re PR c++/36744 ([C++0x] function modifying argument received by-value affects…

re PR c++/36744 ([C++0x] function modifying argument received by-value affects caller's variable when passed as rvalue)

        PR c++/36744
        * tree.c (lvalue_p_1): Condition rvalue ref handling on
        treat_class_rvalues_as_lvalues, too.

From-SVN: r144091

gcc/cp/ChangeLog

+2009-02-10  Jason Merrill  <jason@redhat.com>
+
+	PR c++/36744
+	* tree.c (lvalue_p_1): Condition rvalue ref handling on
+	treat_class_rvalues_as_lvalues, too.
+
 2009-02-10  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/34397

gcc/cp/tree.c

@@ -82,7 +82,12 @@ lvalue_p_1 (tree ref,
 	  && TREE_CODE (ref) != PARM_DECL
 	  && TREE_CODE (ref) != VAR_DECL
 	  && TREE_CODE (ref) != COMPONENT_REF)
-	return clk_none;
+	{
+	  if (CLASS_TYPE_P (TREE_TYPE (TREE_TYPE (ref))))
+	    return treat_class_rvalues_as_lvalues ? clk_class : clk_none;
+	  else
+	    return clk_none;
+	}
 
       /* lvalue references and named rvalue references are lvalues.  */
       return clk_ordinary;

gcc/testsuite/ChangeLog

+2009-02-11  Jason Merrill  <jason@redhat.com>
+
+	PR c++/36744
+	* g++.dg/cpp0x/rv9p.C: New test.
+
 2009-02-10  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/aliasing3.adb: New test.

gcc/testsuite/g++.dg/cpp0x/rv9p.C

+// PR c++/36744
+// { dg-options "-std=c++0x" }
+// { dg-do run }
+
+struct S
+{
+  S(): i(2) {}
+  S(S const&s): i(s.i) {}
+  int i;
+};
+
+void f(S x) { x.i = 0; }
+
+extern "C" void abort (void);
+int main()
+{
+  S y;
+  f(static_cast<S&&>(y));
+  if (y.i != 2)
+    abort ();
+  return 0;
+}