bug#29520: peval leaves behind dangling lexical reference

[Mark H Weaver <mhw@netris.org>]

Mark H Weaver <mhw@netris.org> writes:

> Mark H Weaver <mhw@netris.org> writes:
>
>> I believe the problem is most likely in 'lift-applied-lambda' in
>> peval.scm.  When transforming:
>>
>>   (lambda args (apply (lambda ...) args)) => (lambda ...)
>>
>> it does not appear to check whether 'args' is referenced within the
>> inner lambda.

It occurs to me that there's another problem with this optimization:

  scheme@(guile-user)> ,optimize (lambda (x y . z) (apply (lambda x x) x y z))
  $1 = (lambda x x)

This optimization changes the arity of the procedure.  The original
version checks that at least 2 arguments are provided, and ensures that
at least 2 arguments are passed to the inner procedure, which the code
might depend on.  The optimization effectively removes this check.

I'll look into how to fix this.

       Mark