Re: CVS commit: src/distrib/sets/lists/debug

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Sat, 27 Jun 2026 21:51:54 +0700
> From: Robert Elz <kre%munnari.OZ.AU@localhost>
> 
>     Date:        Fri, 26 Jun 2026 22:47:42 +0000
>     From:        "Taylor R Campbell" <riastradh%netbsd.org@localhost>
>     Message-ID:  <20260626224742.DE8F7FA2B%cvs.NetBSD.org@localhost>
> 
>   | debug/shl.mi: Cull obsolete linkable shlibs and explain why.
>   |
>   | This is not a _good_ system but it's the system we have:
> 
> Surely we don't need that for the *debug* libs - this:
> 
> +#       This way,
> +#       systems that still have the old shared libraries after an
> +#       update, which applications might have been linked against,
> 
> isn't going to apply usually to anything linked against debug libs,
> and if someone has such an application, they'd be much better to
> relink it against the newer debug lib that has been installed, and
> perhaps no longer need to debug if whatever issue caused the need
> for that might have been fixed in the update.

If someone is still running applications against an older version of a
library, they should be able to debug them too.

Relinking is generally not enough: the application generally has to be
recompiled too -- if you just relink, you might be using code built
against old function prototypes allocating old struct sizes with a
library that defines new function prototypes and using new struct
sizes, to everyone's chagrin.

You could make the same argument that an older application shouldn't
be _run_ against the old library and everyone should just rebuild all
their old applications, but that would be a dramatic departure from
NetBSD's long-standing approach to compatibility.

> obsoleting old debug libs (though not always done) has been the
> practice for a long time now,

It has been inconsistent: if you review the history of debug/shl.mi,
you'll find some cases of deletion, some cases of obsoletion, and some
cases of fixing previous commit by deleting a wrong obsoletion.  It
was always wrong to obsolete for the same reasons as listed in
base/shl.mi.  We just never had a comment at the top of debug/shl.mi
to remind people to delete, rather than obsolete -- which is why I
just added one.

> without any complaints about problems I have ever seen.

I'm complaining here because this has bitten me in the past.