bug#41531: 28.0.50; proper Eldoc async support

["João Távora" <joaotavora@gmail.com>]

Theodor Thornhill <theothornhill@pm.me> writes:

> Bug 1:      
> 1. Open a file
> 2. Start eglot
> 3. Hover something with "C-h ."
> 4. Switch to the new window that popped up.
> 5. C-x k (kill buffer)
> 6. Repeat step 3.
> 7. "invalid buffer" and eldoc is dead. 
> 8. Starting and stopping eldoc doesn't work   
>
> This seems to happen since it uses the new buffer and updates it. When that buffer is deleted, it gets confused.

Thanks.  This is easy to fix.  It's a buffer-live-p call somewhere.

> Bug 2:
> 1. (setq eldoc-echo-area-use-multiline-p nil)
> 2. eglot spits the whole thing on one line. This looks a bit weird since it uses both the signature and the documentation.
>
> This may not be a bug, but right now IMO it looks a bit strange.

It was intended.  But I agree it's not good.  I will change it: instead
of joining all lines, then trucating, I will just truncate the first
line if needed.

> Bug 3:
> 1. "M-:"
> 2. Type "("
> 3. Minibuffer shows: eldoc-error: (wrong number of arguments (0 . 0) 1)

I couldn't reproduce this one.

> I think the first bug is the most problematic one though :)
>
> However, I've started to take a liking to the no options set, with
> this version. I think I like the "truncate, press M-x ..." message
> more than the previous one.

Yes, and if `eldoc-doc-buffer` is bound to something shorter, then it
will be even simpler to read.  I will eventually recommend we rebind
`C-h .` (display-local-help) to it.  But in the meantime, I think I will
make Eglot bind it to that key, as an exception to Eglot's
no-keybindings policy.

João