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

Andrew Morton
2014-06-19T20:18:40Z

On Wed, 18 Jun 2014 10:44:44 -0700 Joe Perches <joe@perches.com> 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@perches.com>
> ---
>
> V2: The previous patch had a few too many false positives
> on styles that should be acceptable.

Previous patch is now in mainline, so I did this:

From: Joe Perches <joe@perches.com>
Subject: checkpatch: reduce false positives when checking void function return statements

The previous patch had a few too many false positives on styles that
should be acceptable.

Signed-off-by: Joe Perches <joe@perches.com>
Tested-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

scripts/checkpatch.pl | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff -puN scripts/checkpatch.pl~checkpatch-reduce-false-positives-when-checking-void-function-return-statements scripts/checkpatch.pl
--- a/scripts/checkpatch.pl~checkpatch-reduce-false-positives-when-checking-void-function-return-statements
+++ a/scripts/checkpatch.pl
@@ -3484,12 +3484,17 @@ sub process {
}
}

-# unnecessary return in a void function? (a single leading tab, then return;)
- if ($sline =~ /^\+\treturn\s*;\s*$/ &&
- $prevline =~ /^\+/) {
+# unnecessary return in a void function
+# at end-of-function, with the previous line a single leading tab, then return;
+# and the line before that not a goto label target like "out:"
+ if ($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" . $herecurr);
- }
+ "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 &&
_