bug#58158: 29.0.50; [overlay] Interval tree iteration considered harmful

[Gerd Möllmann]

Eli Zaretskii <eliz@gnu.org> writes:

>> I find it very hard to tell why this is done the way it is.  If someone
>> knowing the code can think of a reason, please speak up.
>
> I may be missing something, but it looks like the sole purpose of the
> iter_start/iter_finish dance is to ensure only one iteration per tree
> is running at any given time, and that's because the iteration uses
> some state variable(s) of which there's only one instance per tree.

BTW, It currently uses a "visited" flag in tree nodes, which is kind of
such a state, but something like that is normally not needed when
walking an rb-tree.