Re: [Linux-kernel-mentees] [PATCH v2] checkpatch: add new exception to repeated word check

[Dwaipayan Ray <dwaipayanray1@gmail.com>]

On Sat, Oct 17, 2020 at 8:26 AM Joe Perches <joe@perches.com> wrote:
>
> On Wed, 2020-10-14 at 11:35 -0700, Joe Perches wrote:
> > On Wed, 2020-10-14 at 23:42 +0530, Dwaipayan Ray wrote:
> > > On Wed, Oct 14, 2020 at 11:33 PM Joe Perches <joe@perches.com> wrote:
> > > > On Wed, 2020-10-14 at 22:07 +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:
> > > >
> > > > Perhaps instead of adding more content checks so that
> > > > word boundaries are not something like \S but also
> > > > not punctuation so that content like
> > > >
> > > >         git git://
> > > >         @size size
> > > >
> > > > does not match?
> > > >
> > > >
> > > Hi,
> > > So currently the words are trimmed of non alphabets before the check:
> > >
> > > while ($rawline =~ /\b($word_pattern) (?=($word_pattern))/g) {
> > > my $first = $1;
> > > my $second = $2;
> > >
> > > where, the word_pattern is:
> > > my $word_pattern = '\b[A-Z]?[a-z]{2,}\b';
> >
> > I'm familiar.
> >
> > > So do you perhaps recommend modifying this word pattern to
> > > include the punctuation as well rather than trimming them off?
> >
> > Not really, perhaps use the capture group position
> > markers @- @+ or $-[1] $+[1] and $-[2] $+[2] with the
> > substr could be used to see what characters are
> > before and after the word matches.
>
> Perhaps something like:
> ---
>  scripts/checkpatch.pl | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index fab38b493cef..a65eb40a5539 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -3054,15 +3054,25 @@ sub process {
>
>                                 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($second));
>                                 next if ($first eq 'long');
>
> +                               my $start_char = "";
> +                               my $end_char = "";
> +                               $start_char = substr($rawline, $start_pos - 1, 1) if ($start_pos > 0);
> +                               $end_char = substr($rawline, $end_pos, 1) if (length($rawline) > $end_pos);
> +
> +                               next if ($start_char =~ /^\S$/);
> +                               next if ($end_char !~ /^[\.\,\s]?$/);
> +
>                                 if (WARN("REPEATED_WORD",
>                                          "Possible repeated word: '$first'\n" . $herecurr) &&
>                                     $fix) {
>
>

Hi Joe,
Thank you for the insight. I was also doing something similar:

---
 scripts/checkpatch.pl | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index f1a4e61917eb..82497a71ac96 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -595,6 +595,7 @@ our @mode_permission_funcs = (
 );

 my $word_pattern = '\b[A-Z]?[a-z]{2,}\b';
+my $punctuation_chars = '[,:;@\.\-]';

 #Create a search pattern for all these functions to speed up a loop below
 our $mode_perms_search = "";
@@ -3065,6 +3066,21 @@ sub process {
  next if ($first ne $second);
  next if ($first eq 'long');

+ # check for character before and after the word matches
+ my $ca_first = substr($rawline, $-[1]-1, 1);
+ my $cb_first = substr($rawline, $+[1], 1);
+ my $ca_second = substr($rawline, $-[2]-1, 1);
+ my $cb_second = substr($rawline, $+[2], 1);
+
+ if ($ca_first ne $ca_second || $cb_first ne $cb_second) {
+ if ($ca_first =~ /$punctuation_chars/ ||
+     $ca_second =~ /$punctuation_chars/ ||
+     $cb_first =~ /$punctuation_chars/ ||
+     $cb_second =~ /$punctuation_chars/) {
+ next;
+ }
+ }
+
  if (WARN("REPEATED_WORD",
  "Possible repeated word: '$first'\n" . $herecurr) &&
      $fix) {

Does it look okay to you??

Thanks,
Dwaipayan.
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