[PATCH] checkpatch: improve handling of email comments

[Dwaipayan Ray]

checkpatch has limited support for parsing email comments. It only
support single name comments or single after address comments.
Whereas, RFC 5322 specifies that comments can be inserted in
between any tokens of the email fields.

Improve comment parsing mechanism in checkpatch.

What is handled now:

- Multiple name/address comments
- Comments anywhere in between name/address
- Nested comments like (John (Doe))


A brief analysis of checkpatch output on v5.0..v5.7 showed that
after these modifications, the number of BAD_SIGN_OFF warnings
came down from 2944 to 1424, and FROM_SIGN_OFF_MISMATCH came
down from 2366 to 2330.

So, a total of 1556 false positives were resolved in total.

Signed-off-by: Dwaipayan Ray <dwaipayanr...@gmail.com>
---
 scripts/checkpatch.pl | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index fab38b493cef..ae8436385fc1 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1183,14 +1183,20 @@ sub parse_email {
                }
        }
 
-       $comment = trim($comment);
+       # Comments in between name like John(A nice chap) Doe
+       while ($name =~ s/\s*($balanced_parens)\s*/ /) {
+               $name_comment .= trim($1);
+       }
        $name = trim($name);
        $name =~ s/^\"|\"$//g;
-       if ($name =~ s/(\s*\([^\)]+\))\s*//) {
-               $name_comment = trim($1);
+
+       # Comments in between address like <john(his account)@doe.com>
+       while ($address =~ s/\s*($balanced_parens)\s*//) {
+               $comment .= trim($1);
        }
        $address = trim($address);
        $address =~ s/^\<|\>$//g;
+       $comment = trim($comment);
 
        if ($name =~ /[^\w \-]/i) { ##has "must quote" chars
                $name =~ s/(?<!\\)"/\\"/g; ##escape quotes
@@ -1205,8 +1211,6 @@ sub format_email {
 
        my $formatted_email;
 
-       $name_comment = trim($name_comment);
-       $comment = trim($comment);
        $name = trim($name);
        $name =~ s/^\"|\"$//g;
        $address = trim($address);
@@ -1216,6 +1220,11 @@ sub format_email {
                $name = "\"$name\"";
        }
 
+       $name_comment = trim($name_comment);
+       $name_comment =~ s/(.+)/ $1/;
+       $comment = trim($comment);
+       $comment =~ s/(.+)/ $1/;
+
        if ("$name" eq "") {
                $formatted_email = "$address";
        } else {
-- 
2.27.0