linux-kernel - [PATCH] checkpatch: Add test for comma use that should be semicolon

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Date:   Wed, 19 Aug 2020 14:22:10 -0700
From:   Joe Perches <joe@...ches.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andy Whitcroft <apw@...dowen.org>
Subject: [PATCH] checkpatch: Add test for comma use that should be semicolon

There are commas used as statement terminations that should typically
have used semicolons instead.  Only direct assignments or use of a single
function or value on a single line are detected by this test.

e.g.:
	foo = bar(),		/* typical use is semicolon not comma */
	bar = baz();

Add an imperfect test to detect these comma uses.

No false positives were found in testing, but many types of false negatives
are possible.

e.g.:
	foo = bar() + 1,	/* comma use, but not direct assignment */
	bar = baz();

Signed-off-by: Joe Perches <joe@...ches.com
---
 scripts/checkpatch.pl | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl= 
index 60d4a79674b6..93b99809df07 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4936,6 +4936,17 @@ sub process {
 			}
 		}
 
+# check if a statement with a comma should be two statements like:
+#	foo = bar(),	/* comma should be semicolon */
+#	bar = baz();
+		if (defined($stat) &&
+		    $stat =~ /^\+\s*(?:$Lval\s*$Assignment\s*)?$FuncArg\s*,\s*(?:$Lval\s*$Assignment\s*)?$FuncArg\s*;\s*$/) {
+			my $cnt = statement_rawlines($stat);
+			my $herectx = get_stat_here($linenr, $cnt, $here);
+			WARN("SUSPECT_COMMA_SEMICOLON",
+			     "Possible comma where semicolon could be used\n" . $herectx);
+		}
+
 # return is not a function
 		if (defined($stat) && $stat =~ /^.\s*return(\s*)\(/s) {
 			my $spacing = $1;