consult-buffer doesn't work if a register contains a buffer

[fuzy112]

Steps to reproduce

1. C-x r B to store a buffer in a register
2. Run consult-buffer

Stacktrace

Debugger entered--Lisp error: (wrong-type-argument stringp #<buffer *scratch*>)
  propertize(#<buffer *scratch*> face consult-buffer)
  #f(compiled-function (val) "Describe buffer register VAL." #<bytecode 0x1ced750963bdb2d9>)((buffer . #<buffer *scratch*>))
  apply(#f(compiled-function (val) "Describe buffer register VAL." #<bytecode 0x1ced750963bdb2d9>) (buffer . #<buffer *scratch*>) nil)
  consult-register--describe((buffer . #<buffer *scratch*>))
  consult-register-format((98 buffer . #<buffer *scratch*>) completion)
  #<subr F616e6f6e796d6f75732d6c616d626461_anonymous_lambda_18>((98 buffer . #<buffer *scratch*>))
  consult-register--candidates(consult--buffer-register-p)
  #f(compiled-function () #<bytecode 0x29e6e06e3f1a>)()
  consult--multi-items(3 (:name "Buffer Register" :narrow (114 . "Register") :category buffer :state consult--buffer-state :enabled #f(compiled-function () #<bytecode -0xf0e54d3c501aa3b>) :items #f(compiled-function () #<bytecode 0x29e6e06e3f1a>)) t)
  consult--multi-collection([(:name "Buffer" :narrow 98 :category buffer :face consult-buffer :history buffer-name-history :state consult--buffer-state :default t :items #f(compiled-function () #<bytecode -0xccda45345b4908c>)) (:name "Hidden Buffer" :narrow 32 :hidden t :category buffer :face consult-buffer :history buffer-name-history :action consult--buffer-action :items #f(compiled-function () #<bytecode -0x165ce0172d804bc1>)) (:name "Modified Buffer" :narrow 42 :hidden t :category buffer :face consult-buffer :history buffer-name-history :state consult--buffer-state :items #f(compiled-function () #<bytecode -0x163e44cf766ea55f>)) (:name "Buffer Register" :narrow (114 . "Register") :category buffer :state consult--buffer-state :enabled #f(compiled-function () #<bytecode -0xf0e54d3c501aa3b>) :items #f(compiled-function () #<bytecode 0x29e6e06e3f1a>)) (:name "Bookmark" :narrow 109 :category bookmark :face consult-bookmark :history bookmark-history :items bookmark-all-names :state consult--bookmark-state) (:hidden t :narrow ((112 . "Project") (66 . "Project Buffer")) :name "Project Buffer" :narrow 98 :category buffer :face consult-buffer :history buffer-name-history :state consult--buffer-state :enabled #f(compiled-function () #<bytecode 0x29400161f5fd>) :items #f(compiled-function () #<bytecode -0xd749558a213aae0>)) (:hidden t :narrow ((112 . "Project") (82 . "Project Root")) :name "Project Root" :narrow 114 :category file :face consult-file :history file-name-history :action #f(compiled-function (root) #<bytecode -0x19350e4d0d92ec1f>) :items consult--project-known-roots)])
  consult--multi((consult--source-buffer consult--source-hidden-buffer consult--source-modified-buffer consult--source-other-buffer consult--source-recent-file consult--source-buffer-register consult--source-file-register consult--source-bookmark consult--source-project-buffer-hidden consult--source-project-recent-file-hidden consult--source-project-root-hidden) :require-match confirm-after-completion :prompt "Switch to: " :history consult--buffer-history :sort nil)
  consult-buffer()
  funcall-interactively(consult-buffer)
  command-execute(consult-buffer record)
  execute-extended-command(nil "consult-buffer" "con")
  funcall-interactively(execute-extended-command nil "consult-buffer" "con")
  command-execute(execute-extended-command)

[minad]

Thanks for the report. This issue needs an upstream bug report since according to the documentation buffer registers only contain buffer names.

• https://www.gnu.org/software/emacs/manual/html_node/elisp/Registers.html
• https://github.com/emacs-mirror/emacs/blob/d99354720be8655a58c8a09c5ae110f86ac9fb5d/lisp/register.el#L66

I think it would be better to stick to the convention of using names only since this way the buffer register will not get invalid when the buffer is killed (for non-file buffers). For file buffers a conversion to file-query would still be useful when the buffer is killed. Anyway this means that the implementation of buffer-to-register is incorrect.

• https://github.com/emacs-mirror/emacs/blob/d99354720be8655a58c8a09c5ae110f86ac9fb5d/lisp/register.el#L558

[fuzy112]

I filed a bug report to Emacs at https://debbugs.gnu.org/cgi/bugreport.cgi?bug=79243.

[Eli-Zaretskii]

The Emacs user manual on the master branch was already updated to not say that a buffer's name is recorded. I've now updated the ELisp manual as well. However, please note that your reference to the HTML docs is for the manuals that describe Emacs 30, not Emacs 31 (which is the master branch).

[minad]

All the docstrings in register.el have to be updated as well. But I think just changing the docs is not ideal, and even incorrect. It turns a bug into another bug since before storing buffer names was allowed. Maybe change the documentation such that both buffer handles and buffer names are allowed? This would be the most compliant solution.

With buffer names the register stays intact even when the buffer is killed. Otoh a buffer name register is not robust against buffer renames.

[Eli-Zaretskii]

All the docstrings in register.el have to be updated as well.

Which doc strings, specifically? The doc string of buffer-to-register seems okay to me.

(And why are we discussing these issues here, and not on the Emacs bug tracker?)

[minad]

See the links above regarding the docstrings. I responded here since you responded here, but I agree that this is not the correct place. As you see, I redirected this bug to the emacs bug tracker where it belongs.