Flavor bug

[Gavan Duffy <gavan@emx.utexas.edu>]

   Date: Sat, 21 May 88 14:05 EDT
   From: SWM@SAPSUCKER.SCRC.Symbolics.COM (Scott McKay)

       Date: Fri, 20 May 88 13:09:38 pdt
       From: ragosa%psyche@BOEING.COM 

       The following code causes a crash to the FEP when compiled. A fellow
       employee discovered it and asked me to forward it to BUG-LISPM and SLUG.
       It fails under Genera 7.1. The reference to LENGTH is the problem. 

       ;;; -*- Mode: LISP; Syntax: Common-lisp; Package: USER; Base: 10 -*-

       ; Flavor bug. The reference to LENGTH (a CommonLISP function) seems to
       ; be the culprit. Try to compile this (Note: Prepare for an irrevokable
       ; crash to the FEP).

       (defflavor test ((length nil)) ()
	 (:writable-instance-variables (length length)))

   I presume that you at least got a redefinition warning for LENGTH when
   you did this?  If not, that is a bug. 

Where is length redefined?  It's specified here as an instance variable,
not a function.  TEST-LENGTH is defined, but not LENGTH.  

   However, if you did get a redefinition warning, and told it to go
   ahead, then the fact that you lost is not a bug.  LENGTH is a
   critical function, and redefining it is bound to cause you to lose.

In general, it's helpful to lose gracefully.  I haven't yet been
courageous enough to try this, so I don't know whether it really throws
you into the FEP, but if it does that's not very graceful.  The
debugger's a much better place to be.