1 files changed, 15 insertions, 11 deletions

diff --git a/generic/tclEncoding.c b/generic/tclEncoding.c
index 15411d8..d246cb2 100644
--- a/generic/tclEncoding.c
+++ b/generic/tclEncoding.c
@@ -182,6 +182,7 @@ TCL_DECLARE_MUTEX(encodingMutex)
 
 static Tcl_Encoding defaultEncoding;
 static Tcl_Encoding systemEncoding;
+Tcl_Encoding tclIdentityEncoding;
 
 /*
  * The following variable is used in the sparse matrix code for a
@@ -270,7 +271,7 @@ static int		Iso88591ToUtfProc(ClientData clientData,
 			    int *dstCharsPtr);
 
 /*
- * A Tcl_ObjType for holding a cached Tcl_Encoding in the otherValuePtr field
+ * A Tcl_ObjType for holding a cached Tcl_Encoding in the twoPtrValue.ptr1 field
  * of the intrep. This should help the lifetime of encodings be more useful.
  * See concerns raised in [Bug 1077262].
  */
@@ -313,7 +314,7 @@ Tcl_GetEncodingFromObj(
 	    return TCL_ERROR;
 	}
 	TclFreeIntRep(objPtr);
-	objPtr->internalRep.otherValuePtr = encoding;
+	objPtr->internalRep.twoPtrValue.ptr1 = encoding;
 	objPtr->typePtr = &encodingType;
     }
     *encodingPtr = Tcl_GetEncoding(NULL, name);
@@ -334,7 +335,7 @@ static void
 FreeEncodingIntRep(
     Tcl_Obj *objPtr)
 {
-    Tcl_FreeEncoding(objPtr->internalRep.otherValuePtr);
+    Tcl_FreeEncoding(objPtr->internalRep.twoPtrValue.ptr1);
     objPtr->typePtr = NULL;
 }
 
@@ -353,7 +354,7 @@ DupEncodingIntRep(
     Tcl_Obj *srcPtr,
     Tcl_Obj *dupPtr)
 {
-    dupPtr->internalRep.otherValuePtr = Tcl_GetEncoding(NULL, srcPtr->bytes);
+    dupPtr->internalRep.twoPtrValue.ptr1 = Tcl_GetEncoding(NULL, srcPtr->bytes);
 }
 
 /*
@@ -567,7 +568,7 @@ TclInitEncodingSubsystem(void)
     type.freeProc	= NULL;
     type.nullSize	= 1;
     type.clientData	= NULL;
-    Tcl_CreateEncoding(&type);
+    tclIdentityEncoding = Tcl_CreateEncoding(&type);
 
     type.encodingName	= "utf-8";
     type.toUtfProc	= UtfExtToUtfIntProc;
@@ -651,6 +652,7 @@ TclFinalizeEncodingSubsystem(void)
     Tcl_MutexLock(&encodingMutex);
     encodingsInitialized = 0;
     FreeEncoding(systemEncoding);
+    FreeEncoding(tclIdentityEncoding);
 
     hPtr = Tcl_FirstHashEntry(&encodingTable, &search);
     while (hPtr != NULL) {
@@ -979,13 +981,13 @@ Tcl_GetEncodingNames(
 int
 Tcl_SetSystemEncoding(
     Tcl_Interp *interp,		/* Interp for error reporting, if not NULL. */
-    const char *name)		/* The name of the desired encoding, or NULL
+    const char *name)		/* The name of the desired encoding, or NULL/""
 				 * to reset to default encoding. */
 {
     Tcl_Encoding encoding;
     Encoding *encodingPtr;
 
-    if (name == NULL) {
+    if (!name || !*name) {
 	Tcl_MutexLock(&encodingMutex);
 	encoding = defaultEncoding;
 	encodingPtr = (Encoding *) encoding;
@@ -1542,7 +1544,8 @@ OpenEncodingFileChannel(
     }
 
     if ((NULL == chan) && (interp != NULL)) {
-	Tcl_AppendResult(interp, "unknown encoding \"", name, "\"", NULL);
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"unknown encoding \"%s\"", name));
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENCODING", name, NULL);
     }
     Tcl_DecrRefCount(fileNameObj);
@@ -1616,7 +1619,8 @@ LoadEncodingFile(
 	break;
     }
     if ((encoding == NULL) && (interp != NULL)) {
-	Tcl_AppendResult(interp, "invalid encoding file \"", name, "\"", NULL);
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"invalid encoding file \"%s\"", name));
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENCODING", name, NULL);
     }
     Tcl_Close(NULL, chan);
@@ -1872,9 +1876,9 @@ LoadTableEncoding(
      * Read lines from the encoding until EOF.
      */
 
-    for (Tcl_DStringSetLength(&lineString, 0);
+    for (TclDStringClear(&lineString);
 	    (len = Tcl_Gets(chan, &lineString)) >= 0;
-	    Tcl_DStringSetLength(&lineString, 0)) {
+	    TclDStringClear(&lineString)) {
 	const unsigned char *p;
 	int to, from;