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Date:   Wed, 5 Jul 2023 09:20:26 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Borislav Petkov <bp@alien8.de>
Cc:     linux-kbuild@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kbuild: Enable -Wenum-conversion by default
Message-ID: <20230705162026.GA2951@dev-arch.thelio-3990X>
References: <20230704221951.7396-1-bp@alien8.de>
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On Wed, Jul 05, 2023 at 12:19:51AM +0200, Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
> 
> This diagnostic checks whether there is a type mismatch when
> converting enums (assign an enum of type A to an enum of type B, for
> example) and it caught a legit issue recently. The reason it didn't show
> is because that warning is enabled only with -Wextra with GCC. Clang,
> however, enables it by default.
> 
> GCC folks were considering enabling it by default but it was too noisy
> back then:
> 
>   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78736
> 
> Now that due to clang all those warnings have been fixed, enable it with
> GCC too.
> 
> allmodconfig tests done with: x86, arm{,64}, powerpc{,64}, riscv
> crossbuilds.
> 
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>

Yes please :)

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  Makefile | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Makefile b/Makefile
> index 7a5a175f708f..428132b3d6dd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1082,6 +1082,9 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
>  # Require designated initializers for all marked structures
>  KBUILD_CFLAGS   += $(call cc-option,-Werror=designated-init)
>  
> +# Warn if there is an enum types mismatch
> +KBUILD_CFLAGS	+= $(call cc-option,-Wenum-conversion)
> +
>  # change __FILE__ to the relative path from the srctree
>  KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
>  
> -- 
> 2.41.0
>