From 98a4949e960a855ebeb69ba71b4894a8d155018d Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Mon, 18 Jan 2016 15:51:34 +0100
Subject: [PATCH] Better version of <CGAL/atomic.h>

The implementation is simplified.

If no implementation of `::atomic` is available, `CGAL_NO_ATOMIC` is
defined to an error message (replaced the `#error`).
---
 Installation/include/CGAL/atomic.h | 47 +++++++++++++++++-------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/Installation/include/CGAL/atomic.h b/Installation/include/CGAL/atomic.h
index 157cca70c26..2ae15fa616e 100644
--- a/Installation/include/CGAL/atomic.h
+++ b/Installation/include/CGAL/atomic.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2016 GeometryFactory (France)
+// Copyright (c) 2016 GeometryFactory Sarl (France)
 //  All rights reserved.
 //
 // This file is part of CGAL (www.cgal.org); you can redistribute it and/or
@@ -21,29 +21,36 @@
 #include <CGAL/config.h>
 
 #ifdef CGAL_HAS_THREADS
+
 #  ifdef CGAL_CAN_USE_CXX11_ATOMIC
 #    include <atomic>
-
-     namespace CGAL {
-       namespace cpp11 {
-         using std::atomic;
-       }
-     }
-
+#    define CGAL_ATOMIC_NS std
 #  else // not CGAL_CAN_USE_CXX11_ATOMIC
-#    if BOOST_VERSION < 105300
-#      error Boost.Atomic was introduced in Boost-1.53
-#    endif
-#    include <boost/thread/atomic.hpp>
-
-     namespace CGAL {
-       namespace cpp11 {
-         using boost::atomic;
-       }
-     }
-
+#    if BOOST_VERSION >= 105300
+#      include <boost/thread/atomic.hpp>
+#      define CGAL_ATOMIC_NS boost
+#    else // BOOST_VERSION < 105300
+#      define CGAL_NO_ATOMIC "Boost.Atomic was introduced in Boost-1.53"
+#    endif // BOOST_VERSION < 105300
 #  endif // not CGAL_CAN_USE_CXX11_ATOMIC
+
+#  ifndef CGAL_NO_ATOMIC
+   namespace CGAL {
+     namespace cpp11 {
+       using CGAL_ATOMIC_NS ::atomic;
+
+       using CGAL_ATOMIC_NS ::memory_order_relaxed;
+       using CGAL_ATOMIC_NS ::memory_order_consume;
+       using CGAL_ATOMIC_NS ::memory_order_acquire;
+       using CGAL_ATOMIC_NS ::memory_order_release;
+       using CGAL_ATOMIC_NS ::memory_order_acq_rel;
+       using CGAL_ATOMIC_NS ::memory_order_seq_cst;
+
+       using CGAL_ATOMIC_NS ::atomic_thread_fence;
+     }
+   }
+#  endif // CGAL_ATOMIC_NS
+
 #endif // CGAL_HAS_THREADS
 
 #endif // CGAL_ATOMIC_H
-