Juri Linkov <juri@linkov.net> writes:

>> +(defun tmm-clear-self-insert-and-exit ()
>> +  "Clear the minibuffer content before self insert and exit."
>> +  (interactive)
>> +  (delete-region (minibuffer-prompt-end) (point-max))
>> +  (self-insert-and-exit))
>
> There is a special function 'delete-minibuffer-contents'
> like is used e.g. in 'read-char-from-minibuffer-insert-char'
> and 'y-or-n-p-insert-y'.

Thanks.  Here is a new version that uses this.