[libcxx] Fix LWG Issue #2367 - Fixing std::tuple and std::pair's default constructors.
Summary: This patch implements the solution for LWG Issue #2367. See http://cplusplus.github.io/LWG/lwg-active.html#2367
Reviewers: mclow.lists, EricWF
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D13750
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@256325 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/utility b/include/utility
index 4d0191c..c9f5785 100644
--- a/include/utility
+++ b/include/utility
@@ -288,6 +288,12 @@
// pair(const pair&) = default;
// pair(pair&&) = default;
+#ifndef _LIBCPP_HAS_NO_DEFAULT_FUNCTION_TEMPLATE_ARGS
+ template <bool _Dummy = true, class = typename enable_if<
+ __dependent_type<is_default_constructible<_T1>, _Dummy>::value &&
+ __dependent_type<is_default_constructible<_T2>, _Dummy>::value
+ >::type>
+#endif
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR pair() : first(), second() {}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11