TRACE of certain functions crashes SBCL into LDB

[Nikodemus Siivola]

As reported by Winton Davies on a CMU CL mailing list 2000-01-10,
and reported for SBCL by Martin Atzmueller 2000-10-20: (TRACE GETHASH)
crashes SBCL. In general tracing anything which is used in the
implementation of TRACE is likely to have the same problem.

CLHS allows this (tracing anything in CL is undefined), but it would be better
to fail gracefully.

[Attila Lendvai (attila-lendvai)]

i cannot reproduce this anymore. here's what i tried:

CL-USER> (TRACE GETHASH)
(GETHASH)
CL-USER> (gethash 42 (make-hash-table))
  0: (GETHASH 42 #<HASH-TABLE :TEST EQL :COUNT 0 {10090B8B63}>)
  0: GETHASH returned NIL NIL
NIL
NIL
CL-USER> (trace print)
(PRINT)
CL-USER> (gethash 42 (make-hash-table))
  0: (GETHASH 42 #<HASH-TABLE :TEST EQL :COUNT 0 {10090E9643}>)
  0: GETHASH returned NIL NIL
NIL
NIL
CL-USER> (trace format)
(FORMAT)
CL-USER> (gethash 42 (make-hash-table))
  0: (GETHASH 42 #<HASH-TABLE :TEST EQL :COUNT 0 {10091097A3}>)
  0: GETHASH returned NIL NIL
NIL
NIL
CL-USER> (format nil "foo")
  0: (FORMAT NIL "foo")
  0: FORMAT returned "foo"
"foo"
CL-USER> (trace car list)
(CAR LIST)
CL-USER> (car (list 42 43))
  0: (LIST 42 43)
  0: LIST returned (42 43)
  0: (CAR (42 43))
  0: CAR returned 42
42

[Stas Boukarev (stassats)]

That's not really an indicator, those functions are heavily transformed and rarely full-called.

[Douglas Katzman (dougk)]

Well, we have this, and we have https://bugs.launchpad.net/sbcl/+bug/1784517 which the reporter says "trace should signal an error".
If anything I'm more inclined to agree with this one, that it would be nice not to crash, maybe it's as simple as having a blacklist of functions not to trace.