Hi,

current SLIME CVS's swank-sbcl.lisp, function preferred-communication-style contains an assumption that is no longer true about recent SBCLs. Since 0.8.21, usefully threaded SBCL builds don't include :sb-futex in their feature list any more. Still, Swank checks for the presence of :sb-futex on the *features* list before adding the :spawn communication-style.

I'm not entirely sure which of SBCL or SLIME needs to be fixed. Either SBCL should start including :sb-futex on its *feature* list again (or some other feature saying that threads are non-broken on this lisp build), or SLIME should stop checking for :sb-futex (which will break on SBCLs older than 0.8.21).

Here's the (proof of concept) patch to make slime choose the right communication-style for 0.8.21 or later (but not earlier. I know no practical way to find out if we're running in SBCL version >=X):

--- swank-sbcl.lisp 9 Apr 2005 07:07:00 -0000 1.129 +++ swank-sbcl.lisp 18 Apr 2005 22:27:45 -0000 @@ -42,8 +42,7 @@ ;;; TCP Server

(defimplementation preferred-communication-style () - (if (and (sb-int:featurep :sb-thread) - (sb-int:featurep :sb-futex)) + (if (and (sb-int:featurep :sb-thread)) :spawn :fd-handler))

Cheers,