----- Original Message -----
> From: "Joe Perches" <j...@perches.com>
> To: "Viresh Kumar" <viresh.ku...@linaro.org>
> Cc: "Andrew Morton" <a...@linux-foundation.org>, "Dan Carpenter"
> <dan.carpen...@oracle.com>, "Greg KH"
> <gre...@linuxfoundation.org>, "LKML" <linux-kernel@vger.kernel.org>, "Mike
> Holmes" <mike.hol...@linaro.org>,
> nmo...@kalray.eu
> Sent: Thursday, 27 August, 2015 5:05:37 AM
> Subject: Re: [PATCH] checkpatch: add --strict "pointer comparison to NULL"
> test
>
> 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 = "<";
> + }
I like the concept but are you sure about this? I think the "=" should be added
or removed. If a < b, b > a, not b >= a.
Nicolas
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