*** tcl8.3.2/generic/tclCmdMZ.c Mon Apr 10 17:08:26 2000
--- tcl8.3.2-patch/generic/tclCmdMZ.c   Thu Aug 24 21:03:51 2000
***************
*** 2626,2633 ****
                                TraceVarProc, clientData);
                        if (tvarPtr->errMsg != NULL) {
                            ckfree(tvarPtr->errMsg);
                        }
!                       ckfree((char *) tvarPtr);
                        break;
                    }
                }
--- 2626,2634 ----
                                TraceVarProc, clientData);
                        if (tvarPtr->errMsg != NULL) {
                            ckfree(tvarPtr->errMsg);
+                           tvarPtr->errMsg = NULL;
                        }
!                       Tcl_EventuallyFree((ClientData) tvarPtr, TCL_DYNAMIC);
                        break;
                    }
                }
***************
*** 2729,2734 ****
--- 2730,2745 ----
      int code;
      Tcl_DString cmd;
  
+     /* 
+      * We might call Tcl_Eval() below, and that might evaluate
+      * [trace vdelete] which might try to free tvarPtr.  We want
+      * to use tvarPtr until the end of this function, so we use
+      * Tcl_Preserve() and Tcl_Release() to be sure it is not 
+      * freed while we still need it.
+      */
+ 
+     Tcl_Preserve((ClientData) tvarPtr);
+ 
      result = NULL;
      if (tvarPtr->errMsg != NULL) {
        ckfree(tvarPtr->errMsg);
***************
*** 2784,2792 ****
        result = NULL;
        if (tvarPtr->errMsg != NULL) {
            ckfree(tvarPtr->errMsg);
        }
!       ckfree((char *) tvarPtr);
      }
      return result;
  }
  ^L
--- 2795,2810 ----
        result = NULL;
        if (tvarPtr->errMsg != NULL) {
            ckfree(tvarPtr->errMsg);
+           tvarPtr->errMsg = NULL;
        }
!       Tcl_EventuallyFree((ClientData) tvarPtr, TCL_DYNAMIC);
      }
+ 
+     /*
+      * Match for Tcl_Preserve() near start of this function.
+      */
+ 
+     Tcl_Release((ClientData) tvarPtr);
      return result;
  }
  ^L