1 files changed, 48 insertions, 19 deletions

diff --git a/generic/tclDictObj.c b/generic/tclDictObj.c
index 2eff1ff..3b983e3 100644
--- a/generic/tclDictObj.c
+++ b/generic/tclDictObj.c
@@ -141,7 +141,7 @@ typedef struct Dict {
 				 * the dictionary. Used for doing traversal of
 				 * the entries in the order that they are
 				 * created. */
-    int epoch;			/* Epoch counter */
+    unsigned int epoch; 	/* Epoch counter */
     size_t refCount;		/* Reference counter (see above) */
     Tcl_Obj *chain;		/* Linked list used for invalidating the
 				 * string representations of updated nested
@@ -390,7 +390,7 @@ DupDictInternalRep(
      * Initialise other fields.
      */
 
-    newDict->epoch = 0;
+    newDict->epoch = 1;
     newDict->chain = NULL;
     newDict->refCount = 1;
 
@@ -505,7 +505,7 @@ UpdateStringOfDict(
 
     /* Handle empty list case first, simplifies what follows */
     if (numElems == 0) {
-	dictPtr->bytes = tclEmptyStringRep;
+	dictPtr->bytes = &tclEmptyString;
 	dictPtr->length = 0;
 	return;
     }
@@ -707,7 +707,7 @@ SetDictFromAny(
      */
 
     TclFreeIntRep(objPtr);
-    dict->epoch = 0;
+    dict->epoch = 1;
     dict->chain = NULL;
     dict->refCount = 1;
     DICT(objPtr) = dict;
@@ -1106,7 +1106,7 @@ Tcl_DictObjFirst(
     dict = DICT(dictPtr);
     cPtr = dict->entryChainHead;
     if (cPtr == NULL) {
-	searchPtr->epoch = -1;
+	searchPtr->epoch = 0;
 	*donePtr = 1;
     } else {
 	*donePtr = 0;
@@ -1167,7 +1167,7 @@ Tcl_DictObjNext(
      * If the searh is done; we do no work.
      */
 
-    if (searchPtr->epoch == -1) {
+    if (!searchPtr->epoch) {
 	*donePtr = 1;
 	return;
     }
@@ -1224,8 +1224,8 @@ Tcl_DictObjDone(
 {
     Dict *dict;
 
-    if (searchPtr->epoch != -1) {
-	searchPtr->epoch = -1;
+    if (searchPtr->epoch) {
+	searchPtr->epoch = 0;
 	dict = (Dict *) searchPtr->dictionaryPtr;
 	if (dict->refCount-- <= 1) {
 	    DeleteDict(dict);
@@ -1377,7 +1377,7 @@ Tcl_NewDictObj(void)
     TclInvalidateStringRep(dictPtr);
     dict = ckalloc(sizeof(Dict));
     InitChainTable(dict);
-    dict->epoch = 0;
+    dict->epoch = 1;
     dict->chain = NULL;
     dict->refCount = 1;
     DICT(dictPtr) = dict;
@@ -1427,7 +1427,7 @@ Tcl_DbNewDictObj(
     TclInvalidateStringRep(dictPtr);
     dict = ckalloc(sizeof(Dict));
     InitChainTable(dict);
-    dict->epoch = 0;
+    dict->epoch = 1;
     dict->chain = NULL;
     dict->refCount = 1;
     DICT(dictPtr) = dict;
@@ -2277,7 +2277,7 @@ DictAppendCmd(
     Tcl_Obj *const *objv)
 {
     Tcl_Obj *dictPtr, *valuePtr, *resultPtr;
-    int i, allocatedDict = 0;
+    int allocatedDict = 0;
 
     if (objc < 3) {
 	Tcl_WrongNumArgs(interp, 1, objv, "dictVarName key ?value ...?");
@@ -2300,17 +2300,46 @@ DictAppendCmd(
 	return TCL_ERROR;
     }
 
-    if (valuePtr == NULL) {
-	TclNewObj(valuePtr);
-    } else if (Tcl_IsShared(valuePtr)) {
-	valuePtr = Tcl_DuplicateObj(valuePtr);
-    }
+    if ((objc > 3) || (valuePtr == NULL)) {
+	/* Only go through append activites when something will change. */
+	Tcl_Obj *appendObjPtr = NULL;
 
-    for (i=3 ; i<objc ; i++) {
-	Tcl_AppendObjToObj(valuePtr, objv[i]);
+	if (objc > 3) {
+	    /* Something to append */
+
+	    if (objc == 4) {
+		appendObjPtr = objv[3];
+	    } else if (TCL_OK != TclStringCatObjv(interp, /* inPlace */ 1,
+		    objc-3, objv+3, &appendObjPtr)) {
+		return TCL_ERROR;
+	    }
+	}
+
+	if (appendObjPtr == NULL) {
+	    /* => (objc == 3) => (valuePtr == NULL) */
+	    TclNewObj(valuePtr);
+	} else if (valuePtr == NULL) {
+	    valuePtr = appendObjPtr;
+	    appendObjPtr = NULL;
+	}
+
+	if (appendObjPtr) {
+	    if (Tcl_IsShared(valuePtr)) {
+		valuePtr = Tcl_DuplicateObj(valuePtr);
+	    }
+
+	    Tcl_IncrRefCount(appendObjPtr);
+	    Tcl_AppendObjToObj(valuePtr, appendObjPtr);
+	    Tcl_DecrRefCount(appendObjPtr);
+	}
+
+	Tcl_DictObjPut(NULL, dictPtr, objv[2], valuePtr);
     }
 
-    Tcl_DictObjPut(NULL, dictPtr, objv[2], valuePtr);
+    /*
+     * Even if nothing changed, we still overwrite so that variable
+     * trace expectations are met.
+     */
 
     resultPtr = Tcl_ObjSetVar2(interp, objv[1], NULL, dictPtr,
 	    TCL_LEAVE_ERR_MSG);