[PATCH bpf-next v2 5/8] compiler-clang.h: Add __diag infrastructure for clang

[PATCH bpf-next v2 5/8] compiler-clang.h: Add __diag infrastructure for clang

[Kumar Kartikeya Dwivedi]

From: Nathan Chancellor <nathan@kernel.org>

Add __diag macros similar to those in compiler-gcc.h, so that warnings
that need to be adjusted for specific cases but not globally can be
ignored for LLVM compilation mode as well.

Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: llvm@lists.linux.dev
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 include/linux/compiler-clang.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index 3c4de9b6c6e3..f1aa41d520bd 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -68,3 +68,25 @@
 
 #define __nocfi		__attribute__((__no_sanitize__("cfi")))
 #define __cficanonical	__attribute__((__cfi_canonical_jump_table__))
+
+/*
+ * Turn individual warnings and errors on and off locally, depending
+ * on version.
+ */
+#define __diag_clang(version, severity, s) \
+	__diag_clang_ ## version(__diag_clang_ ## severity s)
+
+/* Severity used in pragma directives */
+#define __diag_clang_ignore	ignored
+#define __diag_clang_warn	warning
+#define __diag_clang_error	error
+
+#define __diag_str1(s)		#s
+#define __diag_str(s)		__diag_str1(s)
+#define __diag(s)		_Pragma(__diag_str(clang diagnostic s))
+
+#if CONFIG_CLANG_VERSION >= 110000
+#define __diag_clang_11(s)	__diag(s)
+#else
+#define __diag_clang_11(s)
+#endif
-- 
2.35.1

Re: [PATCH bpf-next v2 5/8] compiler-clang.h: Add __diag infrastructure for clang

[Nathan Chancellor]

Hi Kumar,

Thanks for sending this along!

On Thu, Mar 03, 2022 at 10:20:26AM +0530, Kumar Kartikeya Dwivedi wrote:
> From: Nathan Chancellor <nathan@kernel.org>
> 
> Add __diag macros similar to those in compiler-gcc.h, so that warnings
> that need to be adjusted for specific cases but not globally can be
> ignored for LLVM compilation mode as well.

I would word this last sentence as:

"ignored when building with clang."

Technically speaking, LLVM is not the one emitting the warnings, clang
is :) this is useful with LLVM=1 or CC=clang.

> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: llvm@lists.linux.dev
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

You should add your signed-off-by here to notate that you have touched
the patch per Documentation/process/submitting-patches.rst. It is also
courteous to note that you wrote the commit message, something along the
lines of:

"[Kumar: Wrote commit message]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>"

Regardless, this looks good to me with the context of the other two
patches:

https://lore.kernel.org/r/20220303045029.2645297-7-memxor@gmail.com/
https://lore.kernel.org/r/20220303045029.2645297-8-memxor@gmail.com/

Cheers,
Nathan

> ---
>  include/linux/compiler-clang.h | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index 3c4de9b6c6e3..f1aa41d520bd 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -68,3 +68,25 @@
>  
>  #define __nocfi		__attribute__((__no_sanitize__("cfi")))
>  #define __cficanonical	__attribute__((__cfi_canonical_jump_table__))
> +
> +/*
> + * Turn individual warnings and errors on and off locally, depending
> + * on version.
> + */
> +#define __diag_clang(version, severity, s) \
> +	__diag_clang_ ## version(__diag_clang_ ## severity s)
> +
> +/* Severity used in pragma directives */
> +#define __diag_clang_ignore	ignored
> +#define __diag_clang_warn	warning
> +#define __diag_clang_error	error
> +
> +#define __diag_str1(s)		#s
> +#define __diag_str(s)		__diag_str1(s)
> +#define __diag(s)		_Pragma(__diag_str(clang diagnostic s))
> +
> +#if CONFIG_CLANG_VERSION >= 110000
> +#define __diag_clang_11(s)	__diag(s)
> +#else
> +#define __diag_clang_11(s)
> +#endif
> -- 
> 2.35.1
>