From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1Rol8f-0007jW-8m for garchives@archives.gentoo.org; Sun, 22 Jan 2012 00:18:29 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id AD21AE0AF1; Sun, 22 Jan 2012 00:18:20 +0000 (UTC) Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com [209.85.212.181]) by pigeon.gentoo.org (Postfix) with ESMTP id 69D5FE0ADB for ; Sun, 22 Jan 2012 00:17:17 +0000 (UTC) Received: by wibhr12 with SMTP id hr12so1493244wib.40 for ; Sat, 21 Jan 2012 16:17:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=date:from:to:subject:message-id:in-reply-to:references:organization :x-mailer:mime-version:content-type:content-transfer-encoding; bh=I33tUJ93rm+MEK1gCKl8jqnb3sHYSdOgd4gUjJQIva8=; b=VpDHvtbzXa1Mp6BEQ8Y1VBP4UNZ2wzGTiCYs6M1La40Xpnsbti38mDV5kqcdH+ivUG Bs+IunRP3DTYpPTi/lYLpk3Cp4GqSpRyochlkx72dPm0VvNnSwQgFKjAJPbwWSVCSU+u 1NF8PJ7w9s7WENj/BKBE/Pm0ec2SsPKhn6Cs4= Received: by 10.180.94.97 with SMTP id db1mr4952532wib.16.1327191436657; Sat, 21 Jan 2012 16:17:16 -0800 (PST) Received: from khamul.example.con (196-215-2-107.dynamic.isadsl.co.za. [196.215.2.107]) by mx.google.com with ESMTPS id n5sm5765705wiw.7.2012.01.21.16.17.14 (version=SSLv3 cipher=OTHER); Sat, 21 Jan 2012 16:17:15 -0800 (PST) Date: Sun, 22 Jan 2012 02:16:48 +0200 From: Alan McKinnon To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] Re: Portage option "--changed-use" not working? Message-ID: <20120122021648.1c740635@khamul.example.con> In-Reply-To: References: <4F1898FF.1070106@gmail.com> <4F18AFBE.4000403@gmail.com> <4F18C57A.1020701@gmail.com> <4F18DEAB.4070003@gmail.com> <4F192EC6.3030300@gmail.com> <20120120092755.5f406afe@digimed.co.uk> <4F193D39.9010908@gmail.com> <20120120120622.2aeaa2a8@digimed.co.uk> <20120120110052.40c6e448@fuchsia.remarqs.net> <20120121132645.61340cd3@khamul.example.con> Organization: Internet Solutions X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Archives-Salt: 24a65677-317c-49fe-9bb5-b46f44597031 X-Archives-Hash: c0ca0c65b7b6682ca38a4fdaa047a68d On Sat, 21 Jan 2012 15:45:25 -0800 Hilco Wijbenga wrote: > > But is this not a case where the kde eclass *explictly* set the USE > > flag off? (Disclaimer: haven't read the eclass). In that case > > portage would not know what to do when the flag goes away so the > > behaviour we saw would not really be a bug, it would be "playing > > safe" > > I do not quite follow your logic here. Whether a USE flag is forcibly > disabled, not enabled, or disabled by default, does not make any > practical difference: it is not used. So when it is then removed later > on, no rebuild is necessary. It was not used before, now it does not > even exist any more. Like I said, I haven't read the eclass and I'm not likely to either - it's no skin off my nose to waste cycles I'm not using overnight while 150 KDE packages rebuild. I simply wanted to point out that disabling something is not necessarily a zero-sum game. It is trivial to write ebuild statements along the lines of "if this flag is not set, then include support for that thing". If the flag then later goes away, that ebuild statement is redundant and not used as "not present" is a very different thing from "not set". Yes, a coder can build a system where that assumption is indeed applied throughout but I haven't seen anything in portage to indicate if it does or not. Figuring out what stuff you don't need to do is hard. Building a list of stuff you might need to do is very easy. The logic behind --changed-use falls square in the former case, and the math involved is not simple either. I don't know what portage will do about disabled flags that then go away. Personally, I would never write code that assumed a flag that was explicitly disabled must have done nothing and can therefore be discarded. > > --changed-use is intended for cases like a flag you are not using at > > all goes away. Caveat: Even then it could still break in subtle ways > > with dodgy ebuilds. Caveat emptor. > > Which is *exactly* what happened here (IIUC). The use of > kdeenablefinal has been discouraged from the start [or at least for a > very long time] so I (and presumably most people) never enabled it. > Now it has been removed. Ergo: nothing needs to be rebuilt. > > I do not think it makes sense to worry about dodgy ebuilds. If you go > down that road, you would have to rebuild *everything* every time > there is a change ... just in case. Dodgy ebuilds should be fixed, not > catered to. Dodgy ebuilds includes ebuilds that use legal syntax that was never a good idea to begin with. A classic case would be "no" USE flags that are thankfully now rare. We can't dismiss ebuilds that contain syntax that was perfectly legal a while ago. -- Alan McKinnnon alan.mckinnon@gmail.com