[Sbcl-devel] failure in debug.impure.lisp?

[William H. N. <wil...@ai...>]

Doing (LOAD (COMPILE-FILE "bug353.lisp")) on this file 
  (cl:in-package "CL-USER")
  (defun frob (x)
    (format t "~&x = ~S~%" x)
    (funcall x))
  (flet ((optimized ()
           (declare (optimize (speed 2) (debug 1))) ; tail call elimination
           (#:undefined-function 42))
         (not-optimized ()
           (declare (optimize (speed 1) (debug 2))) ; no tail call elimination
           (#:undefined-function 42))
         (test (fun)
           (declare (optimize (speed 1) (debug 2))) ; no tail call elimination
           (funcall fun)))
    (dolist (frame '(#-x86 "undefined function" ; bug 353
                     "FLET COMMON-LISP-USER::TEST"))
      (frob (lambda () (test #'optimized)))))
then typing BACKTRACE at the debug prompt, I get a reasonable-looking
backtrace
  0[1] backtr
  0: (SB-KERNEL::UNDEFINED-FUN-ERROR-HANDLER
      4
      #<unavailable argument>
      #.(SB-SYS:INT-SAP #X4035A7E0)
      #<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #X4035A4B0 :TYPE (*
                                                              (STRUCT
                                                               SB-VM::OS-CONTEXT-T-STRUCT))>
      (14))[:EXTERNAL]
  1: (SB-KERNEL:INTERNAL-ERROR
      2
      #.(SB-SYS:INT-SAP #X4035A4B0)
      #<unavailable argument>)[:EXTERNAL]
  2: ("foreign function: call_into_lisp")
  3: ("foreign function: funcall2")
  4: ("foreign function: interrupt_internal_error")
  5: ("foreign function: sigtrap_handler")
  6: ("foreign function: #x400676B0")
  7: ("FLET COMMON-LISP-USER::TEST"
      #<FUNCTION "FLET COMMON-LISP-USER::OPTIMIZED" {9731025}>)
  8: ("top level form (FLET (# # #) (DOLIST # #))")[:TOPLEVEL]
  ...
However, the corresponding automated test in debug.impure.lisp fails,
complaining of VERIFY-BACKTRACE-STUNTED.

My understanding of the debugger is mostly limited to superficial
interface stuff like BACKTRACE-AS-LIST. I have basically ignored 
nontrivial stuff like bugs in walking the stack. Thus, I'm far from
qualified to take one keen look at the failuire and understand its
significance. But my impression is that in this release this should be
treated as a known problem
        (test (fun)
          (declare (optimize (speed 1) (debug 2))) ; no tail call elimination
          (funcall fun)))
+  #-x86 ; <- known bug on 0.8.17.31/Linux/x86 -- WHN 2004-12-27
   (dolist (frame '(#-x86 "undefined function" ; bug 353
                    "FLET COMMON-LISP-USER::TEST"))
     (assert (verify-backtrace (lambda () (test #'optimized)) frame
without worrying about it too much.

-- 
William Harold Newman <wil...@ai...>
"Aha! A paradox for our time: Can God send a spam message that would get 
through His filters?"
  -- http://groups.google.com/groups?selm=slrncokcvq.5gd.dmsilev%40bardeen.uchicago.edu