bug#67005: 30.0.50; improve nadivce/comp/trampoline handling

[Stefan Monnier]

> What about this one?  Too indiscrete?
>
>   (when purify-flag
>     (message "\a\nWarning: Invalid pre-dump advice on %s\n" symbol))

That works.

> Plus another idea: Instead of placing the test into `advice-add', how
> about checking functions for advices in loadup.el?  We could place that
> check just before site-load.el gets loaded, to avoid trouble for Emacs
> modders.  I tried the following, and it seemed to do the trick:
>
> +(mapatoms
> + (lambda (f)
> +   (and (advice--p (symbol-function f))
> +        (error "Pre-dump advice on %s" f))))

Even better!


        Stefan