linux-kernel - Re: [PATCH v4] checkpatch: add new exception to repeated word check

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Date:   Sat, 17 Oct 2020 21:31:20 +0530
From:   Dwaipayan Ray <dwaipayanray1@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: Re: [PATCH v4] checkpatch: add new exception to repeated word check

On Sat, Oct 17, 2020 at 9:24 PM Joe Perches <joe@...ches.com> wrote:
>
> On Sat, 2020-10-17 at 13:21 +0530, Dwaipayan Ray wrote:
> > Recently, commit 4f6ad8aa1eac ("checkpatch: move repeated word test")
> > moved the repeated word test to check for more file types. But after
> > this, if checkpatch.pl is run on MAINTAINERS, it generates several
> > new warnings of the type:
> >
> > WARNING: Possible repeated word: 'git'
> >
> > For example:
> > WARNING: Possible repeated word: 'git'
> > +T:   git git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml.git
> >
> > So, the pattern "git git://..." is a false positive in this case.
> >
> > There are several other combinations which may produce a wrong
> > warning message, such as "@size size", ":Begin begin", etc.
> >
> > Extend repeated word check to compare the characters before and
> > after the word matches. If the preceding or succeeding character
> > belongs to the exception list, the warning is avoided.
>
> Not true.
>
> This excludes any non-space character before the first word
> and excludes space or punctuation after the second word.
>
> This also adds case insensitive word matching.
>

Right, I didn't change the commit message. I will update it
properly.

> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -3052,19 +3052,30 @@ sub process {
> >
> >  # check for repeated words separated by a single space
> >               if ($rawline =~ /^\+/ || $in_commit_log) {
> > +                     pos($rawline) = 1 if (!$in_commit_log);
> >                       while ($rawline =~ /\b($word_pattern) (?=($word_pattern))/g) {
> >
> >                               my $first = $1;
> >                               my $second = $2;
> > -
> > +                             my $start_pos = $-[1];
> > +                             my $end_pos = $+[2];
> >                               if ($first =~ /(?:struct|union|enum)/) {
> >                                       pos($rawline) += length($first) + length($second) + 1;
> >                                       next;
> >                               }
> >
> > -                             next if ($first ne $second);
> > +                             next if (lc($first) ne lc($second));
>
> case-insensitive matching
>
> >                               next if ($first eq 'long');
> >
> > +                             # check for character before and after the word matches
> > +                             my $start_char = '';
> > +                             my $end_char = '';
> > +                             $start_char = substr($rawline, $start_pos - 1, 1) if ($start_pos > ($in_commit_log? 0 : 1));
> > +                             $end_char = substr($rawline, $end_pos, 1) if ($end_pos < length($rawline));
> > +
> > +                             next if ($start_char =~ /^\S$/);
>
> non-space
>
> > +                             next if ($end_char !~ /^[\.\,\;\?\!\s]?$/);
>
> space or punctuation.
>
> trivia:
>
> I believe using index would be ~50% faster than !~ here
> Perhaps more readable too.
>
>                                 next if (index(" \t.,;?!", $end_char) >= 0);
>
Yes, it looks better. Thanks for the suggestion.

I will send in a new iteration after all of this is incorporated.

Thank you,
Dwaipayan.