merge trunk

21 files changed, 2072 insertions, 458 deletions

diff --git a/generic/tclAssembly.c b/generic/tclAssembly.c
index 03177b9..7b775a9 100644
--- a/generic/tclAssembly.c
+++ b/generic/tclAssembly.c
@@ -26,6 +26,7 @@
  *-   jumpTable testing
  *-   syntax (?)
  *-   returnCodeBranch
+ *-   tclooNext, tclooNextClass
  */
 
 #include "tclInt.h"
@@ -349,7 +350,8 @@ static const TalInstDesc TalInstructionTable[] = {
     {"bitnot",		ASSEM_1BYTE,	INST_BITNOT,		1,	1},
     {"bitor",		ASSEM_1BYTE,	INST_BITOR,		2,	1},
     {"bitxor",		ASSEM_1BYTE,	INST_BITXOR,		2,	1},
-    {"concat",		ASSEM_CONCAT1,	INST_CONCAT1,		INT_MIN,1},
+    {"concat",		ASSEM_CONCAT1,	INST_STR_CONCAT1,	INT_MIN,1},
+    {"concatStk",	ASSEM_LIST,	INST_CONCAT_STK,	INT_MIN,1},
     {"coroName",	ASSEM_1BYTE,	INST_COROUTINE_NAME,	0,	1},
     {"currentNamespace",ASSEM_1BYTE,	INST_NS_CURRENT,	0,	1},
     {"dictAppend",	ASSEM_LVT4,	INST_DICT_APPEND,	2,	1},
@@ -436,6 +438,7 @@ static const TalInstDesc TalInstructionTable[] = {
     {"nop",		ASSEM_1BYTE,	INST_NOP,		0,	0},
     {"not",		ASSEM_1BYTE,	INST_LNOT,		1,	1},
     {"nsupvar",		ASSEM_LVT4,	INST_NSUPVAR,		2,	1},
+    {"originCmd",	ASSEM_1BYTE,	INST_ORIGIN_COMMAND,	1,	1},
     {"over",		ASSEM_OVER,	INST_OVER,		INT_MIN,-1-1},
     {"pop",		ASSEM_1BYTE,	INST_POP,		1,	0},
     {"pushReturnCode",	ASSEM_1BYTE,	INST_PUSH_RETURN_CODE,	0,	1},
@@ -452,7 +455,11 @@ static const TalInstDesc TalInstructionTable[] = {
 					 | INST_STORE_ARRAY4),	2,	1},
     {"storeArrayStk",	ASSEM_1BYTE,	INST_STORE_ARRAY_STK,	3,	1},
     {"storeStk",	ASSEM_1BYTE,	INST_STORE_STK,		2,	1},
+    {"strcaseLower",	ASSEM_1BYTE,	INST_STR_LOWER,		1,	1},
+    {"strcaseTitle",	ASSEM_1BYTE,	INST_STR_TITLE,		1,	1},
+    {"strcaseUpper",	ASSEM_1BYTE,	INST_STR_UPPER,		1,	1},
     {"strcmp",		ASSEM_1BYTE,	INST_STR_CMP,		2,	1},
+    {"strcat",		ASSEM_CONCAT1,	INST_STR_CONCAT1,	INT_MIN,1},
     {"streq",		ASSEM_1BYTE,	INST_STR_EQ,		2,	1},
     {"strfind",		ASSEM_1BYTE,	INST_STR_FIND,		2,	1},
     {"strindex",	ASSEM_1BYTE,	INST_STR_INDEX,		2,	1},
@@ -461,7 +468,11 @@ static const TalInstDesc TalInstructionTable[] = {
     {"strmatch",	ASSEM_BOOL,	INST_STR_MATCH,		2,	1},
     {"strneq",		ASSEM_1BYTE,	INST_STR_NEQ,		2,	1},
     {"strrange",	ASSEM_1BYTE,	INST_STR_RANGE,		3,	1},
+    {"strreplace",	ASSEM_1BYTE,	INST_STR_REPLACE,	4,	1},
     {"strrfind",	ASSEM_1BYTE,	INST_STR_FIND_LAST,	2,	1},
+    {"strtrim",		ASSEM_1BYTE,	INST_STR_TRIM,		2,	1},
+    {"strtrimLeft",	ASSEM_1BYTE,	INST_STR_TRIM_LEFT,	2,	1},
+    {"strtrimRight",	ASSEM_1BYTE,	INST_STR_TRIM_RIGHT,	2,	1},
     {"sub",		ASSEM_1BYTE,	INST_SUB,		2,	1},
     {"tclooClass",	ASSEM_1BYTE,	INST_TCLOO_CLASS,	1,	1},
     {"tclooIsObject",	ASSEM_1BYTE,	INST_TCLOO_IS_OBJECT,	1,	1},
@@ -493,6 +504,7 @@ static const unsigned char NonThrowingByteCodes[] = {
     INST_PUSH1, INST_PUSH4, INST_POP, INST_DUP,			/* 1-4 */
     INST_JUMP1, INST_JUMP4,					/* 34-35 */
     INST_END_CATCH, INST_PUSH_RESULT, INST_PUSH_RETURN_CODE,	/* 70-72 */
+    INST_LIST,							/* 79 */
     INST_OVER,							/* 95 */
     INST_PUSH_RETURN_OPTIONS,					/* 108 */
     INST_REVERSE,						/* 126 */
@@ -502,7 +514,10 @@ static const unsigned char NonThrowingByteCodes[] = {
     INST_COROUTINE_NAME,					/* 149 */
     INST_NS_CURRENT,						/* 151 */
     INST_INFO_LEVEL_NUM,					/* 152 */
-    INST_RESOLVE_COMMAND					/* 154 */
+    INST_RESOLVE_COMMAND,					/* 154 */
+    INST_STR_TRIM, INST_STR_TRIM_LEFT, INST_STR_TRIM_RIGHT,	/* 166-168 */
+    INST_CONCAT_STK,						/* 169 */
+    INST_STR_UPPER, INST_STR_LOWER, INST_STR_TITLE		/* 170-172 */
 };
 
