It appears there is a problem with debug instrumentation. The
attached file causes a memory fault on 1.0.11 x86_64 darwin (10.5.0).
On i386 darwin, it results in an infinite busy loop. It works fine
with CMUCL, and for one person on 1.0.10 x86_64 linux.
Attached is the code to trigger the error and the stack trace I saw.
Note that to see the error, you must compile the entire file at (debug
1) (speed 0). If you change to debug 0 or speed 1, the bug goes
away. If you recompile just the function, it also goes away (due to
default optimization settings). And if you use defconstant instead of
the one instance of defparameter, it goes away. This is the original
reason I found the problem.
My workaround is to use (speed 1) during development instead of (speed