[PATCH] doc: Fix parallel build of roff files

[Austin Clements]

On Sat, 10 May 2014, "W. Trevor King" <wking at tremily.us> wrote:
> On Thu, Apr 17, 2014 at 04:34:57PM -0400, Austin Clements wrote:
>> +$(DOCBUILDDIR)/.roff.stamp: ${MAN_RST_FILES}
>>  ifeq ($(HAVE_SPHINX),1)
>>  	$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(DOCBUILDDIR)/man
>>  	for section in 1 5 7; do \
>> @@ -48,6 +54,7 @@ else
>>  	@echo "Fatal: build dependency fail."
>>  	@false
>>  endif
>> +	touch ${MAN_ROFF_FILES} $@
>
> I'm poking around in the Makefile, and don't understand why we're
> touching ${MAN_ROFF_FILES} here.  Either they were just created by
> Sphinx/rst2man, or we died with the @false.  I doubt Sphinx or
> prerst2man.py are intelligent enough to not clobber the roff files if
> their content hasn't changed, but I don't see a point in explicitly
> bumping timestamps either.
>
> I think I'll drop the ${MAN_ROFF_FILES} as part of the patch I'm
> working on, but let me know if I'm just missing something.

I think you're right.  I can't reconstruct why I touched
${MAN_ROFF_FILES} here.  Touching $@ obviously matters, but I think it
should be safe to drop the ${MAN_ROFF_FILES}.

> Cheers,
> Trevor