[Plucky/Unstable PATCH 2/2] UBUNTU: [Packaging] remove unneeded prerequisites of $(DEBIAN)/control.stub

[Masahiro Yamada]

On Wed, Nov 20, 2024 at 6:05 PM Agathe Porte <agathe.porte at canonical.com> wrote:
>
> 2024-11-20 03:22 CET, Masahiro Yamada:
> > $(DEBIAN)/control.stub is marked as .PHONY.
> >
> > There is no need to specify version-controlled files as prerequisites
> > for a phony target since they already exist.
> >
> > Signed-off-by: Masahiro Yamada <masahiro.yamada at canonical.com>
> > ---
> >
> >  debian/rules | 8 +-------
> >  1 file changed, 1 insertion(+), 7 deletions(-)
> >
> > diff --git a/debian/rules b/debian/rules
> > index 600e7bab2150..d1a6c2a78521 100755
> > --- a/debian/rules
> > +++ b/debian/rules
> > @@ -180,13 +180,7 @@ UBUNTU_COMPATIBLE_SIGNING=$(shell grep -qx ' *Subject: C = GB, ST = Isle of Man,
> >
> >  # Misc stuff
> >  .PHONY: $(DEBIAN)/control.stub
> > -$(DEBIAN)/control.stub:                              \
> > -             debian/scripts/control-create           \
> > -             $(control_files)                        \
> > -             debian/canonical-revoked-certs.pem      \
> > -             debian/control.d/flavour-module.stub    \
> > -             $(DEBIAN)/changelog                     \
> > -             $(wildcard $(DEBIAN)/control.d/*)
> > +$(DEBIAN)/control.stub: debian/canonical-revoked-certs.pem
> >       for i in $(control_files); do                                           \
> >         cat $$i;                                                              \
> >         echo "";                                                              \
>
> I think the prerequisites are still useful in the case one of them is
> deleted by accident for whatever reason: the rule will fail early saying
> that the required file is missing.
>
> It also allows to see what the rule depends on, even if it is PHONY and
> will run everytime.
>
> See the below example Makefile:
>
>         .PHONY: foo
>         foo: in.txt
>                 @echo Hello
>
> When run without in.txt:
>
>         make foo
>         make: *** No rule to make target 'in.txt', needed by 'foo'.  Stop.
>
> I think we should keep this dependency list to fail early.
>
> Maybe we could just drop the $(wildcard $(DEBIAN)/control.d/*) since
> it will always "be true" as a dependency and brings no real value.
>
> What do you think?


In general, I tend to drop check-in files from prerequisites
because if they were missing for some reason, the build
rule would fail for "No such file or directory" error anyway.

However, in this case, the build rule is overly long, and
multiple commands are piped together.

Here,

  for i in $(control_files); do cat $$i; echo ""; done |  ...

If any file in $(control_files) were deleted accidentally,
you would see some error message, but Make may continue
running and finish successfully because the error status
on the left ride of the pipe operator is ignored.

I am fine with keeping this code as-is for now.
(but, this part will be cleaned up more if my later patches are accepted)