Ihor Radchenko <yantar92@posteo.net> writes:

>> I believe it is up to the file to opt-out of compilation.
>
> That's true, but .dir-locals is a special file. So, I expected Emacs to
> treat it specially during compilation as well. To not break old,
> no-longer-maintained packages, if nothing.

I guess the counter argument would be that, if this file doesn't need to
compiled, and the error is that compilation of this file fails, then it
isn't a critical error.

>> If the file is created with add-dir-local-variable there is a boiler
>> plate header inserted which opts out:
>>
>>   ;;; Directory Local Variables            -*- no-byte-compile: t -*-
>>   ;;; For more information see (info "(emacs) Directory Variables")
>> ...
>> ...  The solution would be to add
>> the missing header to the .dir-locals.el file.
>
> I do not see any downside of adding this to .dir-locals.el file.
> Would you mind submitting a patch?

I've attached a patch.

(To be fully transparent, I have not verified that applying the patch
will prevent errors during native compilation of the ELPA package, but I
am pretty confident that the change is a correct one.)

-- 
Morgan Willcock