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Date:   Wed, 11 Oct 2023 14:44:17 -0700
From:   Dan Williams <dan.j.williams@intel.com>
To:     Max Kellermann <max.kellermann@ionos.com>, <linux@roeck-us.net>,
        <joe@perches.com>, <gregkh@linuxfoundation.org>,
        Jonathan Corbet <corbet@lwn.net>
CC:     Max Kellermann <max.kellermann@ionos.com>,
        <workflows@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3] Documentation/process/coding-style.rst: space around
 const
Message-ID: <65271731e25f4_7258329472@dwillia2-xfh.jf.intel.com.notmuch>
References: <20231010125832.1002941-1-max.kellermann@ionos.com>
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Max Kellermann wrote:
> There are currently no rules on the placement of "const", but a recent
> code submission revealed that there is clearly a preference for spaces
> around it.
> 
> checkpatch.pl has no check at all for this; though it does sometimes
> complain, but only because it erroneously thinks that the "*" (on
> local variables) is an unary dereference operator, not a pointer type.
> 
> Current coding style for const pointers-to-pointers:
> 
>  "*const*": 2 occurrences
>  "* const*": 3
>  "*const *": 182
>  "* const *": 681
> 
> Just const pointers:
> 
>  "*const": 2833 occurrences
>  "* const": 16615
> 
> Link: https://lore.kernel.org/r/264fa39d-aed6-4a54-a085-107997078f8d@roeck-us.net/
> Link: https://lore.kernel.org/r/f511170fe61d7e7214a3a062661cf4103980dad6.camel@perches.com/
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
> ---
> V1 -> V2: removed "volatile" on gregkh's request.
> V2 -> V3: moved patch changelog below the "---" line
> ---
>  Documentation/process/coding-style.rst | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
> index 6db37a46d305..71d62d81e506 100644
> --- a/Documentation/process/coding-style.rst
> +++ b/Documentation/process/coding-style.rst
> @@ -271,6 +271,17 @@ adjacent to the type name.  Examples:
>  	unsigned long long memparse(char *ptr, char **retptr);
>  	char *match_strdup(substring_t *s);
>  
> +Use space around the ``const`` keyword (except when adjacent to
> +parentheses).  Example:
> +
> +.. code-block:: c
> +
> +	const void *a;
> +	void * const b;
> +	void ** const c;
> +	void * const * const d;
> +	int strcmp(const char *a, const char *b);
> +
>  Use one space around (on each side of) most binary and ternary operators,
>  such as any of these::

I notice that clang-format reflows that example to:

     const void *a;
     void *const b;
     void **const c;
     void *const *const d;
     int strcmp(const char *a, const char *b);

...but someone more clang-format savvy than me would need to propose the
changes to the kernel's .clang-format template to match the style
suggestion.