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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada.Strings.Fixed.Count raises Storage_Error
Date: Thu, 12 May 2016 17:56:36 -0500
Organization: JSA Research & Innovation
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Xref: news.eternal-september.org comp.lang.ada:30396
Date: 2016-05-12T17:56:36-05:00
List-Id: <comp.lang.ada>

Well, *anything* in Ada is allowed to raise Storage_Error (even the null 
statement!), so formally the behavior is correct.

OTOH, there doesn't seem to be any actual running out of memory here, so it 
is most likely a bug (especially as the other responses suggest that the 
main problem is that the checks are suppressed in the library code). And 
it's unlikely that the implementer expected this code to raise 
Storage_Error.

                            Randy.

"Xavier Petit" <xpetit@becoast.fr> wrote in message 
news:57346ac8$0$4570$426a74cc@news.free.fr...
> Hello, I would like to know if it is normal or a known bug.
>
> function Count
>   (Source  : String;
>    Pattern : String;
>    Mapping : Maps.Character_Mapping := Maps.Identity) return Natural;
>
> When Source'Last = Positive'Last and Pattern'Length = 1, I get
> Storage_Error, it seems this is because the checks are suppressed in
> this GNAT runtime function ? So with checks it would result a
> Constraint_Error ?
>
> Internally, the exit condition is tested after the index incrementation, 
> so in this specific case the "Ind" index tries to store Positive'Last + 1. 
> I think.
>
> Here the code :
>
> with Ada.Strings.Fixed, Ada.Integer_Text_IO;
> use  Ada.Strings.Fixed, Ada.Integer_Text_IO;
>
> procedure Test_Count is
>    S : constant String (Positive'Last - 2 .. Positive'Last) := "Ada";
> begin
>    Put (Count (Source => S,                         Pattern => "AA"));
>    Put (Count (Source => S (S'First .. S'Last - 1), Pattern => "A"));
>    Put (Count (Source => S,                         Pattern => "A"));
> end;
>
> Output on gnat-gcc 5.3.1 :
>
>           0          1
>
> raised STORAGE_ERROR : stack overflow or erroneous memory access
>
>
> Thanks by advance
>
> -- 
> Xavier Petit