bug#70077: An easier way to track buffer changes

[Ihor Radchenko <yantar92@posteo.net>]

Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs@gnu.org> writes:

> The driving design was:
>
> - Try to provide enough info such that it is possible and easy to
>   maintain a copy of the buffer simply by applying the reported changes.
>   E.g. for uses such as `eglot.el` or `crdt.el`.
> - Make the API less synchronous: take care of combining small changes
>   into larger ones, and let the clients decide when they react to changes.

Before we discuss the API, may you allow me to raise one critical
concern: bug#65451.

If my reading of the patch is correct, your code is relying upon the
buffer changes arriving in the same order the changes are being made.
However, it is not always the case, as demonstrated in the linked bug
report.

I am skeptical that you can achieve the desired patch goals purely
relying upon before/after-change-functions, without reaching down to C
internals.

-- 
Ihor Radchenko // yantar92,
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