Bug#1136160: debian-policy: Clarify that Multi-Arch is not applicable for udebs

On 10/05/26 11:22 pm, Guillem Jover wrote:
> On Sun, 2026-05-10 at 15:39:38 +0100, Sean Whitton wrote:
>> Nilesh Patra [10/May  1:04pm +0530] wrote:
>>> diff --git a/policy/ch-controlfields.rst b/policy/ch-controlfields.rst
>>> index 69467c4..f4d5fe9 100644
>>> --- a/policy/ch-controlfields.rst
>>> +++ b/policy/ch-controlfields.rst
>>> @@ -1381,8 +1381,10 @@ A Debian installation can combine packages from multiple architectures.
>>>  The ``Multi-Arch`` field enables individual packages to declare their
>>>  support for this feature, and influences the way dependencies are
>>>  handled.  It can be declared in binary package sections of a source
>>> -package template control file and in binary package control files.  The
>>> -permitted field values are ``no`` (default), ``foreign``, ``same`` and
>>> +package template control file and in binary package control files.
>>> +``Multi-Arch`` must not be used for udebs, as these semantics are out
>>> +of scope for the Debian installer.
>>> +The permitted field values are ``no`` (default), ``foreign``, ``same`` and
>>>  ``allowed``. Their semantics are described in the following sections.
>>>
>>>  .. _s-f-Multi-Arch-no:
>>
>> Thanks.  Helmut, do you agree with using a "must not" here?

Helmut was the one who asked me on IRC to file a bug with `M-A must not be used`.

> Right, actually after having pondered a bit about this for whether to
> emit a warning, error or nothing in dpkg-gencontrol, my conclusion
> is that while I still agree this is not in scope, it should have no ill
> effect except for increasing the .udeb size, so I think a warning is
> enough (and that's what I've updated the patch to do now), and as such
> for Debian Policy a must seems indeed too strong. So I rescind my
> second for now. :)
Mh... Is a s/must/should/ fair enough for you? If so, Sean, would you just change
that before you apply this patch? Or do you want me to attach another patch?