linux-kernel - [PATCH] checkpatch: Add exception to return then else test

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Date:	Wed, 24 Sep 2014 22:03:54 -0700
From:	Joe Perches <joe@...ches.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Elshad Mustafayev <elshadimo@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...IV.linux.org.uk>,
	Andy Whitcroft <apw@...onical.com>
Subject: [PATCH] checkpatch: Add exception to return then else test

Add an exception to the return before else warning
when the line following it is also a return like:

	if (foo)
		return bar;
	else
		return baz;

This form of a test then return is at least as readable as

	if (foo)
		return bar;
	return baz;

so don't emit a warning on the first form.

Signed-off-by: Joe Perches <joe@...ches.com>
Reported-by: Al Viro <viro@...IV.linux.org.uk>
---
> > Just what makes the replacement easier to follow?
> > 	if (foo)
> > 		return bar;
> > 	else
> > 		return baz;
> > is no less idiomatic than
> > 	if (foo)
> > 		return bar;
> > 	return baz;
> > 
> > Al, really annoyed by how the words "coding style issue" are getting used as
> > a magic incantation...
> 
> I agree.
> 
> I'll see about updating checkpatch to avoid warning on it

 scripts/checkpatch.pl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 74bba23..52a223e 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2641,10 +2641,14 @@ sub process {
 		next if ($realfile !~ /\.(h|c)$/);
 
 # check indentation of any line with a bare else
+# (but not if it is a multiple line "if (foo) return bar; else return baz;")
 # if the previous line is a break or return and is indented 1 tab more...
 		if ($sline =~ /^\+([\t]+)(?:}[ \t]*)?else(?:[ \t]*{)?\s*$/) {
 			my $tabs = length($1) + 1;
-			if ($prevline =~ /^\+\t{$tabs,$tabs}(?:break|return)\b/) {
+			if ($prevline =~ /^\+\t{$tabs,$tabs}break\b/ ||
+			    ($prevline =~ /^\+\t{$tabs,$tabs}return\b/ &&
+			     defined $lines[$linenr] &&
+			     $lines[$linenr] !~ /^[ \+]\t{$tabs,$tabs}return/)) {
 				WARN("UNNECESSARY_ELSE",
 				     "else is not generally useful after a break or return\n" . $hereprev);
 			}


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