Re: RFS: dbusada

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Reto Buerki wrote:
> On 03/07/2012 10:50 AM, Ludovic Brenta wrote:
> > Reto Buerki wrote:
> > > > * Build-Depend on gnat in addition to gnat-4.6
> > > I don't exactly understand the rationale for this rule. In contrast 
> > > to
> > > other packages the gnatgcc command is not needed to build dbusada. 
> > > And I
> > > explicitly Build-Depend on the upcoming default compiler gnat-4.6 
> > > so ABI
> > > compatibility to other Ada packages is guaranteed.
> >
> > In section 4:
> >
> > "Rule: Package ‘gnat’ is the default Ada compiler for Debian. All 
> > packages
> > containing Ada programs or libraries SHALL use this compiler."
> >
> > This rule makes it explicit that the package 'gnat-4.6' is NOT the 
> > default
> > Ada compiler; the package 'gnat' is.
>
> And the package description of 'gnat' is:
> "This is an empty package that depends on the default Ada compiler 
> for
>  Debian, which is part of the GNU Compiler Collection."
>
> gnat currently depends on gnat-4.6, making it the 'current' default 
> Ada
> compiler.
>
> I see no real (besides policy compliance) benefit here for depending 
> on
> gnat in addition to gnat-4.6. The dbusada package defines that it 
> needs
> exactly gnat-4.6 to build and that every package that depends on 
> dbusada
> MUST also use this compiler.

This is not sufficient. The policy is designed so that all Ada packages 
use
the *same* compiler.  We want to prevent a situation where maintainer A
uploads package libfoo1-dev (depending on gnat-4.6) and maintainer B 
uploads
package libbar2-dev (depending on gnat-4.7).  This is not an error as 
far as
the compiler is concerned but it is a policy violation because we want 
end
users to be able to link their executables against *all* libraries if 
they
so wish.  Worse, nothing tells maintainer B about this violation.

Now suppose maintainer B adds Build-Depends: gnat to libbar; the policy
violation immediately becomes apparent; the package FTBFS because it 
does not
use the default compiler.

In your case, you happen to be using the current default compiler "by
accident"; the policy requires you to use the default compiler 
explicitly and
"by design".

--
Ludovic Brenta.