Re: eval-when-compile help?

[Dmitry Gutov]

On 05.10.2021 15:19, Stefan Monnier wrote:
> > +(when (version< emacs-version "28")
> > +  (eval-and-compile
> > +    (require 'eieio)
> > +
> > +    (defclass xref-location () ()
> > +      :documentation "(Obsolete) location represents a position in a file or 
> > buffer.")))
> [...]
> > Am I overdoing it with 'eval-and-compile'?
>
> I suspect that "from the outside" you don't need the `eval-and-compile`
> at all here.  But if you remove it, there's a good chance that
> compilation of `defclass` will fail (because the `require` won't be
> executed at compile-time).
> This said, I'd recommend you hoist the `eval-and-compile` outside of the
> `when` so that `eieio` is not loaded in Emacs≥28.

In my testing, this doesn't make `eieio` loaded in Emacs 28 at runtime. 
Though I suppose it gets loaded during byte-compilation.

Moving `eval-and-compile` to the top level makes a lot of sense, but now 
I get the compilation warnings back (when compiling in Emacs 28).

So I suppose this is the final form:

(eval-and-compile
  (when (version< emacs-version "28")
    (require 'eieio)

    (with-no-warnings
      (defclass xref-location () ()
        :documentation "(Obsolete) location represents a position in a 
file or buffer."))))