Hi Sean, Quoting Sean Whitton (2021-11-19 23:13:46) > Can you turn this into a patch against our git repo, please? maybe I'm looking at the wrong git repo but I didn't find out how to file a merge request. Thus attaching the git format-patch. Thanks! cheers, josch
>From dc186d400e47c9eed7dc94a2be4daa59b3fa2665 Mon Sep 17 00:00:00 2001
From: Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>
Date: Sat, 20 Nov 2021 22:50:49 +0100
Subject: [PATCH] fixup B-D alternatives footnote (closes: #999826)
---
policy/ch-relationships.rst | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/policy/ch-relationships.rst b/policy/ch-relationships.rst
index 915d00d..357a612 100644
--- a/policy/ch-relationships.rst
+++ b/policy/ch-relationships.rst
@@ -669,11 +669,20 @@ against newer versions of their build dependencies.
.. [#]
While ``Build-Depends``, ``Build-Depends-Indep`` and
``Build-Depends-Arch`` permit the use of alternative dependencies,
- these are not normally used by the Debian autobuilders. To avoid
- inconsistency between repeated builds of a package, the
- autobuilders will default to selecting the first alternative, after
- reducing any architecture-specific restrictions for the build
- architecture in question. While this may limit the usefulness of
+ those are only used for the backports suite on the Debian autobuilders.
+ On the other suites, after reducing any architecture-specific restrictions
+ for the build architecture in question, all but the first alternative are
+ discarded except if the alternative is the same package name as the first.
+ The latter exception is useful to specify version ranges like
+ ``foo (rel x) | foo (rel y)``. This is to reduce the risk of inconsistencies
+ between repeated rebuilds. For example if a source package build depends
+ on ``libcurl4-gnutls-dev | libcurl4-openssl-dev``, then during a transition
+ libcurl4-gnutls-dev might become uninstallable because apt only considers
+ the latest version of a package and then the source package would be wrongly
+ built with openssl instead of gnutls. Inconsistencies are not completely
+ avoided because virtual packages might still be provided by a different
+ real package and because alternatives are still preserved for binary package
+ dependencies. While this may limit the usefulness of
alternatives in a single release, they can still be used to provide
flexibility in building the same package across multiple
distributions or releases, where a particular dependency is met by
--
2.33.0
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