treated by SLOT-BOUNDP, SLOT-VALUE, (SETF SLOT-VALUE) and
SLOT-MAKUNBOUND in the specified fashion.
+changes in sbcl-0.8.1 relative to sbcl-0.8.0:
+ * fixed bug 148: failure to inline-expand a local function left
+ garbage, confusing the compiler.
+ * fixed bugs 3cd: structure slot readers perform type check if the
+ slot can have an invalid value (i.e. it is either not initialized
+ or can be written with a less specific slot writer).
+ * bug fix: the compiler now traps array references to elements off
+ the end of an array; previously, the bounds checking in some
+ circumstances could go off-by-one.
+
planned incompatible changes in 0.8.x:
* (not done yet, but planned:) When the profiling interface settles
down, it might impact TRACE. They both encapsulate functions, and