Ada.Strings.Fixed.Count raises Storage_Error

[Xavier Petit <xpetit@becoast.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