[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/utility b/include/utility
index 8b37661..4d0191c 100644
--- a/include/utility
+++ b/include/utility
@@ -120,15 +120,34 @@
     typename tuple_element<I, pair<T1, T2> >::type&&
     get(pair<T1, T2>&&) noexcept; // constexpr in C++14
 
+template<size_t I, class T1, class T2>
+    const typename tuple_element<I, pair<T1, T2> >::type&&
+    get(const pair<T1, T2>&&) noexcept; // constexpr in C++14
+
 template<class T1, class T2>
     constexpr T1& get(pair<T1, T2>&) noexcept; // C++14
 
-template<size_t I, class T1, class T2>
+template<class T1, class T2>
     constexpr const T1& get(const pair<T1, T2>&) noexcept; // C++14
 
-template<size_t I, class T1, class T2>
+template<class T1, class T2>
     constexpr T1&& get(pair<T1, T2>&&) noexcept; // C++14
 
+template<class T1, class T2>
+    constexpr const T1&& get(const pair<T1, T2>&&) noexcept; // C++14
+
+template<class T1, class T2>
+    constexpr T1& get(pair<T2, T1>&) noexcept; // C++14
+
+template<class T1, class T2>
+    constexpr const T1& get(const pair<T2, T1>&) noexcept; // C++14
+
+template<class T1, class T2>
+    constexpr T1&& get(pair<T2, T1>&&) noexcept; // C++14
+
+template<class T1, class T2>
+    constexpr const T1&& get(const pair<T2, T1>&&) noexcept; // C++14
+
 // C++14
 
 template<class T, T... I>
@@ -560,6 +579,12 @@
     _T1&&
     get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
 
+    template <class _T1, class _T2>
+    static
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    const _T1&&
+    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T1>(__p.first);}
+
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 };
 
@@ -586,6 +611,12 @@
     _T2&&
     get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
 
+    template <class _T1, class _T2>
+    static
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    const _T2&&
+    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T2>(__p.second);}
+
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 };
 
@@ -615,6 +646,14 @@
     return __get_pair<_Ip>::get(_VSTD::move(__p));
 }
 
+template <size_t _Ip, class _T1, class _T2>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
+get(const pair<_T1, _T2>&& __p) _NOEXCEPT
+{
+    return __get_pair<_Ip>::get(_VSTD::move(__p));
+}
+
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
 #if _LIBCPP_STD_VER > 11
@@ -641,6 +680,13 @@
 
 template <class _T1, class _T2>
 inline _LIBCPP_INLINE_VISIBILITY
+constexpr _T1 const && get(pair<_T1, _T2> const&& __p) _NOEXCEPT
+{
+    return __get_pair<0>::get(_VSTD::move(__p));
+}
+
+template <class _T1, class _T2>
+inline _LIBCPP_INLINE_VISIBILITY
 constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
 {
     return __get_pair<1>::get(__p);
@@ -660,6 +706,13 @@
     return __get_pair<1>::get(_VSTD::move(__p));
 }
 
+template <class _T1, class _T2>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _T1 const && get(pair<_T2, _T1> const&& __p) _NOEXCEPT
+{
+    return __get_pair<1>::get(_VSTD::move(__p));
+}
+
 #endif
 
 #if _LIBCPP_STD_VER > 11