Subject: Re: bug#39233: .elc file - possibly outdated backward compatibility comments

From: Glenn Morris <[email-masked]>
Date: Fri, 24 Jan 2020 14:19:08 -0500

Stefan Monnier wrote:

> +       (format "(if (< emacs-major-version %d)\n"
> +               ;; Let's allow silently loading into Emacs-27
> +               ;; files compiled with Emacs-28.0.NN since the two can
> +               ;; be almost identical (e.g. right after cutting the
> +               ;; release branch) and people running the development
> +               ;; branch can be presumed to know that it's risky anyway.
> +               (if (zerop emacs-minor-version)
> +                   (1- emacs-major-version) emacs-major-version))
> +       (format "    (message \"BEWARE: %%S was compiled by a more recent version of Emacs (%s)\" #$))" emacs-version)
> +       "\n\n"))))

This looks like an unsuppressible warning using a non-standard format
("BEWARE"), hard-coded into the elc?

I had thought you would be doing this in lread.c, behind an option,
similar to the existing load_dangerous_libraries.

I guess the advantage (...) of your version is that it will have an
immediate effect in pre-existing Emacs versions.