Bug#163666: debian-policy: Unclear result with and |
Hi,
On Sat, 2008-07-05 at 17:09:48 -0700, Russ Allbery wrote:
> Bug#163666 against debian-policy points out that arch-specific build
> dependencies are unclearly specified in Policy currently in the presence
> of alternatives. The current wording says:
>
> All fields that specify build-time relationships (`Build-Depends',
> `Build-Depends-Indep', `Build-Conflicts' and `Build-Conflicts-Indep')
> may be restricted to a certain set of architectures. This is
> indicated in brackets after each individual package name and the
> optional version specification. The brackets enclose a list of
> Debian architecture names separated by whitespace. Exclamation marks
> may be prepended to each of the names. (It is not permitted for some
> names to be prepended with exclamation marks while others aren't.) If
> the current Debian host architecture is not in this list and there
> are no exclamation marks in the list, or it is in the list with a
> prepended exclamation mark, the package name and the associated
> version specification are ignored completely for the purposes of
> defining the relationships.
>
> The problem is that "ignored completely" is not well-specified in the
> presence of alternatives.
> What does dpkg actually implement? In particular, how are the following
> cases handled?
It will discard any part that's not relevant for the current
architecture, and then the left relationships checked. Your usage of
satisfied confused me a bit, as I'd expect it to also depend on the
availability of those packages on that given architecture. Anyway in
your examples:
> - Is "foo [i386] | bar" satisfied on any alpha system, or are all non-i386
> systems required to have bar?
On alpha that'd become: "bar".
> - Does "foo [i386] | bar [!i386]" work correctly (require foo on all i386
> systems and bar on all other systems)?
On i386: "foo".
On !i386: "bar".
> - Similarly, does "foo [i386] | bar [amd64] | baz [!i386 !amd64]" work
> correctly (require foo on i386, bar on amd64, and baz everywhere else)?
Yes.
> - What does "foo [i386] | bar [amd64]" mean on a powerpc system? Is it
> always satisfied or never satisfied?
On powerpc it should disappear, no dependency to check, so it would be
satisfied.
> - Is "foo [!i386] | bar [!amd64]" satisfied on any i386 system, or are
> i386 systems required to have bar installed? Does this reduce to "foo |
> bar" on powerpc systems or to something else?
On i386: "bar".
On amd64: "foo".
On the rest: "foo | bar".
> These may all be different variations of the same question or may be
> different questions depending on how this is implemented internally. If
> you have any ideas as to how to word what dpkg does, they would be
> gratefully accepted.
I guess explaining that non-relevant dependencies are discarded makes it
easier to understand?
regards,
guillem
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