[libcxx] LWG2485: get() should be overloaded for const tuple&&. Patch from K-Ballo.

Review: http://reviews.llvm.org/D14839
llvm-svn: 255941
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 545b8861fc40bb194d6e8daa382f9d6d4659a13b
diff --git a/include/array b/include/array
index 3609690..8866eaf 100644
--- a/include/array
+++ b/include/array
@@ -95,6 +95,7 @@
 template <size_t I, class T, size_t N> T& get(array<T, N>&) noexcept; // constexpr in C++14
 template <size_t I, class T, size_t N> const T& get(const array<T, N>&) noexcept; // constexpr in C++14
 template <size_t I, class T, size_t N> T&& get(array<T, N>&&) noexcept; // constexpr in C++14
+template <size_t I, class T, size_t N> const T&& get(const array<T, N>&&) noexcept; // constexpr in C++14
 
 }  // std
 
@@ -324,6 +325,15 @@
     return _VSTD::move(__a.__elems_[_Ip]);
 }
 
+template <size_t _Ip, class _Tp, size_t _Size>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const _Tp&&
+get(const array<_Tp, _Size>&& __a) _NOEXCEPT
+{
+    static_assert(_Ip < _Size, "Index out of bounds in std::get<> (const std::array &&)");
+    return _VSTD::move(__a.__elems_[_Ip]);
+}
+
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
 _LIBCPP_END_NAMESPACE_STD