sem_attr.adb: add guard to previous patch.

2008-05-27  Ed Schonberg  <schonberg@adacore.com>

	* sem_attr.adb: add guard to previous patch.

From-SVN: r135977

gcc/ada/sem_attr.adb

@@ -5234,6 +5234,7 @@ package body Sem_Attr is
          --  subtype then get the type from the initial value. If the value has
          --  been expanded into assignments, there is no expression and the
          --  attribute reference remains dynamic.
+
          --  We could do better here and retrieve the type ???
 
          if Ekind (P_Entity) = E_Constant
@@ -8094,9 +8095,10 @@ package body Sem_Attr is
                --  the slice is non-null. That is because a null slice can have
                --  an out of bounds index value.
 
-               --  Right now, gigi blows up if given 'Address on a slice, and
-               --  this covers up that bug in one case, but the bug is likely
-               --  still there in the cases not transformed by this code ???
+               --  Right now, gigi blows up if given 'Address on a slice as a
+               --  result of some incorrect freeze nodes generated by the front
+               --  end, and this covers up that bug in one case, but the bug is
+               --  likely still there in the cases not handled by this code ???
 
                --  It's not clear what 'Address *should* return for a null
                --  slice with out of bounds indexes, this might be worth an ARG
@@ -8127,7 +8129,9 @@ package body Sem_Attr is
                           Prefix => (New_Occurrence_Of (Entity (D), Loc)),
                           Attribute_Name => Name_First);
 
-                  elsif Not_Null_Range (Low_Bound (D), High_Bound (D)) then
+                  elsif Nkind (D) = N_Range
+                    and then Not_Null_Range (Low_Bound (D), High_Bound (D))
+                  then
                      Lo := Low_Bound (D);
 
                   else