 /*
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index d18bdda..0e52cb6 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -194,7 +194,7 @@ static const CmdInfo builtInCmds[] = {
     {"apply",		Tcl_ApplyObjCmd,	NULL,			TclNRApplyObjCmd,	CMD_IS_SAFE},
     {"break",		Tcl_BreakObjCmd,	TclCompileBreakCmd,	NULL,	CMD_IS_SAFE},
     {"catch",		Tcl_CatchObjCmd,	TclCompileCatchCmd,	TclNRCatchObjCmd,	CMD_IS_SAFE},
-    {"concat",		Tcl_ConcatObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
+    {"concat",		Tcl_ConcatObjCmd,	TclCompileConcatCmd,	NULL,	CMD_IS_SAFE},
     {"continue",	Tcl_ContinueObjCmd,	TclCompileContinueCmd,	NULL,	CMD_IS_SAFE},
     {"coroutine",	NULL,			NULL,			TclNRCoroutineObjCmd,	CMD_IS_SAFE},
     {"error",		Tcl_ErrorObjCmd,	TclCompileErrorCmd,	NULL,	CMD_IS_SAFE},
@@ -210,7 +210,7 @@ static const CmdInfo builtInCmds[] = {
     {"lappend",		Tcl_LappendObjCmd,	TclCompileLappendCmd,	NULL,	CMD_IS_SAFE},
     {"lassign",		Tcl_LassignObjCmd,	TclCompileLassignCmd,	NULL,	CMD_IS_SAFE},
     {"lindex",		Tcl_LindexObjCmd,	TclCompileLindexCmd,	NULL,	CMD_IS_SAFE},
-    {"linsert",		Tcl_LinsertObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
+    {"linsert",		Tcl_LinsertObjCmd,	TclCompileLinsertCmd,	NULL,	CMD_IS_SAFE},
     {"list",		Tcl_ListObjCmd,		TclCompileListCmd,	NULL,	CMD_IS_SAFE|CMD_COMPILES_EXPANDED},
     {"llength",		Tcl_LlengthObjCmd,	TclCompileLlengthCmd,	NULL,	CMD_IS_SAFE},
     {"lmap",		Tcl_LmapObjCmd,		TclCompileLmapCmd,	TclNRLmapCmd,	CMD_IS_SAFE},
@@ -242,7 +242,7 @@ static const CmdInfo builtInCmds[] = {
     {"variable",	Tcl_VariableObjCmd,	TclCompileVariableCmd,	NULL,	CMD_IS_SAFE},
     {"while",		Tcl_WhileObjCmd,	TclCompileWhileCmd,	TclNRWhileObjCmd,	CMD_IS_SAFE},
     {"yield",		NULL,			TclCompileYieldCmd,	TclNRYieldObjCmd,	CMD_IS_SAFE},
-    {"yieldto",		NULL,			NULL,			TclNRYieldToObjCmd,	CMD_IS_SAFE},
+    {"yieldto",		NULL,			TclCompileYieldToCmd,	TclNRYieldToObjCmd,	CMD_IS_SAFE},
 
