[PATCH 5.10 1/2] checkpatch: add new exception to repeated word check

[Carlos Llamas <cmllamas@xxxxxxxxxx>]

From: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx>

commit 1db81a682a2f2a664489c4e94f3b945f70a43a13 upstream.

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 there is a non whitespace character before the first word or a non
whitespace character excluding punctuation characters after the second
word, then the check is skipped and the warning is avoided.

Also add case insensitive word matching to the repeated word check.

Link: https://lore.kernel.org/linux-kernel-mentees/81b6a0bb2c7b9256361573f7a13201ebcd4876f1.camel@xxxxxxxxxxx/
Link: https://lkml.kernel.org/r/20201017162732.152351-1-dwaipayanray1@xxxxxxxxx
Signed-off-by: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx>
Suggested-by: Joe Perches <joe@xxxxxxxxxxx>
Suggested-by: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
Acked-by: Joe Perches <joe@xxxxxxxxxxx>
Cc: Aditya Srivastava <yashsri421@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
---
 scripts/checkpatch.pl | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0ad235ee96f9..a83e5f0088bb 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3050,19 +3050,30 @@ 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($second));
 				next if ($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$/);
+				next if (index(" \t.,;?!", $end_char) == -1);
+
 				if (WARN("REPEATED_WORD",
 					 "Possible repeated word: '$first'\n" . $herecurr) &&
 				    $fix) {
-- 
2.43.0.472.g3155946c3a-goog