bug#27634: 25.2.1; C-g does not quit register-read-with-preview

[Tino Calancha <tino.calancha@gmail.com>]

On Mon, 10 Jul 2017, Paul Rankin wrote:

> On Mon, 10 Jul 2017, at 04:33 PM, Tino Calancha wrote:
>> How about the following?
>>
>> @@ -164,6 +164,8 @@ register-read-with-preview
>>  		       help-chars)
>>  	    (unless (get-buffer-window buffer)
>>  	      (register-preview buffer 'show-empty)))
>> +          (when (eq (string-to-char "\C-g") last-input-event)
>> +            (keyboard-quit))
>>  	  (if (characterp last-input-event) last-input-event
>>  	    (error "Non-character input-event")))
>>        (and (timerp timer) (cancel-timer timer))
>
> I think that's more a bandaid than fixing the root of the problem, which is that the manual tells the user that register names are alphanumeric characters (and I assume 99% of users only use alphanumeric characters) but the function doesn't test for this. e.g. testing for C-g doesn't catch for ^L or ^M, etc.
Opps, you are right.
>
> If we want to be strict about it, this might work:
>
> @@ -164,8 +164,8 @@
> 		       help-chars)
> 	    (unless (get-buffer-window buffer)
> 	      (register-preview buffer 'show-empty)))
> -	  (if (characterp last-input-event) last-input-event
> -	    (error "Non-character input-event")))
> +	  (if (= (char-syntax last-input-event) 119) last-input-event
> +	    (error "Register name must be alphanumeric")))
>       (and (timerp timer) (cancel-timer timer))
>       (let ((w (get-buffer-window buffer)))
>         (and (window-live-p w) (delete-window w)))
>
> That prohibits anything except "a-zA-Z0-9", although users may want to save registers to "$" or "*".
I cannot assure that i've never used "@" or "," as a register.  Probably 
i did it several times.