[Ada] Legality checks on uses of incomplete types.

[Arnaud Charlet]

This patch prevents compiler aborts in the presence of illegal uses of
incomplete types in various declarations, and rejects such uses in some
object renaming declaration.
Examples in ACATS test B3A1A02.

Tested on i686-pc-linux-gnu, committed on trunk

2008-08-06  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch3.adb (Analyze_Component_Declaration): Protect against misuse
	of incomplete type.

	* sem_ch8.adb (Analyze_Object_Renaming): Diagnose properly a renaming
	of a formal parameter of an incomplete type. Improve error message for
	other improper uses of incomplete types.

-------------- next part --------------
Index: sem_ch3.adb
===================================================================
--- sem_ch3.adb	(revision 138784)
+++ sem_ch3.adb	(working copy)
@@ -1667,6 +1667,7 @@
 
          if Ada_Version >= Ada_05
            and then Ekind (T) = E_Anonymous_Access_Type
+           and then Etype (E) /= Any_Type
          then
             --  Check RM 3.9.2(9): "if the expected type for an expression is
             --  an anonymous access-to-specific tagged type, then the object
Index: sem_ch8.adb
===================================================================
--- sem_ch8.adb	(revision 138765)
+++ sem_ch8.adb	(working copy)
@@ -832,8 +832,11 @@
       if Nkind (Nam) = N_Explicit_Dereference
         and then Ekind (Etype (T2)) = E_Incomplete_Type
       then
-         Error_Msg_N ("invalid use of incomplete type", Id);
+         Error_Msg_NE ("invalid use of incomplete type&", Id, T2);
          return;
+      elsif Ekind (Etype (T)) = E_Incomplete_Type then
+         Error_Msg_NE ("invalid use of incomplete type&", Id, T);
+         return;
       end if;
 
       --  Ada 2005 (AI-327)