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Date: Sun, 19 Apr 2020 15:31:13 -0700 (PDT)
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Subject: Re: GNAT CE 2019 bug: Predicate check not performed
From: Anh Vo <anhvofrcaus@gmail.com>
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Xref: reader01.eternal-september.org comp.lang.ada:58422
Date: 2020-04-19T15:31:13-07:00
List-Id: <comp.lang.ada>

On Sunday, April 19, 2020 at 2:28:18 AM UTC-7, AdaMagica wrote:
> The problem is with GNAT CE 2019.
> GNAT CE 2018 was correct.
> ------------------------------------------------
> with Ada.Text_IO;
> use  Ada.Text_IO;
> with Ada.Assertions;
> use  Ada.Assertions;
>=20
> procedure Ass is
>=20
>   pragma Assertion_Policy (Check);
>=20
>   subtype String_5 is String with Dynamic_Predicate =3D> String_5'First =
=3D 5;
>=20
>   procedure P (X: String_5) is
>   begin
>     Put_Line ("P expects 5:" & X'First'Image);
>   end P;
>=20
>   procedure Q (X: String) is
>   begin
>     P (X);  -- Why no predicate check here?
>   end Q;
>=20
>   S: constant String :=3D "Lady Ada";
>=20
> begin
>=20
>   begin
>     Q (S);  -- prints 1, expected Assertion_Error
>     Put_Line ("Problem Q: Assertion_Error not raised.");
>   exception
>     when Assertion_Error =3D> Put_Line ("Q: Assertion_Error raised as exp=
ected.");
>   end;
>=20
>   begin
>     P (S);  -- Assertion_Error raised here
>     Put_Line ("Problem P: Assertion_Error not raised.");
>   exception
>     when Assertion_Error =3D> Put_Line ("P: Assertion_Error raised as exp=
ected.");
>   end;
>=20
> end Ass;
> ---------------------
> Result GNAT CE 2018
> C:\Users\Grein\Documents\Christoph\Ada\Spielplatz\ausprobieren.exe
> Q: Assertion_Error raised as expected.
> P: Assertion_Error raised as expected.
> [2020-04-18 19:33:34] process terminated successfully, elapsed time: 07.4=
7s
> Result GNAT CE 2019
> C:\Users\Grein\Documents\Christoph\Ada\Spielplatz\ausprobieren.exe
> P expects 5: 1
> Problem Q: Assertion_Error not raised.
> P: Assertion_Error raised as expected.
> [2020-04-18 19:58:20] process terminated successfully, elapsed time: 04.2=
5s

It takes time to look thru the LRM to if this behavior is expected or not. =
However if String_5 is changed to type and lines 19 and 34 are adjusted for=
 compilation, then it behaves as in GNAT CE 2018. By the way, GNAT Communit=
y 2019 on Windows 10 is for this check.