[PATCH v7] checkpatch: add fix option for LOGICAL_CONTINUATIONS

[Aditya Srivastava]

Currently, checkpatch warns if logical continuations are placed at the
start of a line and not at the end of previous line.

E.g., running checkpatch on commit 3485507fc272 ("staging:
bcm2835-camera: Reduce length of enum names") reports:

CHECK:LOGICAL_CONTINUATIONS: Logical continuations should be on the
previous line
+	if (!ret
+	    && camera_port ==

Provide a simple fix by inserting logical operator at the last
non-comment, non-whitespace char of the previous line and removing from
current line, if both the lines are additions(ie start with '+')

Signed-off-by: Aditya Srivastava <yashsri421@xxxxxxxxx>
---
changes in v2: quote $operator at substitution

changes in v3: add a check for previous line ending with comment;
If so, insert $operator at the last non-comment, non-whitespace char of the previous line

changes in v4: improve the matching mechanism by matching line termination at comment or white space;
insert the operator before comments (if any) separated by a whitespace;
append the comment and its pre-whitespace after the inserted operator (if comment was present),
ie if no comment was present nothing will be inserted after the operator

changes in v5: improve regex for comment and line end with '$;'

changes in v6: remove if-check; modify commit message

changes in v7: add an extra '$' symbol at '$fixed[$fixlinenr - 1]' regex substitution to ensure match at line end

 scripts/checkpatch.pl | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 5b1a5a65e69a..fb3c50e0bde2 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3553,8 +3553,16 @@ sub process {
 
 # check for && or || at the start of a line
 		if ($rawline =~ /^\+\s*(&&|\|\|)/) {
-			CHK("LOGICAL_CONTINUATIONS",
-			    "Logical continuations should be on the previous line\n" . $hereprev);
+			my $operator = $1;
+			if (CHK("LOGICAL_CONTINUATIONS",
+				"Logical continuations should be on the previous line\n" . $hereprev) &&
+			    $fix && $prevrawline =~ /^\+/) {
+				# insert logical operator at last non-comment, non-whitepsace char on previous line
+				$prevline =~ /[\s$;]*$/;
+				my $line_end = substr($prevrawline, $-[0]);
+				$fixed[$fixlinenr - 1] =~ s/\Q$line_end\E$/ $operator$line_end/;
+				$fixed[$fixlinenr] =~ s/\Q$operator\E\s*//;
+			}
 		}
 
 # check indentation starts on a tab stop
-- 
2.17.1