[PATCH v2 1/2] checkpatch: detect unhandled placeholders in cover letters

["Onur Özkan" <work@onurozkan.dev>]

Adds a new check PLACEHOLDER_USE to detect unhandled placeholders.
This prevents sending patch series with incomplete patches (mostly
in cover letters) containing auto generated subject or blurb lines.

These placeholders can be seen on mailing lists. With this change,
checkpatch will emit an error when such text is found.

Signed-off-by: Onur Özkan <work@onurozkan.dev>
---
 scripts/checkpatch.pl | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e722dd6fa8ef..965faee71935 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3340,6 +3340,13 @@ sub process {
 			}
 		}
 
+# Check for auto-generated unhandled placeholder text (mostly for cover letters)
+		if (($in_commit_log || $in_header_lines) &&
+		    $rawline =~ /(?:SUBJECT|BLURB) HERE/) {
+			ERROR("PLACEHOLDER_USE",
+			      "Placeholder text detected\n" . $herecurr);
+		}
+
 # Check for git id commit length and improperly formed commit descriptions
 # A correctly formed commit description is:
 #    commit <SHA-1 hash length 12+ chars> ("Complete commit subject")
-- 
2.51.0