On Thu, 05 Jan 2006 13:10:59 -0600, Stephen Compall s11@member.fsf.org said:
Stephen> A brief discussion in #lisp pointed me to the EXIT-EXTENT:MINIMAL ANSI Stephen> issue[1]. The salient point is that there is no way to portably stop Stephen> all unwinding for a non-local exit at a particular point, due to this Stephen> case of undefined behavior:
Stephen> ;;returns 2 under MEDIUM, is error under MINIMAL Stephen> (block a Stephen> (block b Stephen> (unwind-protect (return-from a 1) Stephen> (return-from b 2))))
Stephen> A CL implementation that implements MEDIUM should still be fully Stephen> compliant with the MINIMAL decision. Therefore, I would like to hear Stephen> from those with particular interest in any particular implementation Stephen> running CFFI: does implementation X implement EXIT-EXTENT:MEDIUM, and/or Stephen> does its callback definition form as exploited by cffi-sys:%defcallback Stephen> have some "magic" unwind stopping?
LispWorks implements MEDIUM.