Date: Tue, 4 Feb 2020 11:06:52 +0200
From: Timo Teras <timo.teras@iki.fi>
To: Clayton Craft <clayton@craftyguy.net>
Cc: ~alpine/apk-tools@lists.alpinelinux.org
Subject: Re: supporting multiple versions of same package in single repo
Message-ID: <20200204110646.2d9f80b4@vostro>
In-Reply-To: <20200203222821.wty53efr5u2sx3gk@computer.craftyguy.net>
References: <20200203222821.wty53efr5u2sx3gk@computer.craftyguy.net>
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Hi

On Mon, 3 Feb 2020 14:28:21 -0800
Clayton Craft <clayton@craftyguy.net> wrote:

> In postmarketOS we are attempting to have 2 versions of mesa: 'mesa'
> (from upstream Alpine), and 'mesa-git' (tracks upstream mesa master
> branch).  The goal is to have both packages + their respective
> subpackages provide system mesa for an install. Only one (mesa or
> mesa-git) is expected to be installed on a single system at one time.
> When a user installs 'mesa-git', and then (for example) installs a
> package which depends on 'mesa-dev', the idea is that 'mesa-git-dev'
> would be installed instead of 'mesa-dev'. We want 2 versions of mesa
> since some devices pmos supports require a newer mesa than what is
> currently in the latest mesa stable branch.
> 
> We are having a very hard time coming up with a mesa-git APKBUILD
> that can do this. In IRC, it was mentioned that we could use a
> virtual package, and rename 'mesa' to something else, and handle
> installing either of the 2 packages in the virtual package. This
> would probably work (?) but is less than ideal since we'd have to
> keep the renamed mesa package in sync with upstream Alpine's mesa
> package.
> 
> Arch Linux seems to be able to handle this scenario without issue,
> AUR has a mesa-git package which results in mesa-git-* subpackages
> being installed at the right time (when something depends on
> mesa-dev, etc). Is apk/APKBUILD capable of supporting this, or does
> anyone have any advice/suggestions on how this goal could be achieved?

Interesting setup. I wonder if in Arch it is a feature where a global
substitution rule diverts mesa-dev to mesa-git-dev or similar.

Using purely apk dependencies, you could try the following:

1. mesa-git-dev
  provides="mesa-dev"
  provider_priority=1

  The provides tells it's good for 'mesa-dev'. Since there's no provided
  version specified it's not good for automatic install; the
  provider_priority=1 makes that happen.

  One caveat is at least that if someone depends e.g "mesa-dev>19.0", it
  would not get satisfied with the mesa-git-dev.

  OR

  provides="mesa-dev=19.2"

  To make the git act as if it was this version. You probably then want
  a smaller version than what the real mesa is so that the mesa-git-dev
  does not get preferred always.

2. mesa-git
  depends="!mesa"

  To make sure that depending on 'mesa-dev' does not prefer the real
  package and try to pull in it's dependencies.

Interesting to hear if the above works.

Timo