trans.c (Attribute_to_gnu): Do not strip conversions around prefixes that are not references.

	* gcc-interface/trans.c (Attribute_to_gnu) <Attr_Address>: Do not strip
	conversions around prefixes that are not references.

From-SVN: r251704

gcc/ada/ChangeLog

 2017-09-05  Eric Botcazou  <ebotcazou@adacore.com>
 
+	* gcc-interface/trans.c (Attribute_to_gnu) <Attr_Address>: Do not strip
+	conversions around prefixes that are not references.
+
+2017-09-05  Eric Botcazou  <ebotcazou@adacore.com>
+
 	* gcc-interface/utils.c (unchecked_convert): When the result type is a
 	non-biased integral type with size 0, set the result to 0 directly.
 

gcc/ada/gcc-interface/trans.c

@@ -1629,10 +1629,14 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute)
 
     case Attr_Address:
     case Attr_Unrestricted_Access:
-      /* Conversions don't change addresses but can cause us to miss the
-	 COMPONENT_REF case below, so strip them off.  */
-      gnu_prefix = remove_conversions (gnu_prefix,
-				       !Must_Be_Byte_Aligned (gnat_node));
+      /* Conversions don't change the address of references but can cause
+	 build_unary_op to miss the references below, so strip them off.
+	 On the contrary, if the address-of operation causes a temporary
+	 to be created, then it must be created with the proper type.  */
+      gnu_expr = remove_conversions (gnu_prefix,
+				     !Must_Be_Byte_Aligned (gnat_node));
+      if (REFERENCE_CLASS_P (gnu_expr))
+	gnu_prefix = gnu_expr;
 
       /* If we are taking 'Address of an unconstrained object, this is the
 	 pointer to the underlying array.  */