GNU bug report logs - #24576
25.1; desktop.el does not fully preserve registers with macros

Previous Next

Full log

Message #8 received at 24576 <at> debbugs.gnu.org (full text, mbox):

From: Matthew Newton <matt <at> knosis.org>
To: 24576 <at> debbugs.gnu.org
Cc: dpaduchikh <at> gmail.com
Subject: bug#24576: 25.1;	desktop.el does not fully preserve registers with
 macros
Date: Fri, 10 May 2019 13:53:54 -0700

Apologies for reviving a stale bug but it appears to not be resolved yet.

Here is my experience with this, running my own build from a recent master:
GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin18.5.0, NS appkit-1671.40 Version 10.14.4 (Build 18E226)) of 2019-04-22

;; .emacs
(require ‘desktop)
(desktop-save-mode 1)


;; before killing Emacs
(pp register-alist)
((107 . #s(registerv ""
                     #[257 "\300\301\302\303!\"!\207"
                           [princ format "a keyboard macro:\n   %s" format-kbd-macro]
                           6 "\n\n(fn K)"]
                     kmacro-execute-from-register
                     #[257 "\300
!c\207"
                           [format-kbd-macro]
                           3 "\n\n(fn K)"])))

`M-x list-registers`
Register k contains a keyboard macro:
   C-e
Register p contains a buffer position:
    buffer t.el, position 21


;; after killing Emacs and running it again
(pp register-alist)
((107 . #s(registerv "" "Unprintable entity" kmacro-execute-from-register "Unprintable entity")))

`M-x list-registers`
Invalid function: "Unprintable entity”

;; Abbreviated stack trace
Debugger entered--Lisp error: (invalid-function "Unprintable entity")
  "Unprintable entity"("\5")
  #f(compiled-function (val verbose) #<bytecode 0x44180705>)(#s(registerv :data "\5" :print-func "Unprintable entity" :jump-func kmacro-execute-from-register :insert-func "Unprintable entity") nil)
  apply(#f(compiled-function (val verbose) #<bytecode 0x44180705>) #s(registerv :data "\5" :print-func "Unprintable entity" :jump-func kmacro-execute-from-register :insert-func "Unprintable entity") nil)
  register-val-describe(#s(registerv :data "\5" :print-func "Unprintable entity" :jump-func kmacro-execute-from-register :insert-func "Unprintable entity") nil)
  describe-register-1(107)
  list-registers()
  funcall-interactively(list-registers)
  call-interactively(list-registers record nil)
  command-execute(list-registers record)
  (closure ((externs) (initial-input) smex-ido-cache smex-initialized-p amx-cache amx-initialized info-lookup-mode t) (cmd) (setq cmd (intern cmd)) (cond ((and (boundp 'amx-initialized) amx-initialized) (amx-rank cmd)) ((and (boundp 'smex-initialized-p) smex-initialized-p) (smex-rank cmd))) (setq prefix-arg current-prefix-arg) (setq this-command cmd) (setq real-this-command cmd) (command-execute cmd 'record))("list-registers")
  #f(compiled-function (x) #<bytecode 0x1ff2b34c45a5>)("list-registers")



So there seem to be two bugs:

1. `desktop-save-mode` doesn’t serialize/deserialize keyboard macros properly (is it difficult to serialize a function object?)
2. Either :print-func and :insert-func should never be set to “Unprintable entity” or `register-val-describe` should handle the case where they are set to that value instead of a function. I’ve also seen “Unprintable entity” show up when a buffer position register points to a nonexistent buffer. Not sure how to reproduce that one.

I could probably dive deeper and see if I can fix this. But I would appreciate some thoughts from experienced Emacs devs about whether I understand the problem correctly. Any hints as to the best solution would also be great.

Cheers,
Matt

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.