bug#70784: Abolish string resizing

[Mattias Engdegård]

5 maj 2024 kl. 16.04 skrev Eli Zaretskii <eliz@gnu.org>:

> How many places in our own sources call aset on strings?

In general, very little. Resizing ones, probably none now.

> I'm not yet sure this is a good idea, but one thing I'm sure: it is
> not for Emacs 30.  So if we decide to go this way, let's delay
> merging the changes until after the emacs-30 branch is cut, which
> should happen in a week or two.

That's fine, but a warning might help in emacs-30 to prepare for making 
resizing an error in emacs-31.
Here's how that would work: the first 5 times (say), emit a warning like

 Warning: `aset' on a multibyte string with char value #x2022 will become an 
error in Emacs 31

followed by a truncated stack trace, just enough to help the user (or someone 
helping out) see what package is responsible.