     /*
      * Commands in the OS-interface. Note that many of these are unsafe.
@@ -7703,8 +7703,7 @@ TclNRYieldToObjCmd(
 {
     CoroutineData *corPtr = iPtr->execEnvPtr->corPtr;
     Tcl_Obj *listPtr, *nsObjPtr;
-    Tcl_Namespace *nsPtr = (Tcl_Namespace *) iPtr->varFramePtr->nsPtr;
-    Tcl_Namespace *ns1Ptr;
+    Tcl_Namespace *nsPtr = TclGetCurrentNamespace(interp);
 
     if (objc < 2) {
 	Tcl_WrongNumArgs(interp, 1, objv, "command ?arg ...?");
@@ -7718,11 +7717,13 @@ TclNRYieldToObjCmd(
 	return TCL_ERROR;
     }
 
-    /*
-     * Add the tailcall in the caller env, then just yield.
-     *
-     * This is essentially code from TclNRTailcallObjCmd
-     */
+    if (((Namespace *) nsPtr)->flags & NS_DYING) {
+        Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"yieldto called in deleted namespace", -1));
+        Tcl_SetErrorCode(interp, "TCL", "COROUTINE", "YIELDTO_IN_DELETED",
+		NULL);
+        return TCL_ERROR;
+    }
 
     /*
      * Add the tailcall in the caller env, then just yield.
@@ -7731,15 +7732,9 @@ TclNRYieldToObjCmd(
      */
 
     listPtr = Tcl_NewListObj(objc, objv);
-
     nsObjPtr = Tcl_NewStringObj(nsPtr->fullName, -1);
-    if ((TCL_OK != TclGetNamespaceFromObj(interp, nsObjPtr, &ns1Ptr))
-	    || (nsPtr != ns1Ptr)) {
-	Tcl_Panic("yieldto failed to find the proper namespace");
-    }
     TclListObjSetElement(interp, listPtr, 0, nsObjPtr);
 
-
     /*
      * Add the callback in the caller's env, then instruct TEBC to yield.
      */
diff --git a/generic/tclBinary.c b/generic/tclBinary.c
index 9bbc011..7398fc2 100644
--- a/generic/tclBinary.c
+++ b/generic/tclBinary.c
@@ -610,9 +610,7 @@ UpdateStringOfByteArray(
  *
  *	This function appends an array of bytes to a byte array object. Note
  *	that the object *must* be unshared, and the array of bytes *must not*
- *	refer to the object being appended to.  Also the caller must have
- *	already checked that the final length of the bytearray after the
- *	append operations is complete will not overflow the int range.
+ *	refer to the object being appended to.
  *
  * Results:
  *	None.
@@ -631,6 +629,7 @@ TclAppendBytesToByteArray(
     int len)
 {
     ByteArray *byteArrayPtr;
+    int needed;
 
