1 files changed, 45 insertions, 20 deletions

diff --git a/generic/tclDictObj.c b/generic/tclDictObj.c
index 428173d..970978f 100644
--- a/generic/tclDictObj.c
+++ b/generic/tclDictObj.c
@@ -142,7 +142,7 @@ typedef struct Dict {
 				 * the entries in the order that they are
 				 * created. */
     int epoch;			/* Epoch counter */
-    int refcount;		/* Reference counter (see above) */
+    size_t refCount;		/* Reference counter (see above) */
     Tcl_Obj *chain;		/* Linked list used for invalidating the
 				 * string representations of updated nested
 				 * dictionaries. */
@@ -392,7 +392,7 @@ DupDictInternalRep(
 
     newDict->epoch = 0;
     newDict->chain = NULL;
-    newDict->refcount = 1;
+    newDict->refCount = 1;
 
     /*
      * Store in the object.
@@ -427,8 +427,7 @@ FreeDictInternalRep(
 {
     Dict *dict = DICT(dictPtr);
 
-    dict->refcount--;
-    if (dict->refcount <= 0) {
+    if (dict->refCount-- <= 1) {
 	DeleteDict(dict);
     }
     dictPtr->typePtr = NULL;
@@ -507,7 +506,7 @@ UpdateStringOfDict(
 
     /* Handle empty list case first, simplifies what follows */
     if (numElems == 0) {
-	dictPtr->bytes = tclEmptyStringRep;
+	dictPtr->bytes = &tclEmptyString;
 	dictPtr->length = 0;
 	return;
     }
@@ -713,7 +712,7 @@ SetDictFromAny(
     TclFreeIntRep(objPtr);
     dict->epoch = 0;
     dict->chain = NULL;
-    dict->refcount = 1;
+    dict->refCount = 1;
     DICT(objPtr) = dict;
     objPtr->internalRep.twoPtrValue.ptr2 = NULL;
     objPtr->typePtr = &tclDictType;
@@ -1117,7 +1116,7 @@ Tcl_DictObjFirst(
 	searchPtr->dictionaryPtr = (Tcl_Dict) dict;
 	searchPtr->epoch = dict->epoch;
 	searchPtr->next = cPtr->nextPtr;
-	dict->refcount++;
+	dict->refCount++;
 	if (keyPtrPtr != NULL) {
 	    *keyPtrPtr = Tcl_GetHashKey(&dict->table, &cPtr->entry);
 	}
@@ -1231,8 +1230,7 @@ Tcl_DictObjDone(
     if (searchPtr->epoch != -1) {
 	searchPtr->epoch = -1;
 	dict = (Dict *) searchPtr->dictionaryPtr;
-	dict->refcount--;
-	if (dict->refcount <= 0) {
+	if (dict->refCount-- <= 1) {
 	    DeleteDict(dict);
 	}
     }
@@ -1384,7 +1382,7 @@ Tcl_NewDictObj(void)
     InitChainTable(dict);
     dict->epoch = 0;
     dict->chain = NULL;
-    dict->refcount = 1;
+    dict->refCount = 1;
     DICT(dictPtr) = dict;
     dictPtr->internalRep.twoPtrValue.ptr2 = NULL;
     dictPtr->typePtr = &tclDictType;
@@ -1434,7 +1432,7 @@ Tcl_DbNewDictObj(
     InitChainTable(dict);
     dict->epoch = 0;
     dict->chain = NULL;
-    dict->refcount = 1;
+    dict->refCount = 1;
     DICT(dictPtr) = dict;
     dictPtr->internalRep.twoPtrValue.ptr2 = NULL;
     dictPtr->typePtr = &tclDictType;
@@ -2282,7 +2280,7 @@ 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 ...?");
@@ -2305,17 +2303,44 @@ 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_AppendObjToObj(valuePtr, 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);