On Thu, 2015-08-27 at 07:49 +0530, Viresh Kumar wrote:
> Few colleagues asked me why isn't checkpatch warning for (NULL == ptr)
> or (NULL != ptr) checks, as it warns for (ptr == NULL) and (ptr != NULL).
>
> Did you miss it? or was it intentional ?
I didn't miss it.
NULL == foo is relatively unusual and not really worth the
bother.
And because most likely, "CONST test variable" checks like
NULL != foo
and
0 < bar
should probably be a separate test.
Something like:
---
scripts/checkpatch.pl | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e14dcdb..457ddef 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4231,6 +4231,29 @@ sub process {
}
}
+# comparisons with a constant on the left
+ if ($^V && $^V ge 5.10.0 &&
+ $line =~
/\b($Constant|[A-Z_]+)\s*($Compare)\s*($LvalOrFunc)/) {
+ my $const = $1;
+ my $comp = $2;
+ my $to = $3;
+ my $newcomp = $comp;
+ if (WARN("CONSTANT_COMPARISON",
+ "Comparisons should place the constant on the
right side of the test\n" . $herecurr) &&
+ $fix) {
+ if ($comp eq "<") {
+ $newcomp = ">=";
+ } elsif ($comp eq "<=") {
+ $newcomp = ">";
+ } elsif ($comp eq ">") {
+ $newcomp = "<=";
+ } elsif ($comp eq ">=") {
+ $newcomp = "<";
+ }
+ $fixed[$fixlinenr] =~
s/\(\s*\Q$const\E\s*$Compare\s*\Q$to\E\s*\)/($to $newcomp $const)/;
+ }
+ }
+
# Return of what appears to be an errno should normally be negative
if ($sline =~
/\breturn(?:\s*\(+\s*|\s+)(E[A-Z]+)(?:\s*\)+\s*|\s*)[;:,]/) {
my $name = $1;
--
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