Subject: Re: [PATCH] Makefile: add QUIET_GEN to "tags" and "TAGS" targets

From: Junio C Hamano <[email-masked]>
Date: Sat, 27 Mar 2021 22:56:28 -0700

Ævar Arnfjörð Bjarmason  <[email-masked]> writes:

> Don't show the very verbose $(FIND_SOURCE_FILES) command on every
> "make TAGS" invocation. Let's also use the "cmd >x+ && mv x+ x"
> pattern here so we don't momentarily clobber the file.

We do not "redirect" ctags and etags output into x+.  

	Let's use "generate into temporary and rename to the final
	after seeing the command that generated the output finished
	successfully" pattern.

Please also correct the explanation of why it is a good idea to use
the pattern in this case.  It is not about avoiding momentarily
clobbering the output.  It is to avoid leaving an incorrect output
generated by a failed command in the file with the filename that
consumers expect.

Thanks for making our Makefile a bit less noisy.  Anybody who makes
"clean" and its friends quiet will get a gold star ;-)

> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
> ---
>  Makefile | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 55c8035fa80..f317af1b602 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2690,12 +2690,15 @@ FIND_SOURCE_FILES = ( \
>  	)
>  
>  $(ETAGS_TARGET): FORCE
> -	$(RM) $(ETAGS_TARGET)
> -	$(FIND_SOURCE_FILES) | xargs etags -a -o $(ETAGS_TARGET)
> +	echo $(ALL_SOURCE_FILES)
> +	$(QUIET_GEN)$(RM) "$(ETAGS_TARGET)+" && \
> +	$(FIND_SOURCE_FILES) | xargs etags -a -o "$(ETAGS_TARGET)+" && \
> +	mv "$(ETAGS_TARGET)+" "$(ETAGS_TARGET)"
>  
>  tags: FORCE
> -	$(RM) tags
> -	$(FIND_SOURCE_FILES) | xargs ctags -a
> +	$(QUIET_GEN)$(RM) tags+ && \
> +	$(FIND_SOURCE_FILES) | xargs ctags -a -o tags+ && \
> +	mv tags+ tags
>  
>  cscope:
>  	$(RM) cscope*