Re: Can't build previous versions of Emacs?

[Eli Zaretskii]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Fri, 15 Jul 2022 07:50:20 -0700
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
>  Lars Ingebrigtsen <larsi@gnus.org>, 
>  Ulrich Mueller <ulm@gentoo.org>, Eric Abrahamsen <eric@ericabrahamsen.net>,
>  emacs-devel@gnu.org
> 
> andrés ramírez <rrandresf@hotmail.com> writes:
> 
> > JIC. If You want to try emacs-20 right now. You try in on netbsd. netbsd
> > guys still compile and have a packaged emacs-20.
> >
> > If You want to try emacs-23. Ulrich and the gentoo guys have a heavily
> > patched emacs-23 version still compiling on latest gentoo. And they also
> > have an emacs18 still compiling too.
> 
> How about installing such patches on the release branches, so that it is
> easy to build them on recent machines?
> 
> It might even indirectly help with bisecting really old bugs by giving
> an idea of which patches might be needed to get various versions to
> build.

AFAIU only if you install on a single branch emacs-NN, and then merge
from it to emacs-NN+1, from there to emacs-NN+2, etc.  Which AFAICT
not what was actually done.