From 7f2aae99374591badceb805a7cc9b2d17ceecc96 Mon Sep 17 00:00:00 2001
From: Howard Hinnant <hhinnant@apple.com>
Date: Fri, 3 Sep 2010 23:03:25 +0000
Subject: [PATCH] Configure libc++ to recognize and use inline namespaces for
 clang.  Many, many thanks to Sebastian Redl for implementing it in clang, and
 to Daniel Dunbar for rattling my cage about it.  This is huge for libc++. 
 Thanks to you both\!

llvm-svn: 113026
---
 libcxx/include/__config | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/libcxx/include/__config b/libcxx/include/__config
index 2bba0e96cb3a..9511ee1b8f2c 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -95,9 +95,24 @@
 #endif
 
 #define _LIBCPP_HAS_NO_ADVANCED_SFINAE
-#define _LIBCPP_HAS_NO_STRONG_USING
 #define _LIBCPP_HAS_NO_TEMPLATE_ALIASES
 
+#if __has_feature(cxx_inline_namespaces)
+#define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {inline namespace _LIBCPP_NAMESPACE {
+#define _LIBCPP_END_NAMESPACE_STD  } }
+#define _STD std::_LIBCPP_NAMESPACE
+
+namespace std {
+inline namespace _LIBCPP_NAMESPACE {
+}
+using namespace _LIBCPP_NAMESPACE;
+}
+#else  // __has_feature(cxx_inline_namespaces)
+#define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {
+#define _LIBCPP_END_NAMESPACE_STD }
+#define _STD std
+#endif  // __has_feature(cxx_inline_namespaces)
+
 #ifndef __GXX_EXPERIMENTAL_CXX0X__
 
 #define _LIBCPP_HAS_NO_DECLTYPE
@@ -181,13 +196,6 @@
 
 #endif  // __GXX_EXPERIMENTAL_CXX0X__
 
-#endif  // defined(__GNUC__)
-
-#ifdef _LIBCPP_HAS_NO_STRONG_USING
-#define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {
-#define _LIBCPP_END_NAMESPACE_STD }
-#define _STD std
-#else  // _LIBCPP_HAS_NO_STRONG_USING
 #define _LIBCPP_BEGIN_NAMESPACE_STD namespace std { namespace _LIBCPP_NAMESPACE {
 #define _LIBCPP_END_NAMESPACE_STD  } }
 #define _STD std::_LIBCPP_NAMESPACE
@@ -198,7 +206,7 @@ namespace _LIBCPP_NAMESPACE {
 using namespace _LIBCPP_NAMESPACE __attribute__((__strong__));
 }
 
-#endif  // _LIBCPP_HAS_NO_STRONG_USING
+#endif  // defined(__GNUC__)
 
 #ifdef _LIBCPP_HAS_NO_UNICODE_CHARS
 typedef unsigned short char16_t;