From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E97FC43461 for ; Sat, 5 Sep 2020 17:58:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5238520760 for ; Sat, 5 Sep 2020 17:58:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728465AbgIER6f (ORCPT ); Sat, 5 Sep 2020 13:58:35 -0400 Received: from smtprelay0111.hostedemail.com ([216.40.44.111]:36470 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728387AbgIER6d (ORCPT ); Sat, 5 Sep 2020 13:58:33 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay02.hostedemail.com (Postfix) with ESMTP id 1EF071E01; Sat, 5 Sep 2020 17:58:32 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: earth46_3514226270bc X-Filterd-Recvd-Size: 2360 Received: from XPS-9350.home (unknown [47.151.133.149]) (Authenticated sender: joe@perches.com) by omf07.hostedemail.com (Postfix) with ESMTPA; Sat, 5 Sep 2020 17:58:30 +0000 (UTC) Message-ID: Subject: [PATCH] checkpatch: Warn on self-assignments From: Joe Perches To: Andrew Morton Cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org, Kees Cook , "Gustavo A . R . Silva" , Denis Efremov , julia.lawall@inria.fr Date: Sat, 05 Sep 2020 10:58:29 -0700 In-Reply-To: <20200901094812.428896-1-efremov@linux.com> References: <20200811210127.11889-1-efremov@linux.com> <20200901094812.428896-1-efremov@linux.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The uninitialized_var() macro was removed recently via commit 63a0895d960a ("compiler: Remove uninitialized_var() macro") as it's not a particularly useful warning and its use can "paper over real bugs". Add a checkpatch test to warn on self-assignments as a means to avoid compiler warnings and as a back-door mechanism to reproduce the old uninitialized_var macro behavior. Signed-off-by: Joe Perches --- scripts/checkpatch.pl | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 149518d2a6a7..300b2659aab3 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -3901,6 +3901,17 @@ sub process { #ignore lines not being added next if ($line =~ /^[^\+]/); +# check for self assigments used to avoid compiler warnings +# e.g.: int foo = foo, *bar = NULL; +# struct foo bar = *(&(bar)); + if ($line =~ /^\+\s*(?:$Declare)?([A-Za-z_][A-Za-z\d_]*)\s*=/) { + my $var = $1; + if ($line =~ /^\+\s*(?:$Declare)?$var\s*=\s*(?:$var|\*\s*\(?\s*&\s*\(?\s*$var\s*\)?\s*\)?)\s*[;,]/) { + WARN("SELF_ASSIGNMENT", + "Do not use self-assignments to avoid compiler warnings\n" . $herecurr); + } + } + # check for dereferences that span multiple lines if ($prevline =~ /^\+.*$Lval\s*(?:\.|->)\s*$/ && $line =~ /^\+\s*(?!\#\s*(?!define\s+|if))\s*$Lval/) {