Re: master d0a66f3e0e: Display a warning for some uses of nil in face attributes.

[Gregory Heytings]

> But should the newly introduced warning be called out in NEWS?

I don't think so, the nil value there was supported for compatibility with 
Emacs 20 but was not documented (and the message seems clear enough).

> Also, why not make this into a function?  Is it performance critical 
> enough to warrant using a macro?

It's not a macro for performance reasons, it's a macro because it didn't 
seem worth to me to make it a function.