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Date: Wed, 20 Mar 2024 00:35:25 +0000
From: Justin Stitt <justinstitt@google.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: rostedt@goodmis.org, mhiramat@kernel.org, 
	mathieu.desnoyers@efficios.com, ndesaulniers@google.com, morbo@google.com, 
	linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, llvm@lists.linux.dev, 
	patches@lists.linux.dev
Subject: Re: [PATCH 1/2] compiler_types: Ensure __diag_clang() is always
 available
Message-ID: <qn6cklc5fvjg4cnvavyncj73qmc6k5eyzrmpqsrkpaihi35per@3k2sodhtlcnt>
References: <20240319-tracing-fully-silence-wstring-compare-v1-0-81adb44403f5@kernel.org>
 <20240319-tracing-fully-silence-wstring-compare-v1-1-81adb44403f5@kernel.org>
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In-Reply-To: <20240319-tracing-fully-silence-wstring-compare-v1-1-81adb44403f5@kernel.org>

Hi,

On Tue, Mar 19, 2024 at 09:07:52AM -0700, Nathan Chancellor wrote:
> Attempting to use __diag_clang() and build with GCC results in a build
> error:
> 
>   include/linux/compiler_types.h:468:38: error: 'ignore' undeclared (first use in this function); did you mean 'inode'?
>     468 |         __diag_ ## compiler(version, ignore, option)
>         |                                      ^~~~~~
> 
> This error occurs because __diag_clang() is only defined in
> compiler-clang.h, which is only included when using clang as the
> compiler. This error has not been seen before because __diag_clang() has
> only been used in __diag_ignore_all(), which is defined in both
> compiler-clang.h and compiler-gcc.h.
> 
> Add an empty stub for __diag_clang() in compiler_types.h, so that it is
> always defined and just becomes a no-op when using GCC.
> 
> Fixes: f014a00bbeb0 ("compiler-clang.h: Add __diag infrastructure for clang")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Justin Stitt <justinstitt@google.com>

> ---
>  include/linux/compiler_types.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index 3e64ec0f7ac8..fb0c3ff5497d 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -461,6 +461,10 @@ struct ftrace_likely_data {
>  #define __diag_GCC(version, severity, string)
>  #endif
>  
> +#ifndef __diag_clang
> +#define __diag_clang(version, severity, string)
> +#endif
> +
>  #define __diag_push()	__diag(push)
>  #define __diag_pop()	__diag(pop)
>  
> 
> -- 
> 2.44.0

Thanks
Justin