linux-kernel - Re: [PATCH V2] checkpatch: Warn on unnecessary void function return statements

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Date:	Wed, 18 Jun 2014 12:59:09 -0700
From:	Anish Bhatt <anish@...lsio.com>
To:	Joe Perches <joe@...ches.com>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH V2] checkpatch: Warn on unnecessary void function return
 statements

On Wed 18 Jun 2014 10:44:44 AM PDT, Joe Perches wrote:
> With some exceptions, warn on void functions that end with a
> "return;", because it's unnecessary.
>
> Check the closing brace at the start of a line.
> If the line before that has a single tab, then return;
> look at the line before that.  If it's not a label,
> emit a warning.
>
> So, emit a warning on:
>
> void function(...)
> {
> 	[...]
> 	return;
> }
>
> but do not emit a warning on the below because
> gcc requires any statement (including a bare
> semicolon) before the closing function brace:
>
> void function(...)
> {
> 	[...]
> 		goto label;
> 	[...]
>
> label:
> 	return;
> }
>
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
>
> V2: The previous patch had a few too many false positives
>     on styles that should be acceptable.
>
>  scripts/checkpatch.pl | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 862cc7a..b191c88 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -3470,6 +3470,18 @@ sub process {
>  			}
>  		}
>
> +# unnecessary return in a void function
> +# at end-of-function, with the previous line a single leading tab, then return;
> +# and the line before that not a goto label target like "out:"
> +		if ($sline =~ /^[ \+]}\s*$/ &&
> +		    $prevline =~ /^\+\treturn\s*;\s*$/ &&
> +		    $linenr >= 3 &&
> +		    $lines[$linenr - 3] =~ /^[ +]/ &&
> +		    $lines[$linenr - 3] !~ /^[ +]\s*$Ident\s*:/) {
> +			WARN("RETURN_VOID",
> +			     "void function return statements are not generally useful\n" . $hereprev);
> +               }
> +
>  # if statements using unnecessary parentheses - ie: if ((foo == bar))
>  		if ($^V && $^V ge 5.10.0 &&
>  		    $line =~ /\bif\s*((?:\(\s*){2,})/) {
>
>

Confirming, no longer hitting previous false positives for me.
-Anish

--
As long as the music's loud enough, we won't hear the world falling 
apart.

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