Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c5595fa2 authored by Joe Perches's avatar Joe Perches Committed by Linus Torvalds
Browse files

checkpatch: add constant comparison on left side test 



"CONST <comparison> variable" checks like:

        if (NULL != foo)
and
        while (0 < bar(...))

where a constant (or what appears to be a constant like an upper case
identifier) is on the left of a comparison are generally preferred to be
written using the constant on the right side like:

        if (foo != NULL)
and
        while (bar(...) > 0)

Add a test for this.

Add a --fix option too, but only do it when the code is immediately
surrounded by parentheses to avoid misfixing things like "(0 < bar() +
constant)"

Signed-off-by: default avatarJoe Perches <joe@perches.com>
Cc: Nicolas Morey Chaisemartin <nmorey@kalray.eu>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 54507b51

scripts/checkpatch.pl

+29 −0
Original line number Original line Diff line number Diff line
@@ -4231,6 +4231,35 @@ sub process { 
			}

			}

		}

		}





# comparisons with a constant or upper case identifier on the left

#	avoid cases like "foo + BAR < baz"

#	only fix matches surrounded by parentheses to avoid incorrect

#	conversions like "FOO < baz() + 5" being "misfixed" to "baz() > FOO + 5"

		if ($^V && $^V ge 5.10.0 &&

		    $line =~ /^\+(.*)\b($Constant|[A-Z_][A-Z0-9_]*)\s*($Compare)\s*($LvalOrFunc)/) {

			my $lead = $1;

			my $const = $2;

			my $comp = $3;

			my $to = $4;

			my $newcomp = $comp;

			if ($lead !~ /$Operators\s*$/ &&

			    $to !~ /^(?:Constant|[A-Z_][A-Z0-9_]*)$/ &&

			    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

# Return of what appears to be an errno should normally be negative

		if ($sline =~ /\breturn(?:\s*\(+\s*|\s+)(E[A-Z]+)(?:\s*\)+\s*|\s*)[;:,]/) {

		if ($sline =~ /\breturn(?:\s*\(+\s*|\s+)(E[A-Z]+)(?:\s*\)+\s*|\s*)[;:,]/) {

			my $name = $1;

			my $name = $1;