Re: Warnings about hiding

[Adam Beneschan <adam@irvine.com>]

On Oct 8, 5:47 am, Julian Leyh <jul...@vgai.de> wrote:
> Hi,
>
> "-gnatwh" activates warnings on hiding declarations. But sometimes,
> hiding is necessary.
>
> For example, consider this (Controlled type with it's own comparison
> operator and finalize procedure, you can reproduce the errors using
> these ads files):
>
> $ cat foo.ads
> with Ada.Finalization;
> package foo is
>    type Foobar is new Ada.Finalization.Controlled with null record;
>    function "=" (L,R : in Foobar) return Boolean;
> private
>    procedure Finalize (Object : in out Foobar);
> end foo;
> $ gnat -gnatwh -gnatc foo.ads
> gcc -c -gnatwh -gnatc foo.ads
> foo.ads:4:13: warning: declaration of "=" hides one in package
> Standard
> foo.ads:6:14: warning: declaration of "Finalize" hides one at line 3
> $

Well, I was going to suggest using the "overriding" keyword (not a bad
idea anyway), but when I tried it, GNAT still displayed the warnings.
Now *that* looks like a bug.  (I'm using 4.3.3; maybe it's been fixed
in a later version)

                              -- Adam



> The only way i see to solve this, is using pragma Warnings (Off); like
> this:
>
> $ cat bar.ads
> with Ada.Finalization;
> package bar is
>    type Barfoo is new Ada.Finalization.Controlled with null record;
> pragma Warnings(Off);
>    function "=" (L,R : in Barfoo) return Boolean;
> pragma Warnings(On);
> private
>    procedure Finalize (Object : in out Barfoo);
> end bar;
> $ gnatmake -gnatc -gnatwh bar.ads
> gcc -c -gnatwh -gnatc bar.ads
> bar.ads:8:14: warning: declaration of "Finalize" hides one at line 3
> $
>
> But that would either remove all warnings between both pragmas, or I
> would have to put them around every occurence of the hiding. I don't
> like turning all warnings off at once and I don't like adding two
> lines of source code just to prevent the warning. Still, I would like
> to remove them (without removing -gnatwh).
>
> Is there a proper way to do this?
>
> Greetings,
> Julian