From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dedi548.your-server.de (dedi548.your-server.de [85.10.215.148]) by sourceware.org (Postfix) with ESMTPS id 0D8B338582BA for ; Fri, 8 Jul 2022 13:39:50 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0D8B338582BA Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=embedded-brains.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=embedded-brains.de Received: from sslproxy01.your-server.de ([78.46.139.224]) by dedi548.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1o9oCw-000Alq-FF; Fri, 08 Jul 2022 15:39:46 +0200 Received: from [82.100.198.138] (helo=mail.embedded-brains.de) by sslproxy01.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1o9oCw-000Nf0-LM; Fri, 08 Jul 2022 15:39:46 +0200 Received: from localhost (localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id 599BA48013F; Fri, 8 Jul 2022 15:39:46 +0200 (CEST) Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 89WtrmA2WM77; Fri, 8 Jul 2022 15:39:46 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id 0F4DA480187; Fri, 8 Jul 2022 15:39:46 +0200 (CEST) X-Virus-Scanned: amavisd-new at zimbra.eb.localhost Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id CIe2xPNqqmVe; Fri, 8 Jul 2022 15:39:45 +0200 (CEST) Received: from [192.168.96.159] (unknown [192.168.96.159]) by mail.embedded-brains.de (Postfix) with ESMTPSA id E0D9448013F; Fri, 8 Jul 2022 15:39:45 +0200 (CEST) Message-ID: <5be9cc5f-7346-0f27-20dc-c51534b7e93f@embedded-brains.de> Date: Fri, 8 Jul 2022 15:39:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH] Introduce hardbool attribute for C Content-Language: en-US To: Richard Biener , Alexandre Oliva Cc: GCC Patches References: From: Sebastian Huber In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Authenticated-Sender: smtp-embedded@poldinet.de X-Virus-Scanned: Clear (ClamAV 0.103.6/26596/Thu Jul 7 09:53:54 2022) X-Spam-Status: No, score=-5.4 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, NICE_REPLY_A, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 08 Jul 2022 13:39:52 -0000 On 08.07.22 08:58, Richard Biener via Gcc-patches wrote: > On Thu, Jul 7, 2022 at 10:00 PM Alexandre Oliva via Gcc-patches > wrote: >> >> This patch introduces hardened booleans in C. The hardbool attribute, >> when attached to an integral type, turns it into an enumerate type >> with boolean semantics, using the named or implied constants as >> representations for false and true. >> >> Expressions of such types decay to _Bool, trapping if the value is >> neither true nor false, and _Bool can convert implicitly back to them. >> Other conversions go through _Bool first. >> >> Regstrapped on x86_64-linux-gnu. Ok to install? > Does this follow some other compilers / language? Is such feature used > in existing code? Why is it useful to allow arbitrary values for true/= false? > Why is the default 0 and ~0 rather than 0 and 1 as for _Bool? Maybe this helps to catch errors caused by radiation which resulted in a=20 bit flip in a processor register or other memory. If you use a single=20 bit for true/false you can't detect such an error without special hardwar= e. --=20 embedded brains GmbH Herr Sebastian HUBER Dornierstr. 4 82178 Puchheim Germany email: sebastian.huber@embedded-brains.de phone: +49-89-18 94 741 - 16 fax: +49-89-18 94 741 - 08 Registergericht: Amtsgericht M=C3=BCnchen Registernummer: HRB 157899 Vertretungsberechtigte Gesch=C3=A4ftsf=C3=BChrer: Peter Rasmussen, Thomas= D=C3=B6rfler Unsere Datenschutzerkl=C3=A4rung finden Sie hier: https://embedded-brains.de/datenschutzerklaerung/