Re: [PATCH v4 2/2] scripts: checkpatch: check unused parameters for function-like macro

From: Joe Perches
Date: Thu Mar 28 2024 - 05:57:59 EST


On Thu, 2024-03-28 at 15:21 +1300, Barry Song wrote:
> From: Xining Xu <mac.xxn@xxxxxxxxxxx>
>
> 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.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -6109,6 +6109,36 @@ sub process {
> WARN("TRAILING_SEMICOLON",
> "macros should not use a trailing semicolon\n" . "$herectx");
> }
> +
> + # match "\s*" rather than "\s+" after the balanced parens, as macro definition with arguments
> + # is not required to have whitespace after arguments
> + if ($dstat =~ /^\+\s*#\s*define\s+$Ident$balanced_parens\s*(\S+.*)(\/[\/*].*)?/) {

I think '(\/[\/*].*)?' doesn't do what you expect
perhaps '(\/[\/\*].*)?'
though I don't know why this should be capture group

> + my $params = $1 || "";


> + my $body = $2 || "";

Should never get the || "" as the 2nd capture group is not optional

> +
> + # get the individual params
> + $params =~ tr/()//d;
> + # remove leading and trailing whitespace
> + $params =~ s/^\s+|\s+$//g;
> +
> + $ctx =~ s/\n*$//;
> + my $cnt = statement_rawlines($ctx);
> + my $herectx = get_stat_here($linenr, $cnt, $here);
> +
> + if ($params ne "") {

probably unnecessary

> + my @paramList = split /,\s*/, $params;

please use split() with parentheses

> + foreach my $param(@paramList) {

maybe
foreach my $param (split(/,/, $params) {
$param = trim($param);
next if ($param =~ /\.\.\.$/);

> + if ($param =~ /\.\.\.$/) {
> + # if the param name ends with "...", skip the check
> + next;
> + }
> + if ($body !~ /\b$param\b/) {
> + WARN("UNUSED_PARAM_IN_MACRO",
> + "Parameter '$param' is not used in function-like macro\n" . "$herectx");
> + }
> + }

It seems this logic is a bit redundant to existing
code and might be better added in the block that starts

(line 6026)
# check if any macro arguments are reused (ignore '...' and 'type')

as that already does each param in a #define and
ignores ... and type