linux-kernel - [PATCH] Coccinelle: Add a SmPL script for the reconsideration of specific combinations of assignment and return statements

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Message-ID: <4977fb04-cc29-3861-0aaf-cd93a0b0b1c7@web.de>
Date:   Wed, 25 Sep 2019 13:33:45 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Julia Lawall <julia.lawall@...6.fr>,
        Coccinelle <cocci@...teme.lip6.fr>,
        kernel-janitors@...r.kernel.org,
        Gilles Muller <Gilles.Muller@...6.fr>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nicolas Palix <nicolas.palix@...g.fr>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Allison Randal <allison@...utok.net>,
        Enrico Weigelt <lkml@...ux.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>
Subject: [PATCH] Coccinelle: Add a SmPL script for the reconsideration of
 specific combinations of assignment and return statements

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Wed, 25 Sep 2019 11:55:24 +0200

Values from expressions were occasionally assigned to local variables
before they will be returned by the subsequent statement.
Such expressions can be directly specified in the return statement instead.

Adjust affected source code by the means of the semantic patch language
(Coccinelle software).

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 .../coccinelle/misc/move_code_to_return.cocci | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 scripts/coccinelle/misc/move_code_to_return.cocci

diff --git a/scripts/coccinelle/misc/move_code_to_return.cocci b/scripts/coccinelle/misc/move_code_to_return.cocci
new file mode 100644
index 000000000000..78cdf84f9aaa
--- /dev/null
+++ b/scripts/coccinelle/misc/move_code_to_return.cocci
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+/// Return expressions directly instead of assigning them to
+/// local variables immediately before affected statements.
+//
+// Keywords: return statements variable assignments coding style
+// Confidence: Medium
+
+virtual patch
+
+@...lacement1 depends on patch@
+expression x;
+identifier f, rc;
+local idexpression lrc;
+type rt;
+@@
+ rt f(...)
+ {
+ ... when any
+ if (...)
+-{
+-lrc@rc = x;
+ return
+-       rc
++       x
+ ;
+-}
+ ... when any
+ }
+
+@...lacement2 depends on patch@
+expression x;
+identifier f, rc;
+local idexpression lrc;
+type rt;
+@@
+ rt f(...)
+ {
+ ... when any
+-lrc@rc = x;
+ return
+-       rc
++       x
+ ;
+ ... when any
+ }
+
+@...etion2 depends on patch@
+identifier replacement2.f, replacement2.rc;
+type replacement2.rt, t;
+@@
+ rt f(...)
+ {
+ ... when any
+-t rc;
+ ... when != rc
+ }
+
+@...etion1 depends on patch@
+identifier replacement1.f, replacement1.rc;
+type replacement1.rt, t;
+@@
+ rt f(...)
+ {
+ ... when any
+-t rc;
+ ... when != rc
+ }
--
2.23.0