added an auto_ptr & constructor to shared_count

[SVN r12623]

include/boost/detail/shared_count.hpp

@@ -16,6 +16,13 @@
 //  warranty, and with no claim as to its suitability for any purpose.
 //
 
+#include <boost/config.hpp>
+
+#ifndef BOOST_NO_AUTO_PTR
+# include <memory>
+#endif
+
+#include <boost/checked_delete.hpp>
 #include <boost/detail/atomic_count.hpp>
 
 namespace boost
@@ -160,6 +167,18 @@ public:
         }
     }
 
+#ifndef BOOST_NO_AUTO_PTR
+
+    // auto_ptr<Y> is special cased to provide the strong guarantee
+
+    template<typename Y>
+    explicit shared_count(std::auto_ptr<Y> & r): pi_(new counted_base_impl< Y *, checked_deleter<Y> >(r.get(), checked_deleter<Y>(), 1, 1))
+    {
+        r.release();
+    }
+
+#endif 
+
     ~shared_count() // nothrow
     {
         pi_->release();