bug#19645: 25.0.50; Recent EIEIO changes broke helm: Lisp error: (cl-no-next-method helm--setup-source...

[Tassilo Horn <tsdh@gnu.org>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>>   helm-bbdb.el:22:1:Error: No next method for %S: helm--setup-source,
>>   nil, [eieio-class-tag--helm-type-file...
>
> It appears that you're calling helm--setup-source with an object of
> type helm-type-file, but the only method that matches is a ":before"
> method, so after running the before method, you get an error because
> there's no primary.
>
> IIUC the error should be `cl-no-primary-method' instead of
> `cl-no-next-method' (according to
> http://www.cliki.net/Proposed%20ANSI%20Revisions%20and%20Clarifications).
>
> From what I can tell, the older EIEIO code just silently did nothing
> in this case, treating the missing primary as a function that just
> returns nil, but I think this is a mistake.
>
> I'm not sure how to preserve the compatibility with this mistake.
> I'll see if I can come up with something, but in any case I think you
> should fix Helm by making sure there is some primary method defined in
> this case as well.

No if it's a usage error on the helm side which the older EIEIO simply
ignored, then I'd suggest not to reinstall compatibility with that older
version but with CLOS, i.e., signal `cl-no-primary-method' instead of
`cl-no-next-method'.

Oh, and I see that Thierry (the helm dev) already added primary methods
in

  https://github.com/emacs-helm/helm/commit/1eb07354f50ec26aa8be1290233696656b8dca32

So I'm closing this bug.

Bye,
Tassilo