Re: Simple Warnings Needs

[mockturtle <framefritti@gmail.com>]

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 criticality of these warnings options: 
>  ** "-gnatwd" (Implicit dereferencing)
>  ** "-gnatwf" (Unreferenced formals)
>  ** "-gnatwh" (Hiding)
>  ** "-gnatwm" (Modified but unreferenced variables)
>  ** "-gnatwk" (Variables that could be constants)
> 

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

  with A;  -- it declares Foo : Integer;
  
  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 := Foo;  
  end Warn;

In this case, I would say, the compiler warns you since you could want to access the Foo in A and you did not notice that you hide it.  I would say that 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 unreferenced variables)  I think that the idea is to warn about "strange" construct: why did you modify that variable if you are not reading it again?  This is strange and maybe it is the consequence of an error.  Again, the risk is having a program with a bug rather than a security threat. 

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