From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com [209.85.128.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00ADB2E2847 for ; Mon, 22 Sep 2025 19:34:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758569660; cv=none; b=GOsmzGjIrRHB369jTAC9qB+Ph9E8Xh0mITV3fXXTPMNBZyJZyal0rd/p9yninvBuyUP0bVgPd3HLGxeiKCIc9tRK9Pqv9+sKvflUtGq6azqBKNkD2bS56dCdlrFSKwhDyI4BN6iuls0Ps5BTYPgEYNTwPgtFbuJvl3Uoi8KX4xY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758569660; c=relaxed/simple; bh=PW2gMztpS8JzGRvGTyQaw2gaFmkEBDfr64xUGDW5VdU=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HCi/FysH1gpDktGVV4wcK2KTNL0mnaDeC5SM0QFBieRgW5gZ2mzCB23M0eN7++Br2ZRl2MAwkNh3HVER4LbPoWBNU6IvC4iBkn/rFIL11NRuM97n2Saiznv22U8zdJHIEP25F9m6V4o8rY2UX2A8QGW9YpRR8VS80ZH657MNLbA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=e9SbkBcX; arc=none smtp.client-ip=209.85.128.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="e9SbkBcX" Received: by mail-wm1-f50.google.com with SMTP id 5b1f17b1804b1-46cbdf513d7so16782845e9.2 for ; Mon, 22 Sep 2025 12:34:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1758569657; x=1759174457; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:to:from:date:from:to:cc :subject:date:message-id:reply-to; bh=YHBp3yioTXfT4ICKdIqCJ4uLrUndIsGPmcSZJnvVKQ8=; b=e9SbkBcXOHmQGTTRgLBG07PAiYn/BLW31UET4gtjVpKuzjHvyYBxY3KCz9DRsZuXKZ 1tGjgoLIgN2/S2qvRO3MKcgyR50XTlIrXo56PIIYWFcX0gAhmxxqMZBqK7HbC775uH95 hFCP8F1ZT0ROIhvVtUeRHjWoQwkmGPfy0NukbcBqCdQvkMoulrWKAUmppM12/O925OhX X5qHZ96rfwbnhU0YAxa/FesKL2B9l/+JqPmLqBAAQDh3BxtVymA6jg163ahulsOKXYvA 8lDY6O4YxqzSje7kGhOX56X5ZjX+NZiwskFdXugyQl96gsCvgA7/I7X/xttHbVqUtMqu NB/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758569657; x=1759174457; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=YHBp3yioTXfT4ICKdIqCJ4uLrUndIsGPmcSZJnvVKQ8=; b=Sz3yVHq3ac9NcZgocj/RfsoIX5bbsqJqzngt2Soqr+VL1VVqtBJ43sE0sbtKDtCg8B WFdr5Mm1YzJ4ms/LhlhNUyps8f3fA/jNFFO8DD6ID/jJx5eFeTO28A/QCKUTGykzmKak EDKrCwZ4LV0pRc7F6gCqMARtr/+ICTGiMpPZuAkJvC+sjv3ulxCAMp1CZE/s3FDJId74 m4luNEN69Ns1BGZHdg2k4MQtlAeXNt51MiKYOAhGqoDchMQjbLBaiBi4CHBaJjhHFj4S a4USxdNfoy2gIb014sENJLe0bG7lGrolanWxRI1S4vbsIbWV93aw0yD31bytRbJQ7agW Q05Q== X-Forwarded-Encrypted: i=1; AJvYcCUIeQKxCoz/SeogiUm5OWbWgc4nowhEWjCLA4l8PwjtSL5zXVTNqdda5Pr88BhOj7Kjock=@vger.kernel.org X-Gm-Message-State: AOJu0YyrAa7YN1rtcHN6tsu90h5tgJ6NnhPMe0EK52sm0b71W98JrtiD KF16QWr6Qd+t42cNnE740h3sxNEzdUTPAsiUUMcuJsseGeItaoDYF1Ly X-Gm-Gg: ASbGncsgxqu1zyydInRg02w1xehaOkGsVqNwA2HOJzsqEOrLuz3lvWp9Qni9MuSXIV9 4ywyKF11Cco29mpmBQ31RMmRCP13yb6/LZ3tjoe+KpKUp84AY94xjQ2eFMPrwnhcTDTAocgkp+r t+ohxDDXTTdJUs2e6iWG+Ds/njilp6zlmK6YPccerznNWixeSezrU0M34XtrQ2zaGRJB4RLxpol Y8p56q9Ywc1tBfD+rUfC5Z9AMrvQnctzQ52+Xsx4s6BcqiAinxTuM8MZxsYpWzAArnSw8o0lwiD oa1RQBllPuHLOh2/Kvhz+h2+817vcwdE3NWGh581H8+goCF/VfyKo7HkTf2N63uQ0DV+juwRQzD /h7ZSkbAXzwZm2ztFUNfyDRbE2ypgUDdiA/+f3d67gETjGN6tPa5B3tA= X-Google-Smtp-Source: AGHT+IFZNkG2ttfMIvNauKBrIyuhjBOnY8ebcn5PUHT21k/rxVh1COQljr9leUbeoTvYF1k7s2wNww== X-Received: by 2002:a05:6000:230e:b0:3ed:e1d8:bd6f with SMTP id ffacd0b85a97d-3ee86b84781mr11121927f8f.60.1758569656895; Mon, 22 Sep 2025 12:34:16 -0700 (PDT) Received: from localhost (84-236-109-231.pool.digikabel.hu. [84.236.109.231]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-461383b7b9csm256523765e9.2.2025.09.22.12.34.