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From: Bill Schottstaedt <bil@ccrma.Stanford.EDU>
Subject: GC missed a reference
Date: Mon, 26 Jan 2004 03:26:33 -0800	[thread overview]
Message-ID: <4014F969.7080409@ccrma> (raw)

Sorry about this less-than-ideal bug report, but maybe this
will make sense to someone.

In the CVS Guile, but not earlier versions (i.e. not 1.6.4 or any before that),
there is a problem with let: if you have a block with successive lets,
and these lets share a local name, you can get "GC missed a
reference":

wrong-type-arg: (- Wrong type argument in position ~A: ~S (1 #<freed cell 0x40b78e80; GC missed a reference>) #f)

The problem goes away if you rename the local variables so that there
are no shared names.  The bad case is basically:

(let ...
   (let ((var val)
         (var1 val1))
     ...)
   (let ((var val2)
         (var1 val3))
     ...)) ; in this body, you can get the GC missed a ref bug

Change the second "var1" to "var2" and the error goes
away. Unfortunately, I can't seem to find a simple case of this -- my
"regression" test is more than 42000 lines long, and it's not a
completely repeatable problem even without any changes.  It appears
that the 2nd binding needs to be the result of SCM_RETURN_NEWSMOB to
trigger this problem.



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             reply	other threads:[~2004-01-26 11:26 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-01-26 11:26 Bill Schottstaedt [this message]
  -- strict thread matches above, loose matches on Subject: below --
2004-04-25 11:09 GC missed a reference Bill Schottstaedt
2004-04-28 16:25 Bill Schottstaedt
2004-05-18 21:22 ` Marius Vollmer
2004-05-19 16:06   ` Bill Schottstaedt

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