bug#27718: 26.0.50; (cl-typep instance-ab 'class-a) gives wrong answer when compiled

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

> Right. We need `get' to be aware of what the compiler has read, so it
> will need to have a reference to the compiler in there somewhere. We
> could name it differently and point the reference in the other
> direction, as in DEFSYM (Qalternate_plist_environment...) and have the
> byte compiler use that instead, which might be slightly more
> aesthetically pleasing. The other possibility is to introduce a
> different kind of `get' and use that in places that need to be aware
> of what the compiler has read.

> I don't see a third option.

Right, so we have 3 options, indeed:
- `get` looks up to byte-compile-plist-environment
- byte-compile manipulates `get`s overriding-plist-environment
- provide a new get-like function.

Either one is fine by me,


        Stefan