linux-kernel - Re: [PATCH v2 2/2] checkpatch: 3 use-cases for --debug rx=1 option

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Message-ID: <CAJfuBxwEeLLoiUttroUCj4wUaWvBUqiXyHha4RgQLcxmy81_5g@mail.gmail.com>
Date: Wed, 29 Oct 2025 13:20:28 -0600
From: jim.cromie@...il.com
To: Joe Perches <joe@...ches.com>
Cc: linux-kernel@...r.kernel.org, akpm@...uxfoundation.org, 
	Andy Whitcroft <apw@...onical.com>, Dwaipayan Ray <dwaipayanray1@...il.com>, 
	Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: Re: [PATCH v2 2/2] checkpatch: 3 use-cases for --debug rx=1 option

On Sun, Oct 26, 2025 at 5:40 PM Joe Perches <joe@...ches.com> wrote:
>
> On Sun, 2025-10-26 at 14:21 -0600, Jim Cromie wrote:
> > Use the drx_print() helper in 3 cases inside code which counts macro
> > arg expansions.
> []
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -6078,9 +6078,17 @@ sub process {
> >                               next if ($arg =~ /\.\.\./);
> >                               next if ($arg =~ /^type$/i);
> >                               my $tmp_stmt = $define_stmt;
> > -                             $tmp_stmt =~ s/\b(__must_be_array|offsetof|sizeof|sizeof_field|__stringify|typeof|__typeof__|__builtin\w+|typecheck\s*\(\s*$Type\s*,|\#+)\s*\(*\s*$arg\s*\)*\b//g;
> > -                             $tmp_stmt =~ s/\#+\s*$arg\b//g;
> > -                             $tmp_stmt =~ s/\b$arg\s*\#\#//g;
> > +
> > +                             $tmp_stmt =~ s/\#+\s*$arg\b/drx_print("'#|## arg' catenations")/ge;
> > +                             $tmp_stmt =~ s/\b$arg\s*\#\#/drx_print("'arg ##' catenations");/ge;
>
> stray trailing ; in the replacement ?
>
> > +                             $tmp_stmt =~ s{
> > +                                     \b(__must_be_array|offsetof|sizeof|sizeof_field|
> > +                                        __stringify|typeof|__typeof__|__builtin\w+|
> > +                                        typecheck\s*\(\s*$Type\s*,|\#+)\s*\(*\s*$arg\s*\)*\b }
>
> This might be easier to read using a qr but I'm not sure the
> embedded capture groups and their use in drx_print is sensible
> as it doesn't seem extensible.
>

yes, the extra whitespace is better.
I will play with qr// see if the captures work the same.

> our $stmt_stripper = qr{\b(
>                 __must_be_array |
>                 offsetof | typeof | __typeof__ |
>                 sizeof | sizeof_field |
>                 __builtin\w+
>                 typecheck\s*\(\s*$Type\s*,|\#+)\s*\(*\s*$arg\s*\)\(*\s*$arg\s*\)*
>
> > +                             {
> > +                                     drx_print("-arg-inspections-");
> > +                             }xge;
> > +
> >                               my $use_cnt = () = $tmp_stmt =~ /\b$arg\b/g;
> >                               if ($use_cnt > 1) {
> >                                       CHK("MACRO_ARG_REUSE",
>
> Back with I suggested this a dozen years ago I thought it was overkill.
> Maybe it is and the whole test should be offed.
>

I am now playing with an __lvalue(x) macro,
based upon  __must_be_array(x),
it is a compile-time check, so it gives a high-quality signal to checkpatch
if x is an lval, the multiple expansion warnings can be silenced for x.

So if this works out, we could take off the wart, rather than the finger.

> https://lore.kernel.org/lkml/1352198139.16194.21.camel@joe-AO722/