interrupt causing infinite loop after type error

[Matt Kaufmann]

[As far as I know this is not the same as #404441. Otherwise,
my apologies.]

The following small example illustrates how interrupts can cause an
infinite loop that requires killing the session.

==============================

* (defun fib (n)
    (if (< n 2) 1 (+ (fib (- n 1)) (fib (- n 2)))))

FIB
* (trace fib)

(FIB)
* (fib 30)
  0: (FIB 30)
    1: (FIB 29)
....

<Interrupt with control-c>
0 ; to continue
<Interrupt with control-c>
0 ; to continue

; Then we get a type error followed by an infinite loop, as shown
; below.

0] 0

debugger invoked on a TYPE-ERROR in thread #<THREAD "initial thread" RUNNING
                                             {A9F5EE9}>:
  The value -22 is not of type (MOD 536870909).

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.

(SB-IMPL::WRITE-OUTPUT-FROM-QUEUE
 #<SB-SYS:FD-STREAM for "standard output" {A9F6661}>)
0]

debugger invoked on a TYPE-ERROR in thread #<THREAD "initial thread" RUNNING
                                             {A9F5EE9}>:
  The value NIL is not of type SB-IMPL::BUFFER.

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.

(SB-IMPL::WRITE-OUTPUT-FROM-QUEUE
 #<SB-SYS:FD-STREAM for "standard output" {A9F6661}>)
0[2]

==============================

Additional information, as requested by SBCL bug reporting guidelines:

lhug-8:~> sbcl-1.0.40 --version
SBCL 1.0.40
lhug-8:~> uname -a
Linux lhug-8.cs.utexas.edu 2.6.24.6.desktop11.28.75 #1 SMP Fri Aug 20 13:00:30 CDT 2010 i686 GNU/Linux
lhug-8:~> sbcl-1.0.40
This is SBCL 1.0.40, an implementation of ANSI Common Lisp.
More information about SBCL is available at <http://www.sbcl.org/>.

SBCL is free software, provided as is, with absolutely no warranty.
It is mostly in the public domain; some portions are provided under
BSD-style licenses. See the CREDITS and COPYING files in the
distribution for more information.
* *features*

(:ANSI-CL :COMMON-LISP :SBCL :SB-DOC :SB-TEST :SB-LDB :SB-PACKAGE-LOCKS
 :SB-UNICODE :SB-EVAL :SB-SOURCE-LOCATIONS :IEEE-FLOATING-POINT :X86 :UNIX :ELF
 :LINUX :SB-THREAD :LARGEFILE :GENCGC :STACK-GROWS-DOWNWARD-NOT-UPWARD
 :C-STACK-IS-CONTROL-STACK :COMPARE-AND-SWAP-VOPS :UNWIND-TO-FRAME-AND-CALL-VOP
 :RAW-INSTANCE-INIT-VOPS :STACK-ALLOCATABLE-CLOSURES :STACK-ALLOCATABLE-VECTORS
 :STACK-ALLOCATABLE-LISTS :STACK-ALLOCATABLE-FIXED-OBJECTS :ALIEN-CALLBACKS
 :CYCLE-COUNTER :INLINE-CONSTANTS :LINKAGE-TABLE :OS-PROVIDES-DLOPEN
 :OS-PROVIDES-PUTWC :OS-PROVIDES-SUSECONDS-T)
*

[Nikodemus Siivola (nikodemus)]

Confirmed on un-threaded x86-64 Darwin.