Re: [PATCH v2] Makefile: avoid breaking compilation database generation with DEVELOPER

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Sep 23, 2021, 01:41 UTC
Message-ID: <YUvbU9HX6JA+MKd0@camp.crustytoothpaste.net>
In-Reply-To: <20210922185702.4328-1-carenas@gmail.com>

On 2021-09-22 at 18:57:02, Carlo Marcelo Arenas Belón wrote:

Show 32 quoted lines

> 3821c38068 (Makefile: add support for generating JSON compilation
> database, 2020-09-03), adds a feature to be used with clang to generate
> a compilation database by copying most of what was done before with the
> header dependency, but by doing so includes on its availability check
> the CFLAGS which became specially problematic once DEVELOPER=1 implied
> -pedantic as pointed out by Ævar[1].
> 
> Remove the unnecessary flags in the availability test, so it will work
> regardless of which other warnings are enabled or if the compiler has
> been told to error on them.
> 
> [1] https://lore.kernel.org/git/patch-1.1-6b2e9af5e67-20210922T103749Z-avarab@gmail.com/
> 
> Helped-by: Eric Sunshine <sunshine@sunshineco.com>
> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
> ---
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index 9df565f27b..d5c6d0ea3b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1302,7 +1302,7 @@ GENERATE_COMPILATION_DATABASE = no
>  endif
>  
>  ifeq ($(GENERATE_COMPILATION_DATABASE),yes)
> -compdb_check = $(shell $(CC) $(ALL_CFLAGS) \
> +compdb_check = $(shell $(CC) \
>  	-c -MJ /dev/null \
>  	-x c /dev/null -o /dev/null 2>&1; \
>  	echo $$?)

Are you sure this results in a functional set of files? As I understand it, the reason that clangd needs these files is because it needs to know what include arguments and headers are supposed to be used, since C programs don't have a standard layout. In this case, it looks like you're removing all of the -I arguments, so in that case clangd wouldn't be able to find all the files it's supposed to.

Of course, if I've misunderstood, and somehow we get those arguments elsewhere, that's fine, but I just want to be sure we don't regress the behavior.

-- 
brian m. carlson (he/him or they/them)
Toronto, Ontario, CA