Bug report:
Running Stefano's Sudoku example from his cells-doc in Lispworks for
Linux 5.1, got an error in record-caller:
Error: The subscript 16 exceeds the limit 15 for the first dimension
of the array #*1111111111111111.
1 (abort) Return to level 0.
2 Return to top loop level 0.
Lispworks said the offending code was at the indicated line:
(handler-case
(setf (sbit (cd-usage *depender*) used-pos) 1) ; <== ### here ###
(type-error (error)
(declare (ignorable error))
(setf (cd-usage *depender*)
(adjust-array (cd-usage *depender*) (+ used-pos 16) :initial-element 0))
(setf (sbit (cd-usage *depender*) used-pos) 1))))
Fix:
The condition reported was of type CONDITIONS:SUBSCRIPT-OUT-OF-BOUNDS.
I added that to the handler-case, and then it worked:
(handler-case
(setf (sbit (cd-usage *depender*) used-pos) 1)
((or type-error conditions:subscript-out-of-bounds) (error)
;^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(declare (ignorable error))
(setf (cd-usage *depender*)
(adjust-array (cd-usage *depender*) (+ used-pos 16) :initial-element 0))
(setf (sbit (cd-usage *depender*) used-pos) 1))))
However, this seems like a demonstrably error-prone way to handle this
particular situation, so I got rid of the handler-case entirely and
tried this:
(let ((cd-usage (cd-usage *depender*)))
(when (>= used-pos (array-dimension cd-usage 0))
(setf cd-usage
(setf (cd-usage *depender*)
(adjust-array (cd-usage *depender*)
(+ used-pos 16)
:initial-element 0))))
(setf (sbit cd-usage used-pos) 1))
It works, doesn't depend on implementation-specific conditions, and in
my limited testing (I ran the sudoku solver three times using each
version), seems at least as fast, if not a tiny bit faster.
-- Larry
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