---
** The autoload.el library is now obsolete.
It is superseded by the loaddefs-gen.el library.
+++
** "loaddefs.el" generation has been reimplemented.
The various "loaddefs.el" files in the Emacs tree (which contain
information about autoloads, built-in packages and package prefixes)
used to be generated by functions in autoloads.el. These are now
generated by loaddefs-gen.el instead. This leads to functionally
equivalent "loaddef.el" files, but they do not use exactly the same
syntax, so using 'M-x update-file-autoloads' no longer works. (This
didn't work well in most files in the past, either, but it will now
signal an error in any file.)
Ref: https://git.savannah.gnu.org/cgit/emacs.git/tree/etc/NEWS?id=d6831d1b0a18882d688a842721dd1592884a06e2#n487
Fixes https://github.com/kaushalmodi/ox-hugo/issues/667.
From the NEWS file updates for Emacs 29: