Re: [RFC] add regenerate Makefile target

[Christophe Lyon <christophe.lyon@linaro.org>]

On Wed, 20 Mar 2024 at 16:34, Simon Marchi <simark@simark.ca> wrote:
>
> On 3/18/24 13:25, Christophe Lyon wrote:
> > Well the rule to regenerate Makefile.in (eg in in opcodes/) is a bit
> > more complex
> > than just calling automake. IIUC it calls automake --foreign it any of
> > *.m4 file from $(am__configure_deps) that is newer than Makefile.in
> > (with an early exit in the loop), does nothing if Makefile.am or
> > doc/local.mk are newer than Makefile.in, and then calls 'automake
> > --foreign Makefile'
>
> The rules looks complex because they've been generated by automake, this
> Makefile.in is not written by hand.  And I guess automake has put
> `--foreign` there because foreign is used in Makefile.am:
Yes, I know :-)

>
>   AUTOMAKE_OPTIONS = foreign no-dist
>
> But a simple call so `automake -f` (or `autoreconf -f`) just works, as
> automake picks up the foreign option from AUTOMAKE_OPTIONS, so a human
> or an external script who wants to regenerate things would probably just
> use that.

Indeed. I guess my concern is: if some change happens to
Makefile.am/Makefile.in which would imply that 'autoreconf -f' would
not work, how do we make sure autoregen.py (or whatever script) is
updated accordingly? Or maybe whatever change is made to
Makefile.am/Makefile.in, 'autoreconf -f' is supposed to handle it
without additional flag?

>
> > The bot I want to put in place would regenerate things as they are
> > supposed to be, then build and run the testsuite to make sure that
> > what is supposed to be committed would work (if the committer
> > regenerates everything correctly)
>
> For your job, would it be fine to just force-regenerate everything and
> ignore timestamps (just like the buildbot's autoregen job wants to do)?
> It would waste a few cycles, but it would be much simpler.
>
Yes, that would achieve the purpose: be able to handle as many patches
as possible in precommit-CI.
And as described earlier, for binutils this currently means:
autoregen
confgure --enable-maintainer-mode
make all (with a low -j value otherwise we have random build failures)
and my proposal to workaround the problem with -j is to do
make all-bfd all-libiberty regenerate -j1
make all -j XXX

Another possibility would be a policy change in how patches are
submitted, to require that they contain all the autogenerated files.


> Simon