From: Guillermo J. Rozas <edu/mit/csail/zurich/gjr>
Date: Wed, 2 Nov 1988 21:43:53 +0000 (+0000)
Subject: Fix bug by which attempting to print a bogus object would kill Scheme.
X-Git-Tag: 20090517-FFI~12467
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=ee1ea36f3d09d8db1901eadd56158787b73f9f44;p=mit-scheme.git

Fix bug by which attempting to print a bogus object would kill Scheme.
It now prints #[UNDEFINED-TYPE:<n> <datum>] and does NOT hash the object.
---

diff --git a/v7/src/runtime/unpars.scm b/v7/src/runtime/unpars.scm
index 7c7faca34..a3a85e6e8 100644
--- a/v7/src/runtime/unpars.scm
+++ b/v7/src/runtime/unpars.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/runtime/unpars.scm,v 14.7 1988/10/21 22:18:46 cph Exp $
+$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/runtime/unpars.scm,v 14.8 1988/11/02 21:43:53 jinx Exp $
 
 Copyright (c) 1988 Massachusetts Institute of Technology
 
@@ -207,12 +207,15 @@ MIT in each case. |#
 ;;;; Unparser Methods
 
 (define (unparse/default object)
-  (let ((type (user-object-type object)))
-    (if (zero? (object-gc-type object))
-	(*unparse-with-brackets type false
-	  (lambda ()
-	    (*unparse-datum object)))
-	(*unparse-with-brackets type object false))))
+  (let ((type (user-object-type object))
+	(gc-type ((ucode-primitive primitive-object-gc-type 1) object)))
+    (case gc-type
+      ((1 2 3 4 -3 -4)			; cell pair triple quad vector compiled
+       (*unparse-with-brackets type object false))
+      (else				; non pointer, gc special, undefined
+       (*unparse-with-brackets type false
+			       (lambda ()
+				 (*unparse-datum object)))))))
 
 (define (user-object-type object)
   (let ((type-code (object-type object)))