Re: [PATCH] Makefile: add and use the ".DELETE_ON_ERROR" flag

From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Felipe Contreras <felipe.contreras@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Jeff King <peff@peff.net>
Subject: Re: [PATCH] Makefile: add and use the ".DELETE_ON_ERROR" flag
Date: Tue, 29 Jun 2021 10:17:43 +0200	[thread overview]
Message-ID: <8735t1gk0d.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <60d39ef9a8071_429020896@natae.notmuch>

On Wed, Jun 23 2021, Felipe Contreras wrote:

> Ævar Arnfjörð Bjarmason wrote:
>> 
>> On Wed, Jun 23 2021, Felipe Contreras wrote:
>> 
>> > Ævar Arnfjörð Bjarmason wrote:
>> >> @@ -2243,7 +2253,6 @@ SCRIPT_DEFINES = $(SHELL_PATH_SQ):$(DIFF_SQ):$(GIT_VERSION):\
>> >>  	$(gitwebdir_SQ):$(PERL_PATH_SQ):$(SANE_TEXT_GREP):$(PAGER_ENV):\
>> >>  	$(perllibdir_SQ)
>> >>  define cmd_munge_script
>> >> -$(RM) $@ $@+ && \
>> >>  sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
>> >>      -e 's|@SHELL_PATH@|$(SHELL_PATH_SQ)|' \
>> >>      -e 's|@@DIFF@@|$(DIFF_SQ)|' \
>> >
>> > Any reason why the same isn't done for the $(BUILT_INS) target?
>> >
>> >> @@ -2514,7 +2522,6 @@ endif
>> >>  ifeq ($(GENERATE_COMPILATION_DATABASE),yes)
>> >>  all:: compile_commands.json
>> >>  compile_commands.json:
>> >> -	@$(RM) $@
>> >>  	$(QUIET_GEN)sed -e '1s/^/[/' -e '$$s/,$$/]/' $(compdb_dir)/*.o.json > $@+
>> >>  	@if test -s $@+; then mv $@+ $@; else $(RM) $@+; fi
>> >>  endif
>> >
>> > What about these?
>> >
>> >   $(REMOTE_CURL_ALIASES):
>> 
>> Uses a chain of ln/ln -s/cp, would need to add "-f" flags.
>
> Why? Isn't "x && a || b || c" the same as "a || b || c" if x is always true?

It does:

    rm x &&
    ln y x || ln -s y x || cp y x

If you run that you'll get a hardlink the first time around, but the
second time around you'll fall back to the "cp" if you remove the "rm".

>> >   $(LIB_FILE):
>> 
>> Can we rely on $(AR) happily clobbering things everywhere? Not knowing
>> is why I skipped it.
>
> We have c (create) in ARFLAGS, so presumably yes.

Will change.

>> >   $(ETAGS_TARGET):
>> >   tags:
>> >   cscope:
>> 
>> Addressed in the related:
>> https://lore.kernel.org/git/YNH+zsXDnRsT3uvZ@nand.local/T/#t
>
> I think ideally this patch should remove the $(RM) and the other patch
> should focus on the rest of the changes, but given the difficulty of
> landing chained patch series in git I understand the decision to clump
> them together.
>
> Cheers.