trans.c (gnat_to_gnu): Try again to translate the prefix after the field if it is incomplete.

2017-09-06  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc-interface/trans.c (gnat_to_gnu) <N_Selected_Component>: Try
	again to translate the prefix after the field if it is incomplete.

From-SVN: r251788

gcc/ada/ChangeLog

+2017-09-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+        * gcc-interface/trans.c (gnat_to_gnu) <N_Selected_Component>: Try
+        again to translate the prefix after the field if it is incomplete.
+
 2017-09-06  Bob Duff  <duff@adacore.com>
 
 	* exp_util.adb (Is_Displace_Call): Make sure it works for indirect

gcc/ada/gcc-interface/trans.c

@@ -6465,6 +6465,17 @@ gnat_to_gnu (Node_Id gnat_node)
 	  {
 	    tree gnu_field = gnat_to_gnu_field_decl (gnat_field);
 
+	    /* If the prefix has incomplete type, try again to translate it.
+	       The idea is that the translation of the field just above may
+	       have completed it through gnat_to_gnu_entity, in case it is
+	       the dereference of an access to Taft Amendment type used in
+	       the instantiation of a generic body from an external unit.  */
+	    if (!COMPLETE_TYPE_P (TREE_TYPE (gnu_prefix)))
+	      {
+		gnu_prefix = gnat_to_gnu (gnat_prefix);
+		gnu_prefix = maybe_implicit_deref (gnu_prefix);
+	      }
+		
 	    gnu_result
 	      = build_component_ref (gnu_prefix, gnu_field,
 				     (Nkind (Parent (gnat_node))