[PATCH RFC] checkpatch: add new cases to commit handling

[Dwaipayan Ray <dwaipayanray1@gmail.com>]

Commit extraction in checkpatch fails in some cases.
One of the most common false positives is a split line
between "commit" and the git SHA of the commit.

Improve commit handling to reduce false positives.

Improvements:
- handle split line between commit and git SHA of commit.
- fix handling of split commit description.

A quick evaluation of 50k commits from v5.4 showed that
the GIT_COMMIT_ID errors dropped from 1032 to 897. Most
of these were split lines between commit and its hash.

Signed-off-by: Dwaipayan Ray <dwaipayanray1@gmail.com>
---
 scripts/checkpatch.pl | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 024514946bed..f5ba2beac008 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2990,6 +2990,16 @@ sub process {
 			if ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)"\)/i) {
 				$orig_desc = $1;
 				$hasparens = 1;
+			} elsif ($line =~ /^\s*[0-9a-f]{5,}\s+\("([^"]+)"\)/i &&
+				 defined $rawlines[$linenr-2] &&
+				 $rawlines[$linenr-2] =~ /\bcommit\s*$/i) {
+				$line =~ /^\s*[0-9a-f]{5,}\s+\("([^"]+)"\)/i;
+				$orig_desc = $1;
+				$hasparens = 1;
+				$space = 0;
+				$short = 0 if ($line =~ /\b[0-9a-f]{12,40}/i);
+				$long = 1 if ($line =~ /\b[0-9a-f]{41,}/i);
+				$case = 0 if ($line =~ /\b[0-9a-f]{5,40}[^A-F]/ && $rawlines[$linenr-2] =~ /\b[Cc]ommit\s*$/);
 			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s*$/i &&
 				 defined $rawlines[$linenr] &&
 				 $rawlines[$linenr] =~ /^\s*\("([^"]+)"\)/) {
@@ -3001,7 +3011,9 @@ sub process {
 				$line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)$/i;
 				$orig_desc = $1;
 				$rawlines[$linenr] =~ /^\s*([^"]+)"\)/;
-				$orig_desc .= " " . $1;
+				my $split_desc = $1;
+				$split_desc = " $split_desc" if ($line =~ /[\w\,\.]$/);
+				$orig_desc .= $split_desc;
 				$hasparens = 1;
 			}
 
-- 
2.27.0