bug#56683: 29.0.50; long lines fix doesn't work correctly when lines are truncated

[Gregory Heytings]

> > > Maybe optionally.  Or maybe displaying a message/warning suggesting 
> > > that.  I don't like disabling truncate-lines unconditionally in such 
> > > buffers, I prefer leaving that to the user.
> >
> > The user would still have the choice to disable the automatic disabling 
> > by setting long-line-threshold to nil.
>
> Yes, I understand.  I still don't like it very much.  But if many users 
> will complain, we might change that before Emacs 29 is released.

Do I understand correctly that it's okay to do that on the feature (and 
later master) branch, and that it will be perhaps be revisited later?

> No, I said making the type of the struct member current_x a ptrdiff_t or 
> intmax_t will affect performance.  The above doesn't propose any such 
> changes, it just enlarges the "infinity" value.  With that value, lines 
> up to (/ (expt 2 31) 20) => 107374182 (i.e. about 107 million 
> characters) per line will still display correctly with truncate-lines 
> when hscrolling is required.

Sorry, I misunderstood what you said.  Now it's much clearer, indeed. 
But still, as you say, that puts a limit at around 100 MB, which isn't 
"that much" nowadays.