bug#25152: 25.1; Customize: errors for `restricted-sexp' in `repeat'

[npostavs]

merge 25152 15689
quit

Drew Adams <drew.adams@oracle.com> writes:

> emacs -Q
>
> (defcustom bar
>   `(ignore)
>   "..."
>   :type
>   '(repeat (restricted-sexp :match-alternatives (functionp)))
>   :group 'emacs)
>
> M-x customize-option bar
>
> 1. Click the INS button, to insert a new element in the list.
> 2. At the prompt "Lisp expression: ", hit `C-g'.
>
> Emacs erroneously inserts two new buttons INS and DEL.
> You can repeat this - click INS and you get two more such buttons.
>
> And if you click any of the DEL buttons then you get this error:
>
>  Symbol's function definition is void: nil
>
> Something is quite wrong with the handling of `C-g', it seems.
>
> This is the case also in older releases, going back to Emacs 20, at
> least.

Indeed, this seems to have already been reported a few years ago by one
Drew Adams ;)