Make TclLindexFlat() a litle more straightforward.

2 files changed, 36 insertions, 23 deletions

diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index 6cc933c..170dd69 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -2656,6 +2656,7 @@ TclLindexFlat(
     Tcl_Obj *const indexArray[])/* Array of pointers to Tcl objects that
 				 * represent the indices in the list. */
 {
+    int status;
     Tcl_Size i;
 
     /* Handle ArithSeries as special case */
@@ -2684,24 +2685,13 @@ TclLindexFlat(
 
     for (i=0 ; i<indexCount && listObj ; i++) {
 	Tcl_Size index, listLen = 0;
-	Tcl_Obj **elemPtrs = NULL, *sublistCopy;
+	Tcl_Obj **elemPtrs = NULL;
 
-	/*
-	 * Here we make a private copy of the current sublist, so we avoid any
-	 * shimmering issues that might invalidate the elemPtr array below
-	 * while we are still using it. See test lindex-8.4.
-	 */
-
-	sublistCopy = TclListObjCopy(interp, listObj);
-	Tcl_DecrRefCount(listObj);
-	listObj = NULL;
-
-	if (sublistCopy == NULL) {
-	    /* The sublist is not a list at all => error.  */
-	    break;
+	status = Tcl_ListObjLength(interp, listObj, &listLen);
+	if (status != TCL_OK) {
+	    Tcl_DecrRefCount(listObj);
+	    return NULL;
 	}
-	LIST_ASSERT_TYPE(sublistCopy);
-	ListObjGetElements(sublistCopy, listLen, elemPtrs);
 
 	if (TclGetIntForIndexM(interp, indexArray[i], /*endValue*/ listLen-1,
 		&index) == TCL_OK) {
@@ -2715,20 +2705,43 @@ TclLindexFlat(
 		    if (TclGetIntForIndexM(
 			    interp, indexArray[i], TCL_SIZE_MAX - 1, &index)
 			!= TCL_OK) {
-			Tcl_DecrRefCount(sublistCopy);
+			Tcl_DecrRefCount(listObj);
 			return NULL;
 		    }
 		}
+		Tcl_DecrRefCount(listObj);
 		TclNewObj(listObj);
+		Tcl_IncrRefCount(listObj);
 	    } else {
+		Tcl_Obj *itemObj;
+		/*
+		 * Must set the internal rep again because it may have been
+		 * changed by TclGetIntForIndexM. See test lindex-8.4.
+		 */
+		if (!TclHasInternalRep(listObj, &tclListType.objType)) {
+		    status = SetListFromAny(interp, listObj);
+		    if (status != TCL_OK) {
+			/* The list is not a list at all => error.  */
+			Tcl_DecrRefCount(listObj);
+			return NULL;
+		    }
+		}
+
+		ListObjGetElements(listObj, listLen, elemPtrs);
+		/* increment this reference count first before decrementing
+		 * just in case they are the same Tcl_Obj
+		 */
+		itemObj = elemPtrs[index];
+		Tcl_IncrRefCount(itemObj);
+		Tcl_DecrRefCount(listObj);
 		/* Extract the pointer to the appropriate element. */
-		listObj = elemPtrs[index];
+		listObj = itemObj;
 	    }
-	    Tcl_IncrRefCount(listObj);
+	} else {
+	    Tcl_DecrRefCount(listObj);
+	    listObj = NULL;
 	}
-	Tcl_DecrRefCount(sublistCopy);
     }
-
     return listObj;
 }
 
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index a5c1595..6112869 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -3799,8 +3799,8 @@ TclIndexEncode(
     }
     /*
      * We passed 2*INT_MAX as the "end value" to GetWideForIndex. The computed
-     * index will in one of the following ranges that need to be distinguished
-     * for encoding purposes in the following code.
+     * index will be in one of the following ranges that need to be
+     * distinguished for encoding purposes in the following code.
      * (1) 0:INT_MAX when
      *     (a) objPtr was a pure non-negative numeric value in that range
      *     (b) objPtr was a numeric computation M+/-N with a result in that range