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From: "G.B." <bauhaus@futureapps.invalid>
Newsgroups: comp.lang.ada
Subject: Re: SPARK internal error?
Date: Tue, 03 Mar 2015 13:58:16 +0100
Organization: A noiseless patient Spider
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Date: 2015-03-03T13:58:16+01:00
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On 03.03.15 10:54, Maciej Sobczak wrote:
>      procedure Sort (A : in out My_Array) is
>      begin
>          for I in A'Range loop
>              Min_To_Left (A (I .. A'Last));
>
>              pragma Loop_Invariant
>                  (for all J in I .. A'Last =>
>                          A (I) <= A (J));
>          end loop;
>      end Sort;

The following passes and makes gnatprove produce
warning addressing range/pre/post/loop_invariant:

     procedure Sort (A : in out My_Array) is
     begin
         for I in A'Range loop
             declare
                 X : My_Array (I .. A'Last) := (others => 0);
             begin
                 for K in I .. A'Last loop
                     X (K) := A (K);
                 end loop;
                 Min_To_Left (X);
                 for K in I .. A'Last loop
                     A (K) := X (K);
                 end loop;
             end;

             pragma Loop_Invariant
                 ((for all J in I .. A'Last =>
                         A (I) <= A (J)));
         end loop;
     end Sort;