From 157a8f91bdf1216b48bb3a116cf06e54cd8e27a1 Mon Sep 17 00:00:00 2001
From: Marshall Clow <mclow.lists@gmail.com>
Date: Thu, 26 Jun 2014 01:07:56 +0000
Subject: [PATCH] Patch from Albert J. Wong to make type_traits take advantage
 of gcc intrinsics in 4.7 and later. No functionality change when using clang.

llvm-svn: 211755
---
 libcxx/include/__config    | 11 ++++++++++-
 libcxx/include/type_traits | 12 ++++++------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/libcxx/include/__config b/libcxx/include/__config
index c628524..981cc9f 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -339,7 +339,11 @@ typedef __char32_t char32_t;
 #endif
 
 #if __has_feature(underlying_type)
-#  define _LIBCXX_UNDERLYING_TYPE(T) __underlying_type(T)
+#  define _LIBCPP_UNDERLYING_TYPE(T) __underlying_type(T)
+#endif
+
+#if __has_feature(is_literal)
+#  define _LIBCPP_IS_LITERAL(T) __is_literal(T)
 #endif
 
 // Inline namespaces are available in Clang regardless of C++ dialect.
@@ -363,6 +367,11 @@ namespace std {
 
 #define _LIBCPP_NORETURN __attribute__((noreturn))
 
+#if _GNUC_VER >= 407
+#define _LIBCPP_UNDERLYING_TYPE(T) __underlying_type(T)
+#define _LIBCPP_IS_LITERAL(T) __is_literal_type(T)
+#endif
+
 #if !__EXCEPTIONS
 #define _LIBCPP_NO_EXCEPTIONS
 #endif
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index 6846af5..94a7362 100644
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -2971,8 +2971,8 @@ template <class _Tp> struct _LIBCPP_TYPE_VIS_ONLY is_pod
 // is_literal_type;
 
 template <class _Tp> struct _LIBCPP_TYPE_VIS_ONLY is_literal_type
-#if __has_feature(is_literal)
-    : public integral_constant<bool, __is_literal(_Tp)>
+#ifdef _LIBCPP_IS_LITERAL
+    : public integral_constant<bool, _LIBCPP_IS_LITERAL(_Tp)>
 #else
     : integral_constant<bool, is_scalar<typename remove_all_extents<_Tp>::type>::value ||
                               is_reference<typename remove_all_extents<_Tp>::type>::value>
@@ -3363,19 +3363,19 @@ struct __is_nothrow_swappable
 
 #endif  // __has_feature(cxx_noexcept)
 
-#ifdef _LIBCXX_UNDERLYING_TYPE
+#ifdef _LIBCPP_UNDERLYING_TYPE
 
 template <class _Tp>
 struct underlying_type
 {
-    typedef _LIBCXX_UNDERLYING_TYPE(_Tp) type;
+    typedef _LIBCPP_UNDERLYING_TYPE(_Tp) type;
 };
 
 #if _LIBCPP_STD_VER > 11
 template <class _Tp> using underlying_type_t = typename underlying_type<_Tp>::type;
 #endif
 
-#else  // _LIBCXX_UNDERLYING_TYPE
+#else  // _LIBCPP_UNDERLYING_TYPE
 
 template <class _Tp, bool _Support = false>
 struct underlying_type
@@ -3385,7 +3385,7 @@ struct underlying_type
                             "libc++ does not know how to use it.");
 };
 
-#endif // _LIBCXX_UNDERLYING_TYPE
+#endif // _LIBCPP_UNDERLYING_TYPE
 
 #ifndef _LIBCPP_HAS_NO_ADVANCED_SFINAE
 
-- 
2.7.4