[PATCH] checkpatch: avoid default n

[Miles Chen]

This change reports a warning when "default n" is used.

I have seen several "remove default n" patches, so I think
it might be helpful to add this test in checkpatch.

tested:
WARNING: 'default n' is the default value, no need to write it explicitly.
+       default n

Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
---
 scripts/checkpatch.pl | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 342c7c781ba5..6531b5757c6b 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3005,6 +3005,13 @@ sub process {
 			     "Use of boolean is deprecated, please use bool instead.\n" . $herecurr);
 		}
 
+# avoid redundant 'default n'
+		if ($realfile =~ /Kconfig/ &&
+		    $line =~ /^\+\s*\bdefault n\b/) {
+			WARN("AVOID_DEFAULT_N",
+			     "'default n' is the default value, no need to write it explicitly.\n" . $herecurr);
+		}
+
 		if (($realfile =~ /Makefile.*/ || $realfile =~ /Kbuild.*/) &&
 		    ($line =~ /\+(EXTRA_[A-Z]+FLAGS).*/)) {
 			my $flag = $1;
-- 
2.18.0