From 0695aa3fcdbe1aba94e707d3125b5770e6b45ec9 Mon Sep 17 00:00:00 2001
From: Andreas Fabri <andreas.fabri@geometryfactory.com>
Date: Tue, 6 Sep 2016 11:18:22 +0200
Subject: [PATCH] Protect a counter shared by all threads using  atomic

---
 Nef_3/include/CGAL/Nef_3/SNC_indexed_items.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Nef_3/include/CGAL/Nef_3/SNC_indexed_items.h b/Nef_3/include/CGAL/Nef_3/SNC_indexed_items.h
index cc528b3c50a..326beea1a0b 100644
--- a/Nef_3/include/CGAL/Nef_3/SNC_indexed_items.h
+++ b/Nef_3/include/CGAL/Nef_3/SNC_indexed_items.h
@@ -22,6 +22,7 @@
 #define CGAL_NEF_SNC_INDEXED_ITEMS_H
 
 #include <CGAL/tss.h>
+#include <CGAL/atomic.h>
 
 #include <CGAL/Nef_3/Vertex.h>
 #include <CGAL/Nef_3/Halfedge.h>
@@ -42,7 +43,9 @@ class Index_generator {
  public:
   static int get_unique_index()
   {
-    CGAL_STATIC_THREAD_LOCAL_VARIABLE(int, unique, 0);
+    // initialized with 0
+    // http://en.cppreference.com/w/cpp/language/zero_initialization
+    static CGAL::cpp11::atomic<int> unique;
     return unique++;
   }
 };