checkpatch: check for if's with unnecessary parentheses

If statements don't need multiple parentheses around tested comparisons
like "if ((foo == bar))".

An == comparison maybe a sign of an intended assignment, so emit a
slightly different message if so.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 3e0b3f4d3420..57f10db4accd 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3254,6 +3254,20 @@ sub process {
                         }
                 }
 
+# if statements using unnecessary parentheses - ie: if ((foo == bar))
+                if ($^V && $^V ge 5.10.0 &&
+                    $line =~ /\bif\s*((?:\(\s*){2,})/) {
+                        my $openparens = $1;
+                        my $count = $openparens =~ tr@\(@\(@;
+                        my $msg = "";
+                        if ($line =~ /\bif\s*(?:\(\s*){$count,$count}$LvalOrFunc\s*($Compare)\s*$LvalOrFunc(?:\s*\)){$count,$count}/) {
+                                my $comp = $4;  #Not $1 because of $LvalOrFunc
+                                $msg = " - maybe == should be = ?" if ($comp eq "==");
+                                WARN("UNNECESSARY_PARENTHESES",
+                                     "Unnecessary parentheses$msg\n" . $herecurr);
+                        }
+                }
+
 # Return of what appears to be an errno should normally be -'ve
                 if ($line =~ /^.\s*return\s*(E[A-Z]*)\s*;/) {
                         my $name = $1;