checkpatch: add --strict check for ifs with unnecessary parentheses

An if statement test like
	if ((foo == bar) && (baz != qux))
can arguably be better written without the parentheses as
	if (foo == bar && baz != qux)

Add a test to find these cases.

Link: http://lkml.kernel.org/r/dcd0561ddd0fa43c51a420d53b550d738bf42001.1502734458.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.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 2287a0bca863bf57ffabaae9de58aab0174826c3..143ab5ca2c4129fe9a4a1df4a2666535e49ea19f 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4496,6 +4496,30 @@ sub process {
                        }
                }
 
+# check for unnecessary parentheses around comparisons in if uses
+               if ($^V && $^V ge 5.10.0 && defined($stat) &&
+                   $stat =~ /(^.\s*if\s*($balanced_parens))/) {
+                       my $if_stat = $1;
+                       my $test = substr($2, 1, -1);
+                       my $herectx;
+                       while ($test =~ /(?:^|[^\w\&\!\~])+\s*\(\s*([\&\!\~]?\s*$Lval\s*(?:$Compare\s*$FuncArg)?)\s*\)/g) {
+                               my $match = $1;
+                               # avoid parentheses around potential macro args
+                               next if ($match =~ /^\s*\w+\s*$/);
+                               if (!defined($herectx)) {
+                                       $herectx = $here . "\n";
+                                       my $cnt = statement_rawlines($if_stat);
+                                       for (my $n = 0; $n < $cnt; $n++) {
+                                               my $rl = raw_line($linenr, $n);
+                                               $herectx .=  $rl . "\n";
+                                               last if $rl =~ /^[ \+].*\{/;
+                                       }
+                               }
+                               CHK("UNNECESSARY_PARENTHESES",
+                                   "Unnecessary parentheses around '$match'\n" . $herectx);
+                       }
+               }
+
 #goto labels aren't indented, allow a single space however
                if ($line=~/^.\s+[A-Za-z\d_]+:(?![0-9]+)/ and
                   !($line=~/^. [A-Za-z\d_]+:/) and !($line=~/^.\s+default:/)) {