bug#15045: Point jumps inappropriately around time of Semantic lexing

[Stefan Monnier]

>> The easiest solution is to add an optional argument `check-timers'
>> to input-pending-p, so you can preserve the exact same behavior.
> I assume you mean no-check-timers, nil being default.

No, I meant `check-timers', so the default behavior is modified, but
you can recover the previous behavior by passing an extra argument.

>> In the long run, we should try and clean up sit-for, but you may not
>> have the courage to dig into this right now.
> I'm arguing I don't need to dig into sit-for's complexity to maintain
> its current behavior. If (sit-for 0 ...) calls something like
> thread-yield which in turn calls timer_check, then all ways of calling
> sit-for would have unchanged behavior.

That's theory: there is no thread-yield right now, nor any timer-check.

> Also, what do you think are the merits of putting in the
> specpdl-walking check discussed earlier, enabled with
> --enable-checking?

I like the idea, tho I'd have to see the code first to know
whether it should depend on --enable-checking or something else.


        Stefan