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From: ludo@gnu.org (Ludovic Courtès)
To: bug-guile@gnu.org
Subject: Re: Segment fault when Guile displays a backtrace
Date: Tue, 10 Jul 2007 23:31:13 +0200	[thread overview]
Message-ID: <87y7holzdq.fsf@chbouib.org> (raw)
In-Reply-To: 595e78020707011913x2aaf3fc8le0bcc74b1eafcf32@mail.gmail.com

Hi,

xeos <xeos00@gmail.com> writes:

> I have found a bug on cvs guile. It has been reproduced by two users
> more too. When Guile crashed when it evaluates a wrong expression of
> the form:
>
>   (set! 'symbol value)
>
> Guile should throw (and it do throw) a exeption, Nevertheless it
> crashed in the middle of backtrace log.

This won't be fixed in 1.8.2 because it needs some more thought.

Basically, this has to do with memoization of the generalized `set!'.
The `(quote symbol)' is being weirdly memoized:

  $ guile -c "(set! 'x 2)"
  ERROR: In procedure memoization:
  ERROR: Bad variable (#@begin #-1#) in expression (set! (#@begin #-1#) 2).

As you can see, the memoized thing is a recursive list, hence the
endless recursion while unmemoizing the faulty expression to display the
backtrace.

The real fix may be to remove the `macroexp ()' function, as already
suggested by the comment in there.  Thus I'll look at it after 1.8.2 is
out (if no one fixes it in the meantime  ;-)).

Thanks,
Ludovic.



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  reply	other threads:[~2007-07-10 21:31 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-02  2:13 Segment fault when Guile displays a backtrace xeos
2007-07-10 21:31 ` Ludovic Courtès [this message]
2007-07-24 23:25 ` Ludovic Courtès
  -- strict thread matches above, loose matches on Subject: below --
2007-07-02 13:15 Marco Maggi

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