re PR c++/51379 ([C++0x] [DR 799] reinterpret_cast is not particularly useful)

/cp
2012-01-01  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/51379
	* typeck.c (build_reinterpret_cast_1): Implement resolution of
	DR 799.

/testsuite
2012-01-01  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/51379
	* g++.dg/conversion/reinterpret4.C: New.
	* g++.dg/conversion/reinterpret1.C: Adjust.

From-SVN: r182775

gcc/cp/ChangeLog

-2011-12-31  Fabien Chêne  <fabien@gcc.gnu.org>
+2012-01-01  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/51379
+	* typeck.c (build_reinterpret_cast_1): Implement resolution of
+	DR 799.
+
+2012-01-01  Fabien Chêne  <fabien@gcc.gnu.org>
 
 	* parser.c (cp_parser_using_declaration): Add a warning about
 	deprecated access declarations when no errors were encountered

gcc/cp/typeck.c

@@ -6203,6 +6203,11 @@ build_reinterpret_cast_1 (tree type, tree expr, bool c_cast_p,
   else if (TYPE_PTR_P (type) && INTEGRAL_OR_ENUMERATION_TYPE_P (intype))
     /* OK */
     ;
+  else if ((INTEGRAL_OR_ENUMERATION_TYPE_P (type)
+	    || TYPE_PTR_P (type) || TYPE_PTR_TO_MEMBER_P (type))
+	   && same_type_p (type, intype))
+    /* DR 799 */
+    return fold_if_not_in_template (build_nop (type, expr));
   else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
 	   || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
     return fold_if_not_in_template (build_nop (type, expr));

gcc/testsuite/ChangeLog

 2012-01-01  Paolo Carlini  <paolo.carlini@oracle.com>
 
+	PR c++/51379
+	* g++.dg/conversion/reinterpret4.C: New.
+	* g++.dg/conversion/reinterpret1.C: Adjust.
+
+2012-01-01  Paolo Carlini  <paolo.carlini@oracle.com>
+
 	* g++.dg/cpp0x/constexpr-delegating2.C: Add missing piece.
 
 2012-01-01  Fabien Chêne  <fabien@gcc.gnu.org>

gcc/testsuite/g++.dg/conversion/reinterpret1.C

@@ -3,4 +3,4 @@
 struct Y { Y(int &); };
 
 int v;
-Y y1(reinterpret_cast<int>(v));  // { dg-error "" }
+Y y1(reinterpret_cast<int>(v));

gcc/testsuite/g++.dg/conversion/reinterpret4.C

+// PR c++/51379
+
+unsigned long t1 = 1;
+unsigned long t2 = reinterpret_cast<unsigned long>(t1);