     if (Tcl_IsShared(objPtr)) {
 	Tcl_Panic("%s called with shared object","TclAppendBytesToByteArray");
@@ -639,64 +638,57 @@ TclAppendBytesToByteArray(
 	Tcl_Panic("%s must be called with definite number of bytes to append",
 		"TclAppendBytesToByteArray");
     }
+    if (len == 0) {
+	/* Append zero bytes is a no-op. */
+	return;
+    }
     if (objPtr->typePtr != &tclByteArrayType) {
 	SetByteArrayFromAny(NULL, objPtr);
     }
     byteArrayPtr = GET_BYTEARRAY(objPtr);
 
+    if (len > INT_MAX - byteArrayPtr->used) {
+	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
+    }
+
+    needed = byteArrayPtr->used + len;
     /*
      * If we need to, resize the allocated space in the byte array.
      */
 
-    if (byteArrayPtr->used + len > byteArrayPtr->allocated) {
-	unsigned int attempt, used = byteArrayPtr->used;
-	ByteArray *tmpByteArrayPtr = NULL;
+    if (needed > byteArrayPtr->allocated) {
+	ByteArray *ptr = NULL;
+	int attempt;
 
-	attempt = byteArrayPtr->allocated;
-	if (attempt < 1) {
-	    /*
-	     * No allocated bytes, so must be none used too. We use this
-	     * method to calculate how many bytes to allocate because we can
-	     * end up with a zero-length buffer otherwise, when doubling can
-	     * cause trouble. [Bug 3067036]
-	     */
-
-	    attempt = len + 1;
-	} else {
-	    do {
-		attempt *= 2;
-	    } while (attempt < used+len);
+	if (needed <= INT_MAX/2) {
+	    /* Try to allocate double the total space that is needed. */
+	    attempt = 2 * needed;
+	    ptr = attemptckrealloc(byteArrayPtr, BYTEARRAY_SIZE(attempt));
 	}
+	if (ptr == NULL) {
+	    /* Try to allocate double the increment that is needed (plus). */
+	    unsigned int limit = INT_MAX - needed;
+	    unsigned int extra = len + TCL_MIN_GROWTH;
+	    int growth = (int) ((extra > limit) ? limit : extra);
 
-	if (BYTEARRAY_SIZE(attempt) > BYTEARRAY_SIZE(used)) {
-	    tmpByteArrayPtr = attemptckrealloc(byteArrayPtr,
-		    BYTEARRAY_SIZE(attempt));
+	    attempt = needed + growth;
+	    ptr = attemptckrealloc(byteArrayPtr, BYTEARRAY_SIZE(attempt));
 	}
-
-	if (tmpByteArrayPtr == NULL) {
-	    attempt = used + len;
-	    if (BYTEARRAY_SIZE(attempt) < BYTEARRAY_SIZE(used)) {
-		Tcl_Panic("attempt to allocate a bigger buffer than we can handle");
-	    }
-	    tmpByteArrayPtr = ckrealloc(byteArrayPtr,
-		    BYTEARRAY_SIZE(attempt));
+	if (ptr == NULL) {
+	    /* Last chance: Try to allocate exactly what is needed. */
+	    attempt = needed;
+	    ptr = ckrealloc(byteArrayPtr, BYTEARRAY_SIZE(attempt));
 	}
-
-	byteArrayPtr = tmpByteArrayPtr;
+	byteArrayPtr = ptr;
 	byteArrayPtr->allocated = attempt;
-	byteArrayPtr->used = used;
 	SET_BYTEARRAY(objPtr, byteArrayPtr);
     }
 
-    /*
-     * Do the append if there's any point.
-     */
-
-    if (len > 0) {
+    if (bytes) {
 	memcpy(byteArrayPtr->bytes + byteArrayPtr->used, bytes, len);
-	byteArrayPtr->used += len;
-	TclInvalidateStringRep(objPtr);
     }
+    byteArrayPtr->used += len;
+    TclInvalidateStringRep(objPtr);
 }
 
