Re: [PATCH] Makefile: check for cppcheck's --check-level option in cppcheck target

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Feb 27, 2024 at 05:29:47PM +0100, Stefano Brivio wrote:
> Don't run cppcheck to find out if the --check-level=exhaustive option
> is available, unless we're actually going to run cppcheck later.
> 
> To avoid this, move this check under the cppcheck target, and
> implement it in shell script instead of using Makefile directives,
> because we can't easily implement conditionals in recipes.
> 
> Reported-by: Rahil Bhimjiani <me@rahil.website>
> Link: https://bugs.gentoo.org/920795
> Fixes: 8640d62af719 ("cppcheck: Use "exhaustive" level checking when available")
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
> ---
>  Makefile | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index af4fa87..75d0bf3 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -287,17 +287,17 @@ clang-tidy: $(SRCS) $(HEADERS)
>  	-config='{CheckOptions: [{key: bugprone-suspicious-string-compare.WarnOnImplicitComparison, value: "false"}]}' \
>  	--warnings-as-errors=* $(SRCS) -- $(filter-out -pie,$(FLAGS) $(CFLAGS) $(CPPFLAGS)) -DCLANG_TIDY_58992
>  
> -CPPCHECK_EXHAUSTIVE :=
> -ifeq ($(shell cppcheck --check-level=exhaustive /dev/null > /dev/null 2>&1; echo $$?),0)
> -	CPPCHECK_EXHAUSTIVE += --check-level=exhaustive
> -endif
> -
>  SYSTEM_INCLUDES := /usr/include $(wildcard /usr/include/$(TARGET))
>  ifeq ($(shell $(CC) -v 2>&1 | grep -c "gcc version"),1)
>  VER := $(shell $(CC) -dumpversion)
>  SYSTEM_INCLUDES += /usr/lib/gcc/$(TARGET)/$(VER)/include
>  endif
>  cppcheck: $(SRCS) $(HEADERS)
> +	if cppcheck --check-level=exhaustive /dev/null > /dev/null 2>&1; then \
> +		CPPCHECK_EXHAUSTIVE="--check-level=exhaustive";		\
> +	else								\
> +		CPPCHECK_EXHAUSTIVE=;					\
> +	fi;								\
>  	cppcheck --std=c11 --error-exitcode=1 --enable=all --force	\
>  	--inconclusive --library=posix --quiet				\
>  	$(CPPCHECK_EXHAUSTIVE)						\

IIUC, this is essentially moving CPPCHECK_EXHAUSTIVE from a make
variable to a shell variable in the shell that make invokes.  Which is
fine, but I believe $(CPPCHECK_EXHAUSTIVE) will only expand to a make
variable.  To get the shell variable you'll need
$${CPPCHECK_EXHAUSTIVE}.  I suspect as written, this will always
expand empty.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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