checkpatch: add constant comparison on left side test (c5595fa2) · Commits · 戴 / 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:

Joe 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:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

+29 −0

Original line number	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
		if ($sline =~ /\breturn(?:\s$+\s\|\s+)(E[A-Z]+)(?:\s$+\s\|\s*)[;:,]/) {
		my $name = $1;

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