 /*
diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index 5d1820c..61482b7 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -18,6 +18,7 @@
 
 #include "tclInt.h"
 #include "tclRegexp.h"
+#include "tclStringTrim.h"
 
 static inline Tcl_Obj *	During(Tcl_Interp *interp, int resultCode,
 			    Tcl_Obj *oldOptions, Tcl_Obj *errorInfo);
@@ -37,32 +38,33 @@ static int		UniCharIsHexDigit(int character);
  * UTF-8 literal string containing all Unicode space characters [TIP #413]
  */
 
-#define DEFAULT_TRIM_SET \
-	"\x09\x0a\x0b\x0c\x0d " /* ASCII */\
-	"\xc0\x80" /*     nul (U+0000) */\
-	"\xc2\x85" /*     next line (U+0085) */\
-	"\xc2\xa0" /*     non-breaking space (U+00a0) */\
-	"\xe1\x9a\x80" /* ogham space mark (U+1680) */ \
-	"\xe1\xa0\x8e" /* mongolian vowel separator (U+180e) */\
-	"\xe2\x80\x80" /* en quad (U+2000) */\
-	"\xe2\x80\x81" /* em quad (U+2001) */\
-	"\xe2\x80\x82" /* en space (U+2002) */\
-	"\xe2\x80\x83" /* em space (U+2003) */\
-	"\xe2\x80\x84" /* three-per-em space (U+2004) */\
-	"\xe2\x80\x85" /* four-per-em space (U+2005) */\
-	"\xe2\x80\x86" /* six-per-em space (U+2006) */\
-	"\xe2\x80\x87" /* figure space (U+2007) */\
-	"\xe2\x80\x88" /* punctuation space (U+2008) */\
-	"\xe2\x80\x89" /* thin space (U+2009) */\
-	"\xe2\x80\x8a" /* hair space (U+200a) */\
-	"\xe2\x80\x8b" /* zero width space (U+200b) */\
-	"\xe2\x80\xa8" /* line separator (U+2028) */\
-	"\xe2\x80\xa9" /* paragraph separator (U+2029) */\
-	"\xe2\x80\xaf" /* narrow no-break space (U+202f) */\
-	"\xe2\x81\x9f" /* medium mathematical space (U+205f) */\
-	"\xe2\x81\xa0" /* word joiner (U+2060) */\
-	"\xe3\x80\x80" /* ideographic space (U+3000) */\
+const char tclDefaultTrimSet[] = 
+	"\x09\x0a\x0b\x0c\x0d " /* ASCII */
+	"\xc0\x80" /*     nul (U+0000) */
+	"\xc2\x85" /*     next line (U+0085) */
+	"\xc2\xa0" /*     non-breaking space (U+00a0) */
+	"\xe1\x9a\x80" /* ogham space mark (U+1680) */
+	"\xe1\xa0\x8e" /* mongolian vowel separator (U+180e) */
+	"\xe2\x80\x80" /* en quad (U+2000) */
+	"\xe2\x80\x81" /* em quad (U+2001) */
+	"\xe2\x80\x82" /* en space (U+2002) */
+	"\xe2\x80\x83" /* em space (U+2003) */
+	"\xe2\x80\x84" /* three-per-em space (U+2004) */
+	"\xe2\x80\x85" /* four-per-em space (U+2005) */
+	"\xe2\x80\x86" /* six-per-em space (U+2006) */
+	"\xe2\x80\x87" /* figure space (U+2007) */
+	"\xe2\x80\x88" /* punctuation space (U+2008) */
+	"\xe2\x80\x89" /* thin space (U+2009) */
+	"\xe2\x80\x8a" /* hair space (U+200a) */
+	"\xe2\x80\x8b" /* zero width space (U+200b) */
+	"\xe2\x80\xa8" /* line separator (U+2028) */
+	"\xe2\x80\xa9" /* paragraph separator (U+2029) */
+	"\xe2\x80\xaf" /* narrow no-break space (U+202f) */
+	"\xe2\x81\x9f" /* medium mathematical space (U+205f) */
+	"\xe2\x81\xa0" /* word joiner (U+2060) */
+	"\xe3\x80\x80" /* ideographic space (U+3000) */
 	"\xef\xbb\xbf" /* zero width no-break space (U+feff) */
+;
 
