[Ada] Attributes of arrays with an index type derived from a formal type

[Arnaud Charlet <charlet at adacore dot com>]

The attributes of formal discrete types, and of arrays whose indices are
formal types, are not static and cannot be constant-folded. The same is true
if an index type is derived from a formal type. The check for types derived
from formal types was missing, leading to improper static evaluation..

The following must compile and execute quietly:

with G1;
procedure Q is
   type Indx is range 1 .. 10;
   package Inst is new G1 (Indx);
   use Inst;
   Obj : R := ((others => 0), 10);
begin
   if not Is_Full (Obj) then
      raise Program_Error;
   end if;
end;
---
generic
   type Ix is range <>;
package G1 is
   type Iterator is new Ix;
   type Arr is array (Iterator) of integer;
   type R is record
      Nodes : Arr;
      Count : Positive;
   end record;

   function Is_Full (It : R) return Boolean;
end G1;
---
package body G1 is
   function Is_Full (It : R) return Boolean is
   begin
      return It.Count = It.Nodes'Length;
   end Is_Full;
end G1;

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

2010-06-23  Ed Schonberg  <schonberg@adacore.com>

	* sem_attr.adb (Eval_Attribute): If the prefix is an array, the
	attribute cannot be constant-folded if an index type is a formal type,
	or is derived from one.
	* checks.adb (Determine_Range): ditto.

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