Merge pull request #6 from K-ballo/ref-do-not-bind-to-temporaries

Disable binding ref to temporaries when rvalue references are supported

include/boost/core/ref.hpp

@@ -20,6 +20,7 @@
 //
 //  Copyright (C) 2014 Glen Joseph Fernandes
 //  glenfe at live dot com
+//  Copyright (C) 2014 Agustin Berge
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -65,6 +66,14 @@ public:
     */
     BOOST_FORCEINLINE explicit reference_wrapper(T& t): t_(boost::addressof(t)) {}
 
+# if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+    /**
+     @remark Construction from a temporary object is disabled.
+    */
+    BOOST_DELETED_FUNCTION(reference_wrapper(T&& t))
+public:
+# endif
+
     /**
      @return The stored reference.
      @remark Does not throw.
@@ -112,6 +121,15 @@ template<class T> BOOST_FORCEINLINE reference_wrapper<T> BOOST_REF_CONST ref( T
     return reference_wrapper<T>(t);
 }
 
+/**
+ @return `ref(t.get())`
+ @remark Does not throw.
+*/
+template<class T> BOOST_FORCEINLINE reference_wrapper<T> BOOST_REF_CONST ref( reference_wrapper<T> t )
+{
+    return reference_wrapper<T>(t.get());
+}
+
 // cref
 
 /**
@@ -123,8 +141,45 @@ template<class T> BOOST_FORCEINLINE reference_wrapper<T const> BOOST_REF_CONST c
     return reference_wrapper<T const>(t);
 }
 
+/**
+ @return `cref(t.get())`
+ @remark Does not throw.
+*/
+template<class T> BOOST_FORCEINLINE reference_wrapper<T const> BOOST_REF_CONST cref( reference_wrapper<T> t )
+{
+    return reference_wrapper<T const>(t.get());
+}
+
 # undef BOOST_REF_CONST
 
+# if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+
+/**
+ @cond
+*/
+#  if defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
+#   define BOOST_REF_DELETE
+#  else
+#   define BOOST_REF_DELETE = delete
+#  endif
+/**
+ @endcond
+*/
+
+/**
+ @remark Construction from a temporary object is disabled.
+*/
+template<class T> void ref(T const&& t) BOOST_REF_DELETE;
+
+/**
+ @remark Construction from a temporary object is disabled.
+*/
+template<class T> void cref(T const&& t) BOOST_REF_DELETE;
+
+# undef BOOST_REF_DELETE
+
+# endif
+
 // is_reference_wrapper
 
 /**

test/Jamfile.v2

@@ -19,6 +19,9 @@ compile-fail checked_delete_fail2.cpp ;
 
 compile ref_ct_test.cpp ;
 run ref_test.cpp ;
+compile-fail ref_rv_fail1.cpp ;
+compile-fail ref_rv_fail2.cpp ;
+compile-fail ref_rv_fail3.cpp ;
 
 run eif_constructors.cpp ;
 run eif_dummy_arg_disambiguation.cpp ;

test/ref_rv_fail1.cpp

@@ -0,0 +1,21 @@
+// Copyright 2002-2004 David Abrahams and Aleksey Gurtovoy
+// Copyright 2014 Agustin Berge
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/ref.hpp>
+
+# if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+
+int main()
+{
+  boost::reference_wrapper<int const> r(1); // this should produce an ERROR
+
+  return 0;
+}
+
+# else
+#   error To fail, this test requires rvalue references
+# endif

test/ref_rv_fail2.cpp

@@ -0,0 +1,15 @@
+// Copyright 2002-2004 David Abrahams and Aleksey Gurtovoy
+// Copyright 2014 Agustin Berge
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/ref.hpp>
+
+int main()
+{
+  boost::reference_wrapper<int> r = boost::ref(2); // this should produce an ERROR
+
+  return 0;
+}

test/ref_rv_fail3.cpp

@@ -0,0 +1,25 @@
+// Copyright 2002-2004 David Abrahams and Aleksey Gurtovoy
+// Copyright 2014 Agustin Berge
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/ref.hpp>
+
+# if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+
+struct X {};
+
+X const crv() { return X(); }
+
+int main()
+{
+  boost::reference_wrapper<X const> r = boost::ref(crv()); // this should produce an ERROR
+
+  return 0;
+}
+
+# else
+#   error To fail, this test requires rvalue references
+# endif