 /*
  *----------------------------------------------------------------------
@@ -3189,8 +3191,8 @@ StringTrimCmd(
     if (objc == 3) {
 	string2 = TclGetStringFromObj(objv[2], &length2);
     } else if (objc == 2) {
-	string2 = DEFAULT_TRIM_SET;
-	length2 = strlen(DEFAULT_TRIM_SET);
+	string2 = tclDefaultTrimSet;
+	length2 = strlen(tclDefaultTrimSet);
     } else {
 	Tcl_WrongNumArgs(interp, 1, objv, "string ?chars?");
 	return TCL_ERROR;
@@ -3237,8 +3239,8 @@ StringTrimLCmd(
     if (objc == 3) {
 	string2 = TclGetStringFromObj(objv[2], &length2);
     } else if (objc == 2) {
-	string2 = DEFAULT_TRIM_SET;
-	length2 = strlen(DEFAULT_TRIM_SET);
+	string2 = tclDefaultTrimSet;
+	length2 = strlen(tclDefaultTrimSet);
     } else {
 	Tcl_WrongNumArgs(interp, 1, objv, "string ?chars?");
 	return TCL_ERROR;
@@ -3283,8 +3285,8 @@ StringTrimRCmd(
     if (objc == 3) {
 	string2 = TclGetStringFromObj(objv[2], &length2);
     } else if (objc == 2) {
-	string2 = DEFAULT_TRIM_SET;
-	length2 = strlen(DEFAULT_TRIM_SET);
+	string2 = tclDefaultTrimSet;
+	length2 = strlen(tclDefaultTrimSet);
     } else {
 	Tcl_WrongNumArgs(interp, 1, objv, "string ?chars?");
 	return TCL_ERROR;
@@ -3337,14 +3339,14 @@ TclInitStringCmd(
 	{"match",	StringMatchCmd,	TclCompileStringMatchCmd, NULL, NULL, 0},
 	{"range",	StringRangeCmd,	TclCompileStringRangeCmd, NULL, NULL, 0},
 	{"repeat",	StringReptCmd,	TclCompileBasic2ArgCmd, NULL, NULL, 0},
-	{"replace",	StringRplcCmd,	NULL, NULL, NULL, 0},
+	{"replace",	StringRplcCmd,	TclCompileStringReplaceCmd, NULL, NULL, 0},
 	{"reverse",	StringRevCmd,	TclCompileBasic1ArgCmd, NULL, NULL, 0},
-	{"tolower",	StringLowerCmd,	TclCompileBasic1To3ArgCmd, NULL, NULL, 0},
-	{"toupper",	StringUpperCmd,	TclCompileBasic1To3ArgCmd, NULL, NULL, 0},
-	{"totitle",	StringTitleCmd,	TclCompileBasic1To3ArgCmd, NULL, NULL, 0},
-	{"trim",	StringTrimCmd,	TclCompileBasic1Or2ArgCmd, NULL, NULL, 0},
-	{"trimleft",	StringTrimLCmd,	TclCompileBasic1Or2ArgCmd, NULL, NULL, 0},
-	{"trimright",	StringTrimRCmd,	TclCompileBasic1Or2ArgCmd, NULL, NULL, 0},
+	{"tolower",	StringLowerCmd,	TclCompileStringToLowerCmd, NULL, NULL, 0},
+	{"toupper",	StringUpperCmd,	TclCompileStringToUpperCmd, NULL, NULL, 0},
+	{"totitle",	StringTitleCmd,	TclCompileStringToTitleCmd, NULL, NULL, 0},
+	{"trim",	StringTrimCmd,	TclCompileStringTrimCmd, NULL, NULL, 0},
+	{"trimleft",	StringTrimLCmd,	TclCompileStringTrimLCmd, NULL, NULL, 0},
+	{"trimright",	StringTrimRCmd,	TclCompileStringTrimRCmd, NULL, NULL, 0},
 	{"wordend",	StringEndCmd,	TclCompileBasic2ArgCmd, NULL, NULL, 0},
 	{"wordstart",	StringStartCmd,	TclCompileBasic2ArgCmd, NULL, NULL, 0},
 	{NULL, NULL, NULL, NULL, NULL, 0}
diff --git a/generic/tclCompCmds.c b/generic/tclCompCmds.c
index 323aa87..d1d7a80 100644
--- a/generic/tclCompCmds.c
+++ b/generic/tclCompCmds.c
@@ -278,7 +278,7 @@ TclCompileArraySetCmd(
 
