Problem using make-specializable

[Dawn MacLaughlin <dmaclaug@J.BBN.COM>]

In Symbolics 3670 Release 6.G2, IP-TCP 29.13, Release-6-7 6.0, BBN 35.0,
BFLY 8.0, Experimental PARCL 8.0, microcode TMC5-IO4-COL-MIC 388,
FEP 127, fep0:>v127-lisp.flod(44), fep0:>v127-loaders.flod(44),
fep0:>v127-info.flod(44), fep0:>v127-debug.flod(31), on Cod:

I'm using the 12/2/86 version of PCL on a Symbolics machine.  I have
defined a function called my-fun as (defun my-fun () nil).  I get the
following error when I call (make-specializable 'my-fun).  What gives?

>>Trap: The argument given to the CAR instruction, #<Discriminator
PCL:MY-FUN (:DAEMON) 56253444>, was not a locative, a list, or NIL.
While in the function REMPROP  PCL:|Method
REMOVE-DYNAMIC-SLOT-USING-CLASS BASIC-CLASS|  (:INTERNAL (:INTERNAL
#:G6784 0) 0)

REMPROP:  (P.C. = 31)
   Arg 0 (SI:SYM): #<DTP-LOCATIVE 74300300>
   Arg 1 (SI:INDICATOR): PCL:PRETTY-ARGLIST
   Local 2 (SI:PLLOC): #<DTP-LOCATIVE 74300300>
   Local 3: T
   Local 4 (SI:PL): #<Discriminator PCL:MY-FUN (:DAEMON) 56253444>
   Local 5 (SI:PPL): #<DTP-LOCATIVE 74300300>

PCL:|Method REMOVE-DYNAMIC-SLOT-USING-CLASS BASIC-CLASS|:  (P.C. = 4)
(from PARCL: PARCL; CLASS-SLOTS)
   Arg 0 (PCL:CLASS): #<Class PCL:DISCRIMINATOR 11340606>
   Arg 1 (PCL:OBJECT): #<Discriminator PCL:MY-FUN (:DAEMON) 56253444>
   Arg 2 (PCL:SLOT-NAME): PCL:PRETTY-ARGLIST

(:INTERNAL (:INTERNAL #:G6784 0) 0):  (P.C. = 45)
   Arg 0 (COMPILER:.LEXICAL-ENVIRONMENT-POINTER.): (#<Discriminator
PCL:REMOVE-DYNAMIC-SLOT-USING-CLASS (:DAEMON) 11334761> PCL:|Method
REMOVE-DYNAMIC-SLOT-USING-CLASS BASIC-CLASS| NIL #<Class PCL:BASIC-CLASS
11333112>)
   Arg 1 (PCL:|Discriminating Function Arg 0|): #<Class
PCL:DISCRIMINATOR 11340606>
   Arg 2 (PCL:|Discriminating Function Arg 1|): #<Discriminator
PCL:MY-FUN (:DAEMON) 56253444>
   Arg 3 (PCL:|Discriminating Function Arg 2|): PCL:PRETTY-ARGLIST

PCL:REMOVE-DYNAMIC-SLOT:  (P.C. = 6)  (from PARCL: PARCL; BRAID)
   Arg 0 (PCL:OBJECT): #<Discriminator PCL:MY-FUN (:DAEMON) 56253444>
   Arg 1 (PCL:SLOT-NAME): PCL:PRETTY-ARGLIST

(:INTERNAL PCL:MAKE-SPECIALIZABLE 0):  (P.C. = 141)
   Arg 0 (COMPILER:.LEXICAL-ENVIRONMENT-POINTER.): #<DTP-LOCATIVE
74300216>
   Rest arg: NIL

PCL:MAKE-SPECIALIZABLE:  (P.C. = 23)  (from PARCL: PARCL; METHODS)
   Arg 0 (PCL:FUNCTION-NAME): PCL:MY-FUN
   Rest arg (PCL:OPTIONS): NIL

SI:*EVAL:  (P.C. = 401)
   Arg 0 (SI:FORM): (PCL:MAKE-SPECIALIZABLE (QUOTE PCL:MY-FUN))
   Local 0 (SI:FORM): NIL
   --Defaulted args:--
   Arg 1 (SI:ENV): NIL
   Arg 2 (SI:HOOK): NIL

(:INTERNAL SI:LISP-COMMAND-LOOP-INTERNAL 0):  (P.C. = 152)
   Arg 0 (COMPILER:.LEXICAL-ENVIRONMENT-POINTER.): #<DTP-LOCATIVE
74300102>

Rest of stack:
TV:WITH-NOTIFICATION-MODE-INTERNAL:  (P.C. = 16)
SI:LISP-COMMAND-LOOP-INTERNAL:  (P.C. = 54)
SI:LISP-COMMAND-LOOP:  (P.C. = 67)
SI:COMMON-LISP-TOP-LEVEL:  (P.C. = 46)
SI:PROCESS-TOP-LEVEL:  (P.C. = 54)