From: Harald Nordgren <haraldnordgren@gmail.com>
Date: Thu, 04 Jun 2026 07:06:49 GMT
Subject: Re: [PATCH] Makefile: drop duplicate %.a from link recipes
Message-ID: <CAHwyqnV6uh_yyO9FcUiXKfKPt15ojR3GOmRC06pW55f=KRu=Zw@mail.gmail.com>
In-Reply-To: <xmqqik7zqh4p.fsf@gitster.g>

On Thu, Jun 4, 2026 at 2:33 AM Junio C Hamano <gitster@pobox.com> wrote:
>
> "Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
> >  t/helper/test-%$X: t/helper/test-%.o GIT-LDFLAGS $(GITLIBS)
> > -     $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(filter %.a,$^) $(LIBS)
> > +     $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)
>
> I think the reason why the pattern to use only the .o files among
> the prerequisites and then use only the .a files among the same
> prerequisites (both filters $^) is used here is to make sure that the
> linker sees object files first before library archives, so that by
> the time its left-to-right scan sees the first library archive, all
> the missing symbols in the object files are known.  The above change
> depends on LIBS being a strict superset of all the library archive
> files ($GITLIBS in the current code, but that can be updated in the
> future) listed as prerequisites for the rule, but there is nothing to
> guarantee that, so it looks brittle.
>
> Exact same comment applies to the other two rules touched by this patch.

Hmm, there are other constructs like this that rely on $(LIBS) being a
superset of the archives, so the three rules changed here align with
the trend rather than introduce a new trend.

Not saying we shouldn't find a way to handle the overall brittleness.


Harald