"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 <[email protected]>
---
scripts/checkpatch.pl | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e14dcdb..5fca1da 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -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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