Re: [PATCH v2 4/5] Makefile: don't use "FORCE" for tags targets

[Ramsay Jones <ramsay@ramsayjones.plus.com>]

On 29/06/2021 12:12, Ævar Arnfjörð Bjarmason wrote:
> Remove the "FORCE" dependency from the "tags", "TAGS" and "cscope.out"
> targets, instead make them depend on whether or not the relevant
> source files have changed.
> 
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  Makefile | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 2e3b257164..7b0d9773b0 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2727,19 +2727,21 @@ FIND_SOURCE_FILES = ( \
>  		| sed -e 's|^\./||' \
>  	)
>  
> -$(ETAGS_TARGET): FORCE
> +FOUND_SOURCE_FILES = $(shell $(FIND_SOURCE_FILES))
> +
> +$(ETAGS_TARGET): $(FOUND_SOURCE_FILES)
>  	$(QUIET_GEN)$(RM) "$(ETAGS_TARGET)+" && \
>  	$(FIND_SOURCE_FILES) | xargs etags -a -o "$(ETAGS_TARGET)+" && \
>  	mv "$(ETAGS_TARGET)+" "$(ETAGS_TARGET)"
>  
> -tags: FORCE
> +tags: $(FOUND_SOURCE_FILES)
>  	$(QUIET_GEN)$(RM) tags+ && \
>  	$(FIND_SOURCE_FILES) | xargs ctags -a -o tags+ && \
>  	mv tags+ tags

I was expecting to see the above targets to be changed, similarly to ...

>  
> -cscope.out:
> +cscope.out: $(FOUND_SOURCE_FILES)
>  	$(QUIET_GEN)$(RM) cscope.out && \
> -	$(FIND_SOURCE_FILES) | xargs cscope -f$@ -b
> +	echo $(FOUND_SOURCE_FILES) | xargs cscope -f$@ -b

... this hunk (ie. 'an "echo <list> | xargs" pattern')
Indeed, the above phrase was taken from the commit message of
the next patch (5/5), which implies that this change had already
happened (presumably in this patch).

ATB,
Ramsay Jones

>  
>  .PHONY: cscope
>  cscope: cscope.out
> @@ -2923,7 +2925,7 @@ check: config-list.h command-list.h
>  		exit 1; \
>  	fi
>  
> -FOUND_C_SOURCES = $(filter %.c,$(shell $(FIND_SOURCE_FILES)))
> +FOUND_C_SOURCES = $(filter %.c,$(FOUND_SOURCE_FILES))
>  COCCI_SOURCES = $(filter-out $(THIRD_PARTY_SOURCES),$(FOUND_C_SOURCES))
>  
>  %.cocci.patch: %.cocci $(COCCI_SOURCES)
>