[PATCH v2 34/59] checkpatch: dont warn about unused macro arg on empty body

[Joe Perches]

On Thu, 2025-03-20 at 12:52 -0600, Jim Cromie wrote:
> we currently get:
>   WARNING: Argument 'name' is not used in function-like macro
> on:
>   #define DRM_CLASSMAP_USE(name)  /* nothing here */
> 
> Following this advice is wrong here, and shouldn't be fixed by
> ignoring args altogether; the macro should properly fail if invoked
> with 0 or 2+ args.
> 
> cc: Andy Whitcroft <apw at canonical.com>
> cc: Joe Perches <joe at perches.com>
> cc: Dwaipayan Ray <dwaipayanray1 at gmail.com>
> cc: Lukas Bulwahn <lukas.bulwahn at gmail.com>
> Signed-off-by: Jim Cromie <jim.cromie at gmail.com>

Completely sensible, thanks Jim.

> ---
>  scripts/checkpatch.pl | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 7b28ad331742..0c4f578ea6e7 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -6037,7 +6037,7 @@ sub process {
>  				}
>  
>  # check if this is an unused argument
> -				if ($define_stmt !~ /\b$arg\b/) {
> +				if ($define_stmt !~ /\b$arg\b/ && $define_stmt) {
>  					WARN("MACRO_ARG_UNUSED",
>  					     "Argument '$arg' is not used in function-like macro\n" . "$herectx");
>  				}