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Sep 2025 12:34:16 -0700 (PDT) Date: Mon, 22 Sep 2025 21:34:15 +0200 From: SZEDER =?utf-8?B?R8OhYm9y?= To: "brian m. carlson" , Patrick Steinhardt , git@vger.kernel.org, "Haelwenn (lanodan) Monnier" , Ben Knoble , Christian Brabandt , Collin Funk , Eli Schwartz , Elijah Newren , Ezekiel Newren , Johannes Schindelin , Junio C Hamano , Phillip Wood , Pierre-Emmanuel Patry , Sam James , Taylor Blau , Kristoffer Haugsbakk Subject: Re: [PATCH v5 7/9] BreakingChanges: announce Rust becoming mandatory Message-ID: References: <20250915-b4-pks-rust-breaking-change-v5-0-dc3a32fbb216@pks.im> <20250915-b4-pks-rust-breaking-change-v5-7-dc3a32fbb216@pks.im> Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Sep 18, 2025 at 01:19:19AM +0000, brian m. carlson wrote: > On 2025-09-17 at 22:09:10, SZEDER Gábor wrote: > > Providing an LTS release for those platforms that can't jump on the > > Rust bandwagon is great, but... > > > > Git 3.0 will switch the default hash algorithm for newly initialized > > repositories to SHA-256, which, presumably, will also encourage SHA-1 > > -> SHA-256 migrations in existing repositories. Alas, it appears that > > the SHA-1/SHA-256 interop feature will only be available in Rust. > > > > How will this affect those platforms without Rust? What will and > > won't work on such platforms? > > On Git 3.0, nothing will work without Rust because it will be mandatory. Well, "What will and won't work with respect to hash transition" was what I meant but, alas, didn't convey. > However, people who want to perform the conversion can do that by > booting a Linux VM[0] and converting the repository there, then pushing > it somewhere. The only inconvenience is that you'll have to have a flag > day for working with the repository on older Git: you won't be able to > dynamically pull from or push to a repository with a different main > algorithm than you. > > One of my first patches is that setting extensions.compatObjectFormat > without Rust will simply die and say that's not supported. If that > config value is unset, then Git up to 3.0 will simply function as > normal, so full single-hash compatibility is assured. We already have > that: SHA-256 repositories work just fine with SHA-256 remotes and SHA-1 > repositories work just fine with SHA-1 remotes, but they're currently > not interoperable. Thanks for the explanation. I think this would indeed be a worthwhile addition to the commit message, or perhaps even to the BreakingChanges document. > > I think it should be called out explicitly in the justification that > > whatever limitations this imposes on those platforms with respect to > > hash function transition, the project has duly considered that and is > > OK with it. > > I am fine with this and I don't think this is a problem. Not sure I can agree with that, though. > I realize the decision to incorporate Rust was made recently, Indeed it was.