bug#67916: 30.0.50; No lexical-binding directive warning in -pkg.el files

[Stefan Monnier]

> I'm wondering because elpa-admin.el seems to contain some compatibility
> code for Emacs 26 (elpaa--select-revision, elpaa--write-pkg-file) and
> Emacs versions <28 (elpaa--get-section, elpaa--html-build-doc).

AFAIK `elpa-admin.el` is mostly used with "Emacs from Debian stable" (in
`elpa.gnu.org`) and with the bleeding edge of Emacs, so backward
compatibility is not very important beyond Emacs-28 now.  The one you
see is what was added at the time and simply hasn't been removed (yet).

> You mean, you prefer package--unquote being a plain function?
> [ To be honest, I'm slightly inclined to add this to macroexp.el
>   instead, since it's a somewhat common operation. ]

Usually in the context of macro expansion you can use `eval` for that.
Here we don't, for (arguably bogus) "security" reasons.


        Stefan