Re: [PATCH v2 1/5] Documentation/Makefile: conditionally include doc.dep

[Junio C Hamano <gitster@pobox.com>]

Ramsay Jones <ramsay@ramsayjones.plus.com> writes:

> Notice that, since the 'doc.dep' file does not exist, make takes the
> time (about 8s) to generate several files in order to create the doc.dep
> include file. (If an 'include' file is missing, but a target for the
> said file is present in the Makefile, make will execute that target
> and, if that file now exists, throw away all its internal data and
> re-read and re-parse the Makefile). Having spent the time to include
> the 'doc.dep' file, the 'clean' target immediately deletes those files.
>
> In order to eliminate such wasted effort, use the value of the internal
> $(MAKECMDGOALS) variable to only '-include doc.dep' when the target is
> not 'clean'. (This drops the time down to 12.364s, on my laptop, giving
> an improvement of 47.02%).

Nicely explained.  It might be worth saying

    ... the clean target immediately deletes those files.  The rules
    and definitions of doc.dep however does not affect what 'clean'
    target removes otherwise, so we can do without all this.

The last paragraph made me wonder what should happen for 'distclean'
etc., but luckily there is only 'clean' in Documentation/Makefile ;-)

> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> ---
>  Documentation/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/Documentation/Makefile b/Documentation/Makefile
> index 80d1908a44..652d57a1b6 100644
> --- a/Documentation/Makefile
> +++ b/Documentation/Makefile
> @@ -286,7 +286,9 @@ doc.dep : $(docdep_prereqs) $(wildcard *.txt) $(wildcard config/*.txt) build-doc
>  	$(PERL_PATH) ./build-docdep.perl >$@+ $(QUIET_STDERR) && \
>  	mv $@+ $@
>  
> +ifneq ($(MAKECMDGOALS),clean)
>  -include doc.dep
> +endif
>  
>  cmds_txt = cmds-ancillaryinterrogators.txt \
>  	cmds-ancillarymanipulators.txt \