Re: [PATCH] kconfig: shorten the temporary directory name for cc-option

[Nicolas Schier]

On Tue 19 Jul 2022 11:35:39 +0900 Masahiro Yamada wrote:
> Date:   Tue, 19 Jul 2022 11:35:39 +0900
> From: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> To: linux-kbuild@xxxxxxxxxxxxxxx
> Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH] kconfig: shorten the temporary directory name for cc-option
> Message-Id: <20220719023539.2199045-1-masahiroy@xxxxxxxxxx>
> X-Mailer: git-send-email 2.34.1
> X-Mailing-List: linux-kbuild@xxxxxxxxxxxxxxx
> 
> The cc-option macro creates the temporary directory, .tmp_$$$$, which
> is expanded into .tmp_<PID><PID>, but the second <PID> is redundant.
> (<PID> is the process ID of the sub-shell)
> 
> If it were the Makefile code, .tmp_$$$$ would be the correct code.
> (see the TMPOUT macro in scripts/Malefile.compiler)

Typo: Malefile -> Makefile

> 
> In Makefile, '$$' is an escape sequence of '$'. Make expands '$$$$'
> into '$$', then shell expands it into the process ID.
> 
> This does not apply to Kconfig because Kconfig requires variable
> references to be enclosed by curly braces, like ${variable}.
> The '$' that is not followed by '{' loses its special function.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---

Tested-by: Nicolas Schier <nicolas@xxxxxxxxx>

> 
>  scripts/Kconfig.include | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index 0496efd6e117..c1f4222d223d 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -25,7 +25,7 @@ failure = $(if-success,$(1),n,y)
>  
>  # $(cc-option,<flag>)
>  # Return y if the compiler supports <flag>, n otherwise
> -cc-option = $(success,mkdir .tmp_$$$$; trap "rm -rf .tmp_$$$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$$$/tmp.o)
> +cc-option = $(success,mkdir .tmp_$$; trap "rm -rf .tmp_$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
>  
>  # $(ld-option,<flag>)
>  # Return y if the linker supports <flag>, n otherwise
> -- 
> 2.34.1

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