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.

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

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index ede55af..2b32816 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/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 &&