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From: Gautier write-only <gautier_niouzes@hotmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Inferring array index type from array object
Date: Wed, 23 Jun 2010 06:12:17 -0700 (PDT)
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Date: 2010-06-23T06:12:17-07:00
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Perhaps empty ranges have played a role for designers not going too
far into defining what you would like (some "subtype S_range is
S'Range", or "type S_range is new S'Range" ?) ?

procedure String_range is
  subtype Index_empty is Positive range 1..0;
  I1: Index_empty:= Index_empty'First;
  --
  S: constant String:= "";
  I2 : Positive range S'Range:= S'First;
begin
  null;
end;

There, GNAT produces a Constraint_Error for any of I1 or I2, on the :=
lines.

G.