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: 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>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 97ee377..f2a1131 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4231,6 +4231,35 @@
}
}
+# 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;