From: D. Ben Knoble <ben.knoble@gmail.com>
Date: Tue, 24 Feb 2026 14:12:57 GMT
Subject: Re: [PATCH v6] build: regenerate config-list.h when Documentation changes
Message-ID: <CALnO6CBsj_2+pZG+bqbrE3tQH=6_kqdtCnNPm8MfJ2XZOA9e3Q@mail.gmail.com>
In-Reply-To: <39acbf7e-86f4-4dbe-8b58-3c04fccd7984@gmail.com>

On Tue, Feb 24, 2026 at 6:00 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
>
>
>
> On 24/02/2026 09:58, Patrick Steinhardt wrote:
> > On Mon, Feb 23, 2026 at 04:41:48PM -0500, Ben Knoble wrote:
> >>> Le 23 févr. 2026 à 01:55, SZEDER Gábor <szeder.dev@gmail.com> a écrit :
> >>> On Sat, Feb 21, 2026 at 09:07:17AM -0500, D. Ben Knoble wrote:
> >>>> diff --git a/Makefile b/Makefile
> >>>> index 7f37ad8f58..6f926ffb1f 100644
> >>>> --- a/Makefile
> >>>> +++ b/Makefile
> >>>> @@ -2688,9 +2688,10 @@ $(BUILT_INS): git$X
> >>>>     cp $< $@
> >>>>
> >>>> config-list.h: generate-configlist.sh
> >>>> +    @mkdir -p .depend
> >>>> +    $(QUIET_GEN)$(SHELL_PATH) ./generate-configlist.sh . $@ .depend/config-list.h.d
> >>>>
> >>>> -config-list.h: Documentation/*config.adoc Documentation/config/*.adoc
> >>>> -    $(QUIET_GEN)$(SHELL_PATH) ./generate-configlist.sh . $@
> >>>> +-include .depend/config-list.h.d
> >>>
> >>> This breaks the build when something disappears from
> >>> Documentation/config/:
> >>>
> >>>   $ git checkout origin/seen
> >>>   HEAD is now at 57edfa3ce8 Merge branch 'ty/setup-error-tightening' into seen
> >>>   $ ls -l Documentation/config/hook.adoc
> >>>   -rw-rw-r-- 1 szeder szeder 3828 Feb 23 07:50 Documentation/config/hook.adoc
> >>>   $ git grep hook.adoc
> >>>   Documentation/git-hook.adoc:include::config/hook.adoc[]
> >>>   Documentation/howto/meson.build:  'rebuild-from-update-hook.adoc',
> >>>   Documentation/meson.build:  'git-hook.adoc' : 1,
> >>>   $ make V=1 config-list.h
> >>>   /bin/sh ./generate-configlist.sh . config-list.h .depend/config-list.h.d
> >>>   $ git checkout 0aabf70f60
> >>>   Previous HEAD position was 57edfa3ce8 Merge branch 'ty/setup-error-tightening' into seen
> >>>   HEAD is now at 0aabf70f60 build: regenerate config-list.h when Documentation changes
> >>>   $ ls -l Documentation/config/hook.adoc
> >>>   ls: cannot access 'Documentation/config/hook.adoc': No such file or directory
> >>>   $ git grep hook.adoc
> >>>   Documentation/howto/meson.build:  'rebuild-from-update-hook.adoc',
> >>>   Documentation/meson.build:  'git-hook.adoc' : 1,
> >>>   $ make V=1 config-list.h
> >>>   GIT_VERSION=2.53.0.119.g0aabf70f60
> >>>   make: *** No rule to make target 'Documentation/config/hook.adoc', needed by 'config-list.h'.  Stop.
> >>>   $ grep hook.adoc .depend/config-list.h.d
> >>>   config-list.h: ./Documentation/config/hook.adoc
> >>
> >> Indeed. This might arise while bisecting, which was my original
> >> motivation. Thoughts on a path forward? At least this issue (to me) is
> >> clearer than a spurious test failure :)
> >
> > For Meson this case works alright. So maybe we just drop the changes to
> > the Makefile and call it a day?
> >
> > An alternative would be to have the following patch on top:
> >
> > diff --git a/generate-configlist.sh b/generate-configlist.sh
> > index 39ac8845ab..e28054f9e0 100755
> > --- a/generate-configlist.sh
> > +++ b/generate-configlist.sh
> > @@ -41,7 +41,12 @@ EOF
> >   if test -n "$DEPFILE"
> >   then
> >       QUOTED_OUTPUT="$(printf '%s\n' "$OUTPUT" | sed 's,[&/\],\\&,g')"
> > -     printf '%s\n' "$SOURCE_DIR"/Documentation/*config.adoc \
> > -             "$SOURCE_DIR"/Documentation/config/*.adoc |
> > -             sed -e 's/[# ]/\\&/g' -e "s/^/$QUOTED_OUTPUT: /" >"$DEPFILE"
> > +     {
> > +             printf '%s\n' "$SOURCE_DIR"/Documentation/*config.adoc \
> > +                     "$SOURCE_DIR"/Documentation/config/*.adoc |
> > +                     sed -e 's/[# ]/\\&/g' -e "s/^/$QUOTED_OUTPUT: /"
> > +             printf '%s:\n' "$SOURCE_DIR"/Documentation/*config.adoc \
> > +                     "$SOURCE_DIR"/Documentation/config/*.adoc |
> > +                     sed -e 's/[# ]/\\&/g'
> > +     } >"$DEPFILE"
> >   fi
> >
> > What it does is to also create an empty target for all of the
> > dependencies. Which is in fact what GCC/Clang also do when you pass -MP:
>
> Oh, I was wondering how they got around the problem we're seeing here.
> While it seems ninja is happy it ignore missing dependencies in
> depfiles, are we sure the build systems meson uses on other platforms
> are as well? If not it might be worth adding this, rather than just
> dropping the Makefile changes.
>
> Thanks
>
> Phillip
>
> >
> >      $ cat main.c
> >      #include "foo.h"
> >      int main()
> >      {
> >          puts("foobar");
> >          return 0;
> >      }
> >
> >      $ clang -MMD -MP main.c
> >      $ cat main.d
> >      main.o: main.c foo.h
> >      foo.h:
> >
> > Patrick

Yep, I agree with Phillip: I have a feeling Meson intends folks to
produce output like GCC/Clang do, so let's honor that (even if it's
not well-documented IMO). Will add.

-- 
D. Ben Knoble