linux-kernel - [PATCH] checkpatch: warn on unnecessary else after return or break

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Date:	Sun, 08 Jun 2014 21:11:22 -0700
From:	Joe Perches <joe@...ches.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andy Whitcroft <apw@...onical.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] checkpatch: warn on unnecessary else after return or break

Using an else following a break or return can unnecessarily
indent code blocks.

ie:
	for (i = 0; i < 100; i++) {
		int foo = bar();
		if (foo < 1)
			break;
		else
			usleep(1);
	}

is generally better written as:

	for (i = 0; i < 100; i++) {
		int foo = bar();
		if (foo < 1)
			break;
		usleep(1);
	}

Warn when a bare else statement is preceded by a
break or return indented 1 tab more than the else.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 scripts/checkpatch.pl | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 010b18e..9059fd0 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2342,6 +2342,16 @@ sub process {
 # check we are in a valid C source file if not then ignore this hunk
 		next if ($realfile !~ /\.(h|c)$/);
 
+# check indentation of any line with a bare else
+# 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/) {
+				WARN("UNNECESSARY_ELSE",
+				     "else is not generally useful after a break or return\n" . $hereprev);
+			}
+		}
+
 # discourage the addition of CONFIG_EXPERIMENTAL in #if(def).
 		if ($line =~ /^\+\s*\#\s*if.*\bCONFIG_EXPERIMENTAL\b/) {
 			WARN("CONFIG_EXPERIMENTAL",


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