[patch 130/166] checkpatch: prefer fallthrough; over fallthrough comments

Andrew Morton
2020-04-07T03:11:01Z

From: Joe Perches <joe@perches.com>
Subject: checkpatch: prefer fallthrough; over fallthrough comments

commit 294f69e662d1 ("compiler_attributes.h: Add 'fallthrough' pseudo
keyword for switch/case use") added the pseudo keyword so add a test for
it to checkpatch.

Warn on a patch or use --strict for files.

Link: http://lkml.kernel.org/r/8b6c1b9031ab9f3cdebada06b8d46467f1492d68.camel@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

scripts/checkpatch.pl | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)

--- a/scripts/checkpatch.pl~checkpatch-prefer-fallthrough-over-fallthrough-comments
+++ a/scripts/checkpatch.pl
@@ -2294,6 +2294,19 @@ sub pos_last_openparen {
return length(expand_tabs(substr($line, 0, $last_openparen))) + 1;
}

+sub get_raw_comment {
+ my ($line, $rawline) = @_;
+ my $comment = '';
+
+ for my $i (0 .. (length($line) - 1)) {
+ if (substr($line, $i, 1) eq "$;") {
+ $comment .= substr($rawline, $i, 1);
+ }
+ }
+
+ return $comment;
+}
+
sub process {
my $filename = shift;

@@ -2455,6 +2468,7 @@ sub process {
$sline =~ s/$;/ /g; #with comments as spaces

my $rawline = $rawlines[$linenr - 1];
+ my $raw_comment = get_raw_comment($line, $rawline);

# check if it's a mode change, rename or start of a patch
if (!$in_commit_log &&
@@ -6408,6 +6422,28 @@ sub process {
}
}

+# check for /* fallthrough */ like comment, prefer fallthrough;
+ my @fallthroughs = (
+ 'fallthrough',
+ '@fallthrough@',
+ 'lint -fallthrough[ \t]*',
+ 'intentional(?:ly)?[ \t]*fall(?:(?:s | |-)[Tt]|t)hr(?:ough|u|ew)',
+ '(?:else,?\s*)?FALL(?:S | |-)?THR(?:OUGH|U|EW)[ \t.!]*(?:-[^\n\r]*)?',
+ 'Fall(?:(?:s | |-)[Tt]|t)hr(?:ough|u|ew)[ \t.!]*(?:-[^\n\r]*)?',
+ 'fall(?:s | |-)?thr(?:ough|u|ew)[ \t.!]*(?:-[^\n\r]*)?',
+ );
+ if ($raw_comment ne '') {
+ foreach my $ft (@fallthroughs) {
+ if ($raw_comment =~ /$ft/) {
+ my $msg_level = \&WARN;
+ $msg_level = \&CHK if ($file);
+ &{$msg_level}("PREFER_FALLTHROUGH",
+ "Prefer 'fallthrough;' over fallthrough comment\n" . $herecurr);
+ last;
+ }
+ }
+ }
+
# check for switch/default statements without a break;
if ($perl_version_ok &&
defined $stat &&
_