Re: GCC plugins packaging (for AFL++)

On Tue, Jul 21, 2026 at 12:00:22PM +0200, Florian Weimer wrote:
> * Richard W. M. Jones:
> 
> > On Thu, Jun 25, 2026 at 06:21:01PM +0200, Florian Weimer wrote:
> >> * Richard W. M. Jones:
> >> 
> >> > Apparently GCC plugins depend on the exact GCC major.minor.release
> >> > version (rather than, say, just the major version as with Clang).  Or
> >> > AFL *thinks* it needs to depend on the exact version, although you
> >> > could set an environment variable to skip the check, see:
> >> >
> >> >   https://github.com/AFLplusplus/AFLplusplus/blob/edaf3ad04d64185cae856c75ca4676cbb14a35b5/instrumentation/afl-gcc-pass.so.cc#L621
> >> >
> >> > Do GCC plugins really depend on the exact major.minor.release of GCC?
> >> 
> >> They do.  We rebuild the annobin plugin each time we update GCC, and
> >> reconfigure to use that annobin version if the separately built annobin
> >> plugin was built by a different GCC version (and not the currently
> >> installed one).
> >
> > Sorry for the late reply here.
> >
> > I don't have any good ideas here, except that I want to avoid having
> > to rebuild AFL every time we rebuild GCC.  That's not going to make
> > anyone happy.
> >
> > Is there a stable subset of APIs or is there just no hope?
> 
> Thinks like the GCC options array are unstable, so there's really no
> good way to avoid recompilation.
> 
> How often do you expect to update AFL?

There's usually a new release every month or two.

> We could build the plugin during the GCC build itself, perhaps.

Unfortunately AFL uses a completely insane hand-rolled build system,
so I'm not confident that I could cleanly separate out the plugin from
the rest, or that the build system wouldn't change randomly in future
breaking everything.

I think it's probably best to leave it for now and see if any Fedora
users complain.  AFL has several other instrumentation methods so it
doesn't depend on the plugin.

Rich.

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