From: D. Ben Knoble <ben.knoble+github@gmail.com>
Date: Wed, 11 Feb 2026 20:15:00 GMT
Subject: Re: [PATCH] meson: regenerate config-list.h when Documentation changes
Message-ID: <CALnO6CCoSKKxFZVPbWpTdxkW0xfxwZgJNv1wS2Qz7GGhAKkeAQ@mail.gmail.com>
In-Reply-To: <171c0724-7891-41d7-8a70-94fbbf8b43b2@gmail.com>

On Wed, Feb 11, 2026 at 9:05 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
>
> On 11/02/2026 10:58, Patrick Steinhardt wrote:
> > On Wed, Feb 11, 2026 at 09:44:48AM +0000, Phillip Wood wrote:
> >> On 11/02/2026 07:42, Patrick Steinhardt wrote:
> >>> On Mon, Feb 09, 2026 at 04:50:06PM -0500, D. Ben Knoble wrote:
> >>>>> On Sat, Feb 07, 2026 at 04:59:17PM -0500, D. Ben Knoble wrote:
> >>> [snip]
> >>>> Only, things are behaving oddly. For example:
> >>>>
> >>>>       λ meson setup build2
> >>>>       λ ninja -C build2
> >>>>
> >>>> works fine, but
> >>>>
> >>>>       λ ls -l build2/config*
> >>>>       -rw-r--r-- 1 benknoble benknoble 17169  9 févr. 16:39 build2/config-list.h
> >>>>
> >>>> I don't see the dependency file.
> >>>
> >>>> Further, re-building seems to get stuck (I get
> >>>> similar symptoms if I add or remove a relevant config.adoc file, but let's keep
> >>>> it simple for now):
> >>>>
> >>>>       λ ninja -C build2
> >>>>       ninja: Entering directory `build2'
> >>>>       [1/28] Generating GIT-VERSION-FILE with a custom command (wrapped by meson to set env)
> >>>
> >>> With "stuck" you mean that it doesn't do anything, or that it doesn't
> >>> actually rebuild?
> >>>
> >>> I guess it kind of makes sense that a new file wouldn't trigger a
> >>> rebuild, even though I would have expected a removed one to trigger one.
> >>> After all, the dependency file only tracks the set of _existing_ files
> >>> so that we know when to rebuild, and of course the dependency file only
> >>> gets regenerated in case any of those files changes.
> >>
> >> If anyone adds a new file under Documentation/config/ they will need to
> >> update Documentation/config.adoc which should then trigger the rebuild. That
> >> rebuld will then add the new file to the list of dependencies. If they
> >> remove a file we should pick that up with the dependencies that are already
> >> listed.
> >
> > Oh? Well, if that's the case then the additional changes should indeed
> > not be required.
>
> I think so. The only problem I can think of is that if you delete a
> file, build, restore the file without changing anything else and build
> again then config-list.h will not be rebuilt because the deleted file
> would have been removed from the list of dependencies by the previous build.
>
> >>
> >> It would be really nice if we can avoid regenerating the depfile with every
> >> build.
> >
> > Agreed. So maybe the first patch I sent is sufficient after all?
>
> We need to add the script to the list of dependencies and reading the
> comments in
> https://github.com/ninja-build/ninja/blob/master/src/depfile_parser.in.cc
> we should be backslash escaping space, hash and backslash in the
> filename when we write the dependencies. Apart from that I think it is ok.

Re-reading, I now see something actionable:
- use Patrick's original patch
- add the script itself to dependencies
- quote dependencies correctly

Thanks

> I guess the alternative is to bite the bullet and list these
> dependencies explicitly as we do for other targets.
>
> Thanks
>
> Phillip
>