bug#57804: An infinite loop in a `fontify-region' function causes Emacs to hang indefinitely

[Gregory Heytings]

> Is it technically impossible to lift narrowing restrictions in Emacs 29

It is not, you can choose a radical approach and long-line-threshold to 
nil.  Or you can choose a less radical approach and set 
long-line-threshold to a larger value (as I already told you twice IIRC).

> (as in, something would break),

Locked narrowing is one part of the solution to the long lines bug in 
Emacs, so something could indeed break if you turn that solution off.

> or is it "you have to rewrite, because we have decided so"?

That's not how I would present things, no.  Why does Logview infloop when 
locked narrowing is in effect?  This might be a bug in Logview: 
fontification-functions / jit-lock-function is not supposed to access and 
modify a large portion of the buffer.  I don't use Logview, and you did 
not give a detailed recipe to reproduce the issue, so it's difficult to 
give more precise advice.