Eli Zaretskii <eliz@gnu.org> writes:

>> No, just that it will treat ":coding nil" in the same way as the absence
>> of a :coding arg (i.e. fallback on some default mechanism).
>
> IMO, it will be terribly confusing to have incompatible treatment of
> nil in this one API.

I tend to agree with Stefan, as I find no documentation about the
implication of no-conversion for ":coding nil" except in the C source
code.  Maybe we could add the exception back if it turns out to be too
confusing.

If there are no other problems, I'm going to use the attaching patch
which addressed the suggestions (thanks for that!).

Regards,
-- 
Daiki Ueno