Subject: Re: bug#30626: 26.0.91; Crash when traversing a `stream-of-directory-files'

From: Eli Zaretskii <[email-masked]>
Date: Wed, 28 Feb 2018 18:00:00 +0200

> From: Michael Heerdegen <[email-masked]>
> Cc: Eli Zaretskii <[email-masked]>,  [email-masked]
> Date: Wed, 28 Feb 2018 11:58:49 +0100
> 
> >     (FIRST-VALUE . FUNCTION-TO-PRODUCE-REST-OF-LIST)
> 
> Yes, that's exactly how it's implemented.  When requesting more elements
> from the stream, that becomes
> 
>       (FIRST-VALUE .
>         (SECOND-VALUE . FUNCTION-TO-PRODUCE-MORE-REST-OF-LIST))
> 
> When we loop over the string, the cons whose car is the FIRST-VALUE,
> let's call it cons1, is immediately thrown away, and we continue with
> 
>       (SECOND-VALUE . FUNCTION-TO-PRODUCE-MORE-REST-OF-LIST)
> 
> etc.

How do you see that the car is immediately thrown away?

> AFAIU the problem is that the cons1 still exists in memory until garbage
> collection kicks in.  When that happens, the cons1 points to a largely
> recursive cons structure, though this structure is never referenced from
> Lisp in this form.

What is "cons1" in this context?