Shift has a higher precedence that mask so warn
when a mask then shift operation is done without
parentheses around the mask.
This test works well for a right shift, but the
left shift is pretty commonly done correctly so
only warn on the right shift.
Signed-off-by: Joe Perches <j...@perches.com>
---
scripts/checkpatch.pl | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d94f5d8..9b474d5 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4478,6 +4478,14 @@ sub process {
}
}
+# check for mask then right shift without a parentheses
+ if ($^V && $^V ge 5.10.0 &&
+ $line =~ /$LvalOrFunc\s*\&\s*($LvalOrFunc)\s*>>/ &&
+ $4 !~ /^\&/) { # $LvalOrFunc may be &foo, ignore if so
+ WARN("MASK_THEN_SHIFT",
+ "Possible precedence defect with mask then right
shift - may need parentheses\n" . $herecurr);
+ }
+
# check for bad placement of section $InitAttribute (e.g.: __initdata)
if ($line =~ /(\b$InitAttribute\b)/) {
my $attr = $1;
--
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