible_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> >
: public integral_constant<bool,
- is_convertible<_Tp0, _Up0>::value &&
+ is_constructible<_Up0, _Tp0>::value &&
__tuple_convertible_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {};
template <>