Bug#1020851: elpa-ement: fails to install along emacs

[Sean Whitton <spwhitton@spwhitton.name>]

Hello,

On Wed 23 Nov 2022 at 01:17PM +01, Andreas Beckmann wrote:

> On 23/11/2022 01.11, Sean Whitton wrote:
>> Hello,
>> On Tue 22 Nov 2022 at 05:39PM +01, Andreas Beckmann wrote:
>>
>>> On 28/09/2022 16.55, Sean Whitton wrote:
>>>> transient is included in Emacs 28 so I'm inclined to leave this to fix
>>>> itself when Emacs 28 migrates.
>>>
>>> Can't this be expressed as a package relationship?
>>> e.g. Depends: emacs-el (>= 1:28)
>> It's against the Emacsen Team policy to have a hard dependency on Emacs
>> -- instead, it's in Recommends.  So I'd prefer not to add a dependency
>> that I'm only going to have to remove in a few weeks when Emacs
>> migrates.  But if you think this bug is getting in the way then I can
>> add it.
>
> There is another occurrence of this bug in elpa-snakemake, #1024648.
> Diane made me aware that there is currently a elpa-transient package ...
>
> Quoting myself what I wrote there:
>
>> But if emacs-el (or -common?) bundles extensions (or however you call them),
>> especially ones that were previously packaged separately, it should probably
>> have versioned Provides (and maybe versioned Breaks, too) for
>> them. (Cf. perl, perl-base which does the same.)
>> Not sure whether these should be in -el or -common ...
>> If these Provides were available, elpa-snakemake wouldn't need to know about
>> the packaging details of other packages and could just use
>>   Depends: elpa-transient
>
> There are a few other packages currently using Depends: elpa-transient

elpa-transient isn't a transitional package -- we'll keep it in Debian
even after Emacs 28 is the only Emacs we have.  This is because we might
need a newer version of transient available for another package.

So far our strategy has been to handle this in the code in dh_elpa that
generates dependencies, and also not worry about it too much, unless we
get a combination that results in something not having its dependency
available.

I don't think we should be adding Provides/Breaks anywhere without
considering corresponding changes in dh_elpa.

-- 
Sean Whitton