bug#10668: FFI: ‘set-pointer-finalizer!’ overrides the previous finalizer

[Andy Wingo]

On Mon 30 Jan 2012 23:31, address@hidden (Ludovic Courtès) writes:

> The ‘set-pointer-finalizer!’ procedure is harmful because it erases any
> previously set finalizer.
>
> Said finalizer could come from a guardian:
>
>    (define ptr (make-pointer 123))
>    (define g (make-guardian))
>    (g ptr)
>    (set-pointer-finalizer! ptr (dynamic-func "scm_is_pair" (dynamic-link)))
>    (set! ptr #f)
>    (gc)
>
>    (g)          ;; Should return PTR.
>    => #f

This has worked since 75ba64d6797f5857cc9885eb753126119a8c8b68.

Andy
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