[Linux-kernel-mentees] [PATCH] checkpatch: add new exceptions to repeated word check

[Dwaipayan Ray]

On Fri, Oct 16, 2020 at 11:46 PM Dwaipayan Ray <dwaipayanray1 at gmail.com> 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.
>
> Suggested-by: Joe Perches <joe at perches.com>
> Suggested-by: Lukas Bulwahn <lukas.bulwahn at gmail.com>
> Signed-off-by: Dwaipayan Ray <dwaipayanray1 at gmail.com>
> ---
>  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) {
> --
> 2.27.0
>
Hi,
This patch is followed from the discussion at
https://lore.kernel.org/linux-kernel-mentees/7d8c7d80aa7b0524cca49a6dfe24e878bea6ab12.camel@perches.com/
, where Joe suggested that instead of hard coding the
particular words, we can check the surrounding
characters instead for punctuations and ingore them.

Please let me know if any changes are needed.

Thanks,
Dwaipayan.