bug#4917: Error: Attempt to modify read-only object

[Juri Linkov]

Starting Emacs fails with the error:

  Warning (initialization): An error occurred while loading `/home/juri/.emacs':

  error: Attempt to modify read-only object

  To ensure normal operation, you should investigate and remove the
  cause of the error in your initialization file.  Start Emacs with
  the `--debug-init' option to view a complete error backtrace.

Starting Emacs with the `--debug-init' option displays:

  Debugger entered--Lisp error: (error "Attempt to modify read-only object")
    delete(("\\`\357\273\277" . utf-8-with-signature) (("\\`BABYL OPTIONS:[     
]*-\\*-[        ]*rmail[        ]*-\\*-" . no-conversion) ("\\`\376\377" . 
utf-16be-with-signature) ("\\`\377\376" . utf-16le-with-signature) 
("\\`\357\273\277" . utf-8-with-signature) ("\\`;ELC" . emacs-mule)))
    (setq auto-coding-regexp-alist (delete (rassoc ... 
auto-coding-regexp-alist) auto-coding-regexp-alist))

The reason of this error in .emacs is the lines that remove a match
for `utf-8-with-signature' from `auto-coding-regexp-alist' that allows
to always display the BOM (Byte-order mark signature) to be able
to remove it without the need to visit files literally:

  (setq auto-coding-regexp-alist
        (delete (rassoc 'utf-8-with-signature auto-coding-regexp-alist)
                auto-coding-regexp-alist))

Before yesterday there were no problems with this.

-- 
Juri Linkov
http://www.jurta.org/emacs/