From: Chris Hanson <org/chris-hanson/cph>
Date: Sat, 6 May 2017 06:18:16 +0000 (-0700)
Subject: Fix bug: incorrect assumption of mutability.
X-Git-Tag: mit-scheme-pucked-9.2.12~14^2~77
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=c8da9c501c8ad0945499688151b57766af659e15;p=mit-scheme.git

Fix bug: incorrect assumption of mutability.
---

diff --git a/src/runtime/dbgutl.scm b/src/runtime/dbgutl.scm
index 50e6512ab..2edadb2ba 100644
--- a/src/runtime/dbgutl.scm
+++ b/src/runtime/dbgutl.scm
@@ -94,8 +94,9 @@ USA.
 	       (parameterize* (list (cons current-output-port port))
 			      thunk)))))
       (if (and (car x) (> length 4))
-	  (string-copy! (cdr x) (- length 4) " ..."))
-      (cdr x))))
+	  (string-append (string-slice (cdr x) 0 (- length 4))
+			 " ...")
+	  (cdr x)))))
 
 (define (show-frames environment depth port)
   (debugger-presentation port