>
>>  (defun kill-buffer--possibly-save (buffer)
>> +  "Prompt user whether to kill BUFFER, possibly saving it first.
>> +
>> +This assumes the buffer is known to be modified."
>
> This prefers the description of what function does to describing its
> role.  I think it is better to do the opposite:
>
>     Ask the user to confirm killing of a modified BUFFER.
>
>   If the user confirms, optionally save BUFFER that is about to be
>   killed.

Style noted, revised patch attached.