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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3ADCC433EF for ; Fri, 1 Jul 2022 23:14:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230009AbiGAXOv (ORCPT ); Fri, 1 Jul 2022 19:14:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229496AbiGAXOv (ORCPT ); Fri, 1 Jul 2022 19:14:51 -0400 Received: from sdaoden.eu (sdaoden.eu [217.144.132.164]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17C585A2DD for ; Fri, 1 Jul 2022 16:14:49 -0700 (PDT) Received: from kent.sdaoden.eu (kent.sdaoden.eu [192.0.2.2]) by sdaoden.eu (Postfix) with ESMTPS id 6B5F616059; Sat, 2 Jul 2022 01:14:46 +0200 (CEST) Received: by kent.sdaoden.eu (Postfix, from userid 1000) id EA1058E23F; Sat, 2 Jul 2022 01:14:39 +0200 (CEST) Date: Sat, 02 Jul 2022 01:14:39 +0200 Author: Steffen Nurpmeso From: Steffen Nurpmeso To: DASH shell mailing list Cc: Robert Elz Subject: $(()) pre/postfix bug Message-ID: <20220701231439.egWzS%steffen@sdaoden.eu> User-Agent: s-nail v14.9.24-259-ge9cf982228 OpenPGP: id=EE19E1C1F2F7054F8D3954D8308964B51883A0DD; url=https://ftp.sdaoden.eu/steffen.asc; preference=signencrypt BlahBlahBlah: Any stupid boy can crush a beetle. But all the professors in the world can make no bugs. Precedence: bulk List-ID: X-Mailing-List: dash@vger.kernel.org Hello. I am currently writing a $(()) expression parser, using Dijkstra's two stack algorithm (heavily impressed by the busybox one). While doing so i encountered diverging behaviour in between shells, and a bug in dash (and a memory failure in NetBSD 9 ksh). For my own thing i hope i end up like bash (that is: just do it (tm)), but the NetBSD and OpenBSD variants i also like, as they mimic C and give an understandable error message. I Cc: some of you, just for your interest. Ciao. == Name: dash Path: /usr/ports/core Version: 0.5.11.5 #?2|kent:$ dash -c '(i=10; echo $((++-+++i)))' -10 #?2|kent:$ dash -c '(i=10; echo $((+++++i)))' 10 #?0|kent:vm$ dash -c '(i=10; echo $((+ + + ++i)))' 10 == GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu) #?0|kent:$ bash -c '(i=10; echo $((++-+++i)))' -11 == BusyBox v1.34.0 (2022-01-03 21:34:20 CET) multi-call binary. #?0|kent:$ busybox.static sh -c '(i=10; echo $((++-+++i)))' sh: arithmetic syntax error #?0|kent:$ busybox.static sh -c '(i=10; echo $((+ + - + ++i)))' -11 == FreeBSD 13.1-RELEASE releng/13.1-n250148-fc952ac2212 GENERIC FreeBSD 13.1 #|f-1301-x86:~$ sh -c '(i=10; echo $((++-+++i)))' sh: arithmetic expression: expecting primary: "++-+++i" == OpenBSD 7.1 (GENERIC.MP) #465: Mon Apr 11 18:03:57 MDT 2022 #?1|o-0701:steffen$ ksh -c '(i=10; echo $((++-+++i)))' ksh: ++-+++i: ++ requires lvalue #?1|o-0701:steffen$ ksh -c '(i=10; echo $((+++i)))' ksh: +++i: ++ requires lvalue #?1|o-0701:steffen$ ksh -c '(i=10; echo $((++i)))' 11 #?0|o-0701:steffen$ ksh -c '(i=10; echo $((+ + + ++i)))' 11 #?0|o-0701:steffen$ ksh -c '(i=10; echo $((+ + - + ++i)))' -11 == NetBSD n-0900 9.0 NetBSD 9.0 (GENERIC) #0: Fri Feb 14 00:06:28 UTC 2020 mkrepro@mkrepro.NetBSD.org:/usr/src/sys/arch/amd64/compile/GENERIC amd64 #?0|n-0900:steffen$ ksh -c '(i=10; echo $((++-+++i)))' Memory fault #?2|n-0900:steffen$ sh -c '(i=10; echo $((+++++i)))' sh: arithmetic expression: incr/decr require var name: "+++++i" #?2|n-0900:steffen$ sh -c '(i=10; echo $((+ ++i)))' 11 #?0|n-0900:steffen$ sh -c '(i=10; echo $((+ - ++i)))' -11 --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)