From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x236.google.com (mail-lj1-x236.google.com [IPv6:2a00:1450:4864:20::236]) by sourceware.org (Postfix) with ESMTPS id 9EEA73858D39 for ; Wed, 15 Mar 2023 14:52:59 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 9EEA73858D39 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-lj1-x236.google.com with SMTP id l22so1639808ljc.11 for ; Wed, 15 Mar 2023 07:52:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1678891978; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=0AXonzK1fvF21K5WU76gIVzbNH0b5W8+Bms1jZUwKV4=; b=PxBUqFniGeBbhp6Ld7uBltyTfIffr2wjFmWlc/+az8GUN2PtXPFt8mAEKOHDwI+WJQ RYZHzl5QQYNoXwS+cHSGlOb/vQJIRCJEXxU7vH/3kG4ouvfD2OL8pyM4xECWJMd8mUZ/ rV26QGYrw5dxNppcOD35ps7sk5ub0p3vvEi0e39We9V3t2wPtlINBHfrgUN2aHvTYDM5 EXke8r0DCwSlJr/VOGVkuFEqlsIGt/4yk4Nl0IoLLh8ZkOV3sDwcGiEf9bly0Eqo5I50 t6etiGhn0uPkS3H/fL+MDuhch1+4cchBcctuWOUIcW+Vkt00eb7mDp+XgXWoFM+zWSQB kRlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678891978; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=0AXonzK1fvF21K5WU76gIVzbNH0b5W8+Bms1jZUwKV4=; b=MXT5hN6EeYtuCGG4p/rmxAkUv5tFHSa7yGwpnuVz+0ha36HTdYUtv2+nCQJ81ypYGE kjwk0KEq97KGTtvH+KzgO8Rve+H0k+TlwMVy9kYvsmspNIvMtKN/UmWcoyOSOdBhJtXw SAP9A0yxqnJjXYGJL3PqUqcWC8JL0A8boqqhXzGi2aUG/sqZFFyX0hMec68hWcuUibJ7 8VCgEzv2DQ9uAlhNg1H48U2drSwzd4RjmI5tJhRsOaJWFOAmZz/jOcY3a60A2lgV/OX+ hpQe2TDFzIWJRJ/udn7eMi7DePlzEXvFUvooontKPdOoFRBhqq8Tx10cZR13b2bsABvg uWKA== X-Gm-Message-State: AO0yUKWrpGYEJenREKARTnmfUAz5qpSLyRAB/XkOrDD+44zhFlQcfYXV rne9lXMiu9WrYvCO2Q//1IkzNL8S1kDxfIzU2vg= X-Google-Smtp-Source: AK7set+++/WzyJbtP+fkrIx4Hd/W42FqCF2k4Cwq8ifkpCvwnWz/gjZsMbvDJf65envaMk0Kw74N1i8y6uvnOetQUh4= X-Received: by 2002:a2e:b5d8:0:b0:295:bb34:9c2 with SMTP id g24-20020a2eb5d8000000b00295bb3409c2mr985255ljn.10.1678891977796; Wed, 15 Mar 2023 07:52:57 -0700 (PDT) MIME-Version: 1.0 References: <3d7d07cf-3276-b091-69d5-bf00b04e518d@gotplt.org> <20230217230525.10750-1-alx@kernel.org> In-Reply-To: From: Richard Biener Date: Wed, 15 Mar 2023 15:52:34 +0100 Message-ID: Subject: Re: Ping: [PATCH resend] Make -Wuse-after-free=3 the default one in -Wall To: Alejandro Colomar Cc: gcc-patches@gcc.gnu.org, Alejandro Colomar , Andreas Schwab , David Malcolm , Florian Weimer , Iker Pedrosa , Jens Gustedt , Jonathan Wakely , Mark Wielaard , Martin Uecker , Michael Kerrisk , Paul Eggert , Sam James , Siddhesh Poyarekar , Yann Droneaud Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-7.3 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Mar 15, 2023 at 3:30=E2=80=AFPM Alejandro Colomar via Gcc-patches wrote: > > Ping -Wuse-after-free=3D3 was explicitly added to cover cases with a high false-positive rate. If you want to make that the default then instead merge the equality compare case back to the =3D2 case. But as I said elsewhere I think that -Wuse-after-free is very much too trigger happy, especially with value-uses (not accessing released memory but inspecting the old pointer value). Please consider looking at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104075 and review the false positives reported. Also see my very recent patches from today trying to limit -Wuse-after-free by not diagnosing from late IL. Richard. > On 2/18/23 00:05, Alejandro Colomar wrote: > > Link: > > Link: > > Cc: Andreas Schwab > > Cc: David Malcolm > > Cc: Florian Weimer > > Cc: Iker Pedrosa > > Cc: Jens Gustedt > > Cc: Jonathan Wakely > > Cc: Mark Wielaard > > Cc: Martin Uecker > > Cc: Michael Kerrisk > > Cc: Paul Eggert > > Cc: Sam James > > Cc: Siddhesh Poyarekar > > Cc: Yann Droneaud > > Signed-off-by: Alejandro Colomar > > --- > > > > This is a resend of the same patch previously sent to gcc@. > > > > gcc/c-family/c.opt | 4 ++-- > > gcc/doc/invoke.texi | 2 +- > > 2 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt > > index c0fea56a8f5..1a3fc2c5d74 100644 > > --- a/gcc/c-family/c.opt > > +++ b/gcc/c-family/c.opt > > @@ -1411,11 +1411,11 @@ C ObjC C++ ObjC++ Joined RejectNegative UIntege= r Var(warn_unused_const_variable) > > Warn when a const variable is unused. > > > > ; Defining this option here in addition to common.opt is necessary > > -; in order for the default -Wall setting of -Wuse-after-free=3D2 to ta= ke > > +; in order for the default -Wall setting of -Wuse-after-free=3D3 to ta= ke > > ; effect. > > > > Wuse-after-free=3D > > -LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,2,0) > > +LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,3,0) > > ; in common.opt > > > > Wvariadic-macros > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > > index 7b308cd3c31..d910052ce0c 100644 > > --- a/gcc/doc/invoke.texi > > +++ b/gcc/doc/invoke.texi > > @@ -4720,7 +4720,7 @@ instead of pointers. This approach obviates need= ing to adjust the stored > > pointers after reallocation. > > @end table > > > > -@option{-Wuse-after-free=3D2} is included in @option{-Wall}. > > +@option{-Wuse-after-free=3D3} is included in @option{-Wall}. > > > > @item -Wuseless-cast @r{(C++ and Objective-C++ only)} > > @opindex Wuseless-cast > > -- > > GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5