[Ada] Crash when processing attribute Loop_Entry

[Arnaud Charlet <charlet at adacore dot com>]

This patch suppresses the resolution of the prefix of attribute Loop_Entry. The
resolution still takes place after Loop_Entry has been transformed into the
initialization expression of a constant. The delay ensures that any generated
checks or temporaries are inserted before the relocated prefix.

-------------
-- Sources --
-------------

--  main.adb:

with Ada.Text_IO; use Ada.Text_IO;

procedure Main is
   type Int_Array is array (Natural range <>) of Natural;

   procedure Process_Array (Obj : Int_Array) is
      Var : Natural := 0;
   begin
      for Index in Natural range Obj'Range loop
         Var := Var + 1;
         pragma Loop_Invariant (Obj (Obj'First + Var)'Loop_Entry >= 10);
      end loop;
      Put_Line (Integer'Image (Var));
   end Process_Array;

   X : Int_Array (1 .. 0);
begin
   Process_Array (X);
end Main;

----------------------------
-- Compilation and output --
----------------------------

$ gnatmake -q -gnat12 -gnata -gnatd.V main.adb
$ ./main
 0

Tested on x86_64-pc-linux-gnu, committed on trunk

2013-02-06  Hristian Kirtchev  <kirtchev@adacore.com>

	* sem_attr.adb (Resolve_Attribute): Do not resolve the prefix of
	Loop_Entry, instead wait until the attribute has been expanded. The
	delay ensures that any generated checks or temporaries are inserted
	before the relocated prefix.

Attachment: difs
Description: Text document