bug#67937: 30.0.50; auth-source-pass relies on epa-file being enabled

[Michael Albinus via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Arsen Arsenović <arsen@aarsen.me> writes:

> Hi Michael,

Hi Arsen,

> Michael Albinus <michael.albinus@gmx.de> writes:
>
>> Arsen Arsenović <arsen@aarsen.me> writes:
>>
>> Hi,
>>
>>>>> This happens due to the call of `epa-file-disable' mentioned in the
>>>>> initial recipe.
>>>>
>>>> IIUC, the call in question was only included in the recipe to simulate
>>>> the effect of the entry disappearing, and Arsen is still trying to
>>>> pinpoint the actual cause.
>>>
>>> Indeed.  That's a topic for a different bug report, though ;P
>>
>> Do you have a recipe for the problem w/o calling epa-disble-file?
>
> No.
>
> This patch/bug report addresses a real problem that exists independently
> of what triggered it in my case.

The problem happens when epa-file-handler is removed from
file-name-handler-alist, and no other handler responsible for *.gpg
files is active. Understood.

However, in normal use cases, nobody removes this handler. If I'm wrong,
I'd like to iunderstand those use cases.

So we must document, that auth-source-pass.el depends on such a
handler. We could also add a check, that there is such a handler, and
return either nil if it is missing, or return an error. As a first step,
we could add a note in the manual, see (info "(auth) The Unix password store")

Just implementing an alternative doesn't sound the right way. This would
also increase maintainance burden, if something changes how *.gpg files
shall be handled.

As example, remote files won't work when tramp-file-name-handler is
removed from file-name-handler-alist. It would be a strange approach to
implement a Tramp alternative in packades depending on Tramp, just in case.

> Your gut's nearly certainly right here :-)  I am still hunting for the
> cause of that issue.

Good.

> Regardless, what I said initially holds true ultimately: either epa-file
> should not be relied on, or a-s-p should ensure it is present.  I
> gravitate towards the former, as it reduces the complexity of getting a
> password-store entry.

I vote for the latter, because it simplifies overall maintainability.

> Have a lovely day!
>
> Arsen Arsenović

Best regards, Michael.