[Ada] Support for renamings in aspects Depends and Global

[Arnaud Charlet <charlet at adacore dot com>]

This patch modifies the analysis of aspects Depends and Global. The machinery
can now process renamings of entire objects. Legal renamings are replaced by
the object they rename.

------------
-- Source --
------------

--  renamings.ads

package Renamings
  with Abstract_State => (Input_State with Volatile, Input)
is
   type Composite_Record is record
      Comp : Integer;
   end record;
   Rec : Composite_Record;
   type Composite_Array is array (1 .. 5) of Composite_Record;
   Arr : Composite_Array;

   --  "entire object" renamings

   Ren_1 : Composite_Record renames Rec;
   Ren_2 : Composite_Record renames Ren_1;

   --  illegal renamings

   Ren_3 : Integer renames Rec.Comp;
   Ren_4 : Composite_Record renames Arr (3);
   Ren_5 : Integer renames Arr (3).Comp;

   procedure OK_1
     with Global => Ren_1;
   procedure OK_2
     with Global => Ren_2;
   procedure Error_1
     with Global => (Rec, Ren_1, Ren_2);
   procedure Error_2
     with Global => (Ren_3, Ren_4, Ren_5);
end Renamings;

--  replacement.ads

package Replacement is
   Obj : Integer;
   Ren : Integer renames Obj;

   procedure OK_1
     with Global => Ren;
   function OK_2 return Integer
     with Depends => (OK_2'Result => Ren);
end Replacement;

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

$ gcc -c -gnat12 -gnatd.V renamings.ads
$ gcc -c -gnat12 -gnatd.V -gnatdg replacement.ads
renamings.ads:27:27: duplicate global item
renamings.ads:27:34: duplicate global item
renamings.ads:29:22: global item must denote variable or state
renamings.ads:29:29: global item must denote variable or state
renamings.ads:29:36: global item must denote variable or state
Source recreated from tree for Replacement (spec)

replacement_E : short_integer := 0;

package replacement is
   replacement__obj : integer;
   replacement__ren___XR_replacement__obj___XE : _renaming_type;
   replacement__ren : integer renames replacement__obj;
   procedure replacement__ok_1
     with global => ren;
   function replacement__ok_2 return integer
     with depends => (
             replacement__ok_2'result => replacement__obj);
   pragma depends ((
      replacement__ok_2'result => replacement__obj));
   pragma global (replacement__obj);
   freeze replacement__ok_1 []
end replacement;

cannot generate code for file replacement.ads (package spec)

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

2013-04-11  Hristian Kirtchev  <kirtchev@adacore.com>

	* sem_prag.adb (Analyze_Pragma): Both pragma Depends and Global can now
	support renamings of entire objects. Legal renamings are replaced by
	the object they rename.
	(Is_Renaming): New routine.

Attachment: difs
Description: Text document