Re: Recentish C-s M-y change

[Juri Linkov <juri@linkov.net>]

> In Emacs 27, putting something in the kill ring and then `C-s M-y' would
> yank that text to use when isearching.  This now enters a prompt instead
> where I can autocomplete over all the things in the kill ring.

This was changed according to this comment in isearch-yank-pop:

  Fall back on `isearch-yank-kill' for the benefits of people
  who are used to the old behavior of `M-y' in isearch mode.
  In future, this fallback may be changed if we ever change
  `yank-pop' to do something like the kill-ring-browser.

The future is now.

> This is good functionality, and I can use `C-s C-y' to get the old
> behaviour, but the `C-s M-y' is deeply ingrained in my muscle memory,
> and it's tripping me up all the time.  (And if it's doing that to me,
> it'll probably annoy somebody else, too.)
>
> Could we move the new `C-s M-y' functionality somewhere else and retain
> the old `C-s M-y' binding?

This has been discussed many times, and the most promising solution is
to add a single variable that will define whether the user prohibits
changing the definitions of traditional keys.  When its value is nil,
then with a new release the user gets new keybindings that are more
logical and consistent with other keybindings and new functionality.
However, when you set it to t, then you get all old keybindings untouched.