fix PR c++/19531: NRV is performed on volatile temporary

Co-Authored-By: Mark Mitchell <mark@codesourcery.com>

From-SVN: r129792

gcc/cp/ChangeLog

+2007-10-31 Christian Bruel  <christian.bruel@st.com>
+           Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/19531
+	* cp/typeck.c (check_return_expr): Don't set named_return_value_okay_p
+	if retval is volatile. 
+	
 2007-10-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/33616

gcc/cp/typeck.c

@@ -6744,7 +6744,9 @@ check_return_expr (tree retval, bool *no_warning)
         function.  */
      && same_type_p ((TYPE_MAIN_VARIANT (TREE_TYPE (retval))),
                      (TYPE_MAIN_VARIANT
-                      (TREE_TYPE (TREE_TYPE (current_function_decl))))));
+                      (TREE_TYPE (TREE_TYPE (current_function_decl)))))
+     /* And the returned value must be non-volatile.  */
+     && ! TYPE_VOLATILE (TREE_TYPE (retval)));
      
   if (fn_returns_value_p && flag_elide_constructors)
     {

gcc/testsuite/ChangeLog

+2007-10-31  Christian Bruel  <christian.bruel@st.com>
+
+	PR c++/19531
+	* g++.dg/opt/nrv8.C: New.
+	
 2007-10-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/33709

gcc/testsuite/g++.dg/opt/nrv8.C

+// PR optimization/19531
+// forbids NRV on volatile return value.
+// { dg-options -O2 }
+// { dg-do run }
+
+extern "C" { void abort(); }
+
+struct A
+{
+  int d;
+
+  A ()                     { d = 123; }
+  A (const A & o)          { d = o.d;  }
+  A (volatile const A & o) { d = o.d + 2; }
+};
+
+A bar()
+{
+  volatile A l;
+  return l;
+}
+
+main()
+{
+  A a = bar ();
+
+  if (a.d != 125)
+    abort();
+
+  return 0;
+}