Handling buffer renames while switching buffers

[Stebalien]

If a buffer is renamed after running consult-buffer, attempting to switch to it will open a new blank buffer with the original name. This is especially problematic in my EXWM setup, where previewing a buffer can change the buffer's name (e.g. previewing a slack window clears the unread messages count from the title).

Would it be possible to somehow record the original buffer name to buffer mapping?

[minad]

Buffer renaming is a well-known difficulty. The problem occurs also with Embark, when the minibuffer stays open while killing buffers, when buffers are renamed after a killing. I currently do not preview EXWM buffers, for this and various other reasons (focus issues). Unfortunately I don't have a simple solution for this problem. The current architecture relies quite strongly on the string identity of candidates. Maybe consult-buffer should first retrieve the actual buffer objects and attach them to the candidate strings, and then proceed from there. This change will then also affect Marginalia and Embark. It is certainly not a small fix.

[minad]

Okay, thanks. Let's wait for @oantolin's opinion then. I am testing with disabled Embark post hooks, keeping the minibuffer alive, and with disabled Marginalia cache:

(setq marginalia--cache-size 0
      embark-post-action-hooks nil
      embark-quit-after-action nil)

Embark needs this updated refinement functionn:

(defun embark--refine-multi-category (_type target)
  "Refine `multi-category' TARGET to its actual type."
  (or (let ((mc (get-text-property 0 'multi-category target)))
        (cond
         ((and (eq (car mc) 'buffer) (buffer-live-p (cdr mc)))
          (cons 'buffer (buffer-name (cdr mc))))
         ((stringp (cdr mc)) mc)))
      (cons 'general target)))

Marginalia needs a more robust buffer annotator, which also handles dead buffers:

(defun marginalia-annotate-buffer (cand)
  "Annotate buffer CAND with modification status, file name and major mode."
  (when-let ((buffer (get-buffer cand)))
    (if (buffer-live-p buffer)
        (marginalia--fields
         ((marginalia--buffer-status buffer))
         ((marginalia--buffer-file buffer)
          :truncate -0.5 :face 'marginalia-file-name))
      (marginalia--fields ("(dead buffer)" :face 'error)))))

[oantolin]

This code looks good to me, but there is another option we could consider: for non-string target calling the action non-interactively with the target as an argument.

[minad]

@oantolin Interesting. But ultimately this strategy would be too dangerous, since it requires that every action supports both calling conventions. Note that Embark can act on buffer-strings in switch-to-buffer and buffer-objects in consult-buffer. Therefore I think converting back to strings in Embark during refinement is the better approach for now. Given that this is the first situation where we allow non-string candidates, we probably still have to figure out the best way and we may adjust Embark in the future.

[oantolin]

Yes, this is certainly a less invasive change. Let's convert back and forth between strings then (that's what I call the Unix philosophy 😛).

[minad]

Haha, yes. Embark pretty much follows the Unix philosophy with strings for everything like in Bash or Tcl. :-P

PR is here: oantolin/embark#710

[minad]

All the patches have been merged (Consult, Marginalia, Embark). Closing.

[Stebalien]

Thank you!