Re: [PATCH v5 2/2] scripts: checkpatch: check unused parameters for function-like macro

[Joe Perches <joe@perches.com>]

On Mon, 2024-04-01 at 14:21 +1300, Barry Song wrote:
> From: Xining Xu <mac.xxn@outlook.com>
> 
> If function-like macros do not utilize a parameter, it might result in a
> build warning.  In our coding style guidelines, we advocate for utilizing
> static inline functions to replace such macros.  This patch verifies
> compliance with the new rule.
> 
> For a macro such as the one below,
> 
>  #define test(a) do { } while (0)
> 
> The test result is as follows.
> 
>  ERROR: Parameter 'a' is not used in function-like macro, please use static
>  inline instead
>  #21: FILE: mm/init-mm.c:20:
>  +#define test(a) do { } while (0)

This is no longer true.
Please update the ERROR->WARN and message as below

Ideally, this would have an update to
Documentation/dev-tools/checkpatch.rst

to describe the new --verbose message type

> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -6040,6 +6040,12 @@ sub process {
>  					CHK("MACRO_ARG_PRECEDENCE",
>  					    "Macro argument '$arg' may be better as '($arg)' to avoid precedence issues\n" . "$herectx");
>  				}
> +
> +# check if this is an unused argument
> +				if ($define_stmt !~ /\b$arg\b/) {
> +					WARN("MACRO_ARG_UNUSED",
> +						"Argument '$arg' is not used in function-like macro\n" . "$herectx");
> +				}