And while I'm at, I've tweaked one line to use `aref` to access the final character of the filename directly, which avoids a (albeit minor) string allocation. 

On Wed, 9 Jun 2021, at 17:42, Colin Woodbury wrote:
> So be it! I've updated the patch.
> 
> Colin
> 
> On Wed, 9 Jun 2021, at 16:05, Stefan Monnier wrote:
>> > As for the naming of `set-extension`, the best I can think of as an
>> > alternative would be `with-extension` as a dual to `sans-extension`,
>> 
>> `file-name-with-extension` sounds good to me (better than `...set...`).
>> 
>> 
>>         Stefan
>> 
>> 
> 
> 
> *Attachments:*
>  * file-name-with-extension.patch