SBCL

problem with backtraces with DX rest and type-errors from THE

Bug #795245 reported by Nikodemus Siivola on 2011-06-09

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	SBCL	Triaged	Low	Unassigned

   (defun oops (x &rest args)
     (declare (dynamic-extent args))
     (the number x)
     (length args))

(oops nil 1)

debugger invoked on a TYPE-ERROR: The value NIL is not of type NUMBER.

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
0: [ABORT] Exit debugger, returning to top level.

debugger invoked on a TYPE-ERROR:
The value #<invalid object #x11FF4C7> is not of type SEQUENCE.

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
0: [ABORT] Exit debugger, returning to top level.

(REVERSE #<invalid object #x11FF4C7>)[:EXTERNAL]
0[2]

The error occurs trying to reverse the rest-list -- which isn't what the debugger expect it to be.

Tags:

Revision history for this message

Nikodemus Siivola (nikodemus) wrote on 2011-06-09:

Changing the THE to (DECLARE (NUMBER X)) makes things come out right.

Revision history for this message

Nikodemus Siivola (nikodemus) wrote on 2011-06-09:

Workaround committed. The actual issue of invalid object where the &rest should be remains.

commit bddb383d464b924f1066f1733fe8e2407e7d9283
Author: Nikodemus Siivola <email address hidden>
Date: Thu Jun 9 23:23:23 2011 +0300

robustify debugger against bogus lambda-lists

If we don't find a list where we expect a rest-list to be,
substitute a dummy unprintable object.

Provides a workaround for lp#795245.

Changed in sbcl:
importance:	Undecided → Medium
status:	New → Triaged
tags:	added: compiler debugger dynamic-extent
Changed in sbcl:
importance:	Medium → Low

Revision history for this message

Nikodemus Siivola (nikodemus) wrote on 2011-06-09:

Of the following, BAR and ZOT exhibit the problem.

(defun bar (x &rest args)
(declare (dynamic-extent args))
(values (the number x) (length args)))

(defun zot (x &rest args)
  (declare (dynamic-extent args))
  (locally
      (declare (number x))
    (values x (length args))))

(defun foo (x &rest args)
(values (the number x) (length args)))

(defun quux (x &rest args)
  (declare (dynamic-extent args))
  (declare (number x))
  (values x (length args)))

(defun fii (x &rest args)
  (declare (dynamic-extent fii))
  (if x
      (error "foo")
      (length args)))

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