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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
 =?utf-8?Q?=29?=
 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: GNAT 4.8 bug with subtype predicate
Date: Thu, 07 Mar 2013 03:11:55 +0100
Organization: Ada @ Home
Message-ID: <op.wtj0d51hule2fv@cardamome>
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Date: 2013-03-07T03:11:55+01:00
List-Id: <comp.lang.ada>

Just out of curiosity, tell me what you get if you try this in a package=
  =

specification:


     type T is range 1 .. 100
        with Dynamic_Predicate =3D> T not in 10 .. 15;

     function F (I : T) return Positive
        is (Positive'Val (T'Pos (I)));


Do you get an error from GNAT complaining about =E2=80=9Cinvalid use of =
subtype  =

mark in expression or call=E2=80=9D on the line holding the predicate?

That's what I get with GNAT from GCC 4.8.

The error disappears if I change `F` into:


     function F (I : T) return Positive
        is (Positive (I));


But that may not be allowed, if say T is a range, and the function retur=
ns  =

Character (the direct conversion is not allowed, and requires 'Val/'Pos)=
.

The error also disappears if I only have this in the public part


     function F (I : T) return Positive;


=E2=80=A6then have this in the private part:


     function F (I : T) return Positive
        is (Positive'Val (T'Pos (I)));


-- =

=E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [1]
=E2=80=9CStructured Programming supports the law of the excluded muddle.=
=E2=80=9D [1]
[1]: Epigrams on Programming =E2=80=94 Alan J. =E2=80=94 P. Yale Univers=
ity