[Ada] Static matching of subtypes in Ada 2012

[Arnaud Charlet <charlet at adacore dot com>]

In Ada 2012, static matching of subtypes requires that the static predicates
that apply to the subtypes come from the same declaration.

Compiling predmatch.ads in Ada 2012 mode must yield:

   predmatch.ads:5:21: object subtype must statically match designated subtype
   predmatch.ads:12:22: object subtype must statically match designated subtype
   predmatch.ads:15:22: object subtype must statically match designated subtype

---
package Predmatch is
   type Int_Ref is access all Integer;
   subtype Even is Integer with Dynamic_predicate => Even mod 2 = 0;
   X1 : aliased Even;
   Ptr : Int_Ref := X1'access;  --  Illegal in Ada 2012

   subtype Little_Even is Integer
      with
        Static_Predicate  => Little_Even in 2 | 4 | 8 | 16;
   X2 : aliased Little_Even;

   Ptr2 : Int_Ref := X2'Access; -- illegal in Ada 2012

   type Pos_Ref is access all Positive;
   Ptr3 : Pos_Ref := X1'access;   --  Illegal in Ada 2005

   subtype Mult2 is Even;
   type Mult_Ref is access all Mult2;
   Ptr4 : Mult_Ref := X1'Access;  --  OK, same predicate
   
end Predmatch;

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

2012-05-15  Ed Schonberg  <schonberg@adacore.com>

	* sem_eval.adb (Subtypes_Statically_Match): In Ada 2012, static
	matching requires matching of static subtype predicates as well.

Attachment: difs
Description: Text document