bug#46906: 28.0.50; byte compiler infloops trying to compile infloop

[Pip Cet <pipcet@gmail.com>]

On Thu, Mar 4, 2021 at 11:16 AM Lars Ingebrigtsen <larsi@gnus.org> wrote:
> Pip Cet <pipcet@gmail.com> writes:
> > I don't think so, because it doesn't work for Lisp infloops.
> > (with-timeout (1 (error "foo")) (while t)) doesn't work here, at
> > least.
>
> Yes, you need to put something that yields in there for `with-timeout'
> to work.  For instance:
>
> (with-timeout (1 (error "foo")) (while t (sleep-for 0.1)))
>
> However, I haven't checked whether this form triggers the bug that we're
> trying to reproduce.

Even if it would, that wouldn't solve our issue: it's the optimizer
which infloops trying to compile the form, and the optimizer certainly
does not yield anywhere that I'm aware of...

I think we're just going to have to put in a test which, on systems
with the bug, loops indefinitely. We could make it "expensive", though
it isn't, really.

(I'm not sure how many people are trying to run the Emacs 28 testsuite
against Emacs 27, or anything like that. It might be a non-issue.)

Pip