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From: mockturtle <framefritti@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Simple Warnings Needs
Date: Wed, 23 Feb 2011 11:56:36 -0800 (PST)
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Date: 2011-02-23T11:56:36-08:00
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On Wednesday, February 23, 2011 7:52:37 PM UTC+1, Rego wrote:
> I would like to know (in more details than gnat documentation) the critic=
ality of these warnings options:=20
>  ** "-gnatwd" (Implicit dereferencing)
>  ** "-gnatwf" (Unreferenced formals)
>  ** "-gnatwh" (Hiding)
>  ** "-gnatwm" (Modified but unreferenced variables)
>  ** "-gnatwk" (Variables that could be constants)
>=20

Hmmm... I would say that at least some of these warnings do not induce secu=
rity threats.  For example, Hiding warning should be raised in a context si=
milar to this (disclaimer: I do not have an Ada compiler at hand [my dog ea=
t it :-)], so I cannot test the code)

  with A;  -- it declares Foo : Integer;
 =20
  procedure Warn is
    use A;  -- make A.Foo visible
    Foo : integer; -- Warning: Hiding A.Foo
    Goo : integer;
  begin
     -- The local one or the one in A?
     Goo :=3D Foo; =20
  end Warn;

In this case, I would say, the compiler warns you since you could want to a=
ccess the Foo in A and you did not notice that you hide it.  I would say th=
at in a typical case this does not give rise to a security threat, but to a=
 non-working program.

About "-gnatwf" (Unreferenced formals), "-gnatwm" (Modified but unreference=
d variables)  I think that the idea is to warn about "strange" construct: w=
hy did you modify that variable if you are not reading it again?  This is s=
trange and maybe it is the consequence of an error.  Again, the risk is hav=
ing a program with a bug rather than a security threat.=20

I do not know about the remaining two.  Maybe "-gnatwk" (Variables that cou=
ld be constants) it is just about optimization and/or declaring explicitly =
that the variable will not change, but I am not sure.