     if (isDataValid && !isDataEven) {
 	PushStringLiteral(envPtr, "list must have an even number of elements");
-	PushStringLiteral(envPtr, "-errorCode {TCL ARGUMENT FORMAT}");
+	PushStringLiteral(envPtr, "-errorcode {TCL ARGUMENT FORMAT}");
 	TclEmitInstInt4(INST_RETURN_IMM, TCL_ERROR,		envPtr);
 	TclEmitInt4(		0,				envPtr);
 	goto done;
@@ -373,7 +373,7 @@ TclCompileArraySetCmd(
 	offsetFwd = CurrentOffset(envPtr);
 	TclEmitInstInt1(INST_JUMP_FALSE1, 0,			envPtr);
 	PushStringLiteral(envPtr, "list must have an even number of elements");
-	PushStringLiteral(envPtr, "-errorCode {TCL ARGUMENT FORMAT}");
+	PushStringLiteral(envPtr, "-errorcode {TCL ARGUMENT FORMAT}");
 	TclEmitInstInt4(INST_RETURN_IMM, TCL_ERROR,		envPtr);
 	TclEmitInt4(		0,				envPtr);
 	TclAdjustStackDepth(-1, envPtr);
@@ -690,6 +690,93 @@ TclCompileCatchCmd(
 /*
  *----------------------------------------------------------------------
  *
+ * TclCompileConcatCmd --
+ *
+ *	Procedure called to compile the "concat" command.
+ *
+ * Results:
+ *	Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
+ *	evaluation to runtime.
+ *
+ * Side effects:
+ *	Instructions are added to envPtr to execute the "concat" command at
+ *	runtime.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclCompileConcatCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Obj *objPtr, *listObj;
+    Tcl_Token *tokenPtr;
+    int i;
+
+    /* TODO: Consider compiling expansion case. */
+    if (parsePtr->numWords == 1) {
+	/*
+	 * [concat] without arguments just pushes an empty object.
+	 */
+
+	PushStringLiteral(envPtr, "");
+	return TCL_OK;
+    }
+
+    /*
+     * Test if all arguments are compile-time known. If they are, we can
+     * implement with a simple push.
+     */
+
+    listObj = Tcl_NewObj();
+    for (i = 1, tokenPtr = parsePtr->tokenPtr; i < parsePtr->numWords; i++) {
+	tokenPtr = TokenAfter(tokenPtr);
+	objPtr = Tcl_NewObj();
+	if (!TclWordKnownAtCompileTime(tokenPtr, objPtr)) {
+	    Tcl_DecrRefCount(objPtr);
+	    Tcl_DecrRefCount(listObj);
+	    listObj = NULL;
+	    break;
+	}
+	(void) Tcl_ListObjAppendElement(NULL, listObj, objPtr);
+    }
+    if (listObj != NULL) {
+	Tcl_Obj **objs;
+	const char *bytes;
+	int len;
+
+	Tcl_ListObjGetElements(NULL, listObj, &len, &objs);
+	objPtr = Tcl_ConcatObj(len, objs);
+	Tcl_DecrRefCount(listObj);
+	bytes = Tcl_GetStringFromObj(objPtr, &len);
+	PushLiteral(envPtr, bytes, len);
+	Tcl_DecrRefCount(objPtr);
+	return TCL_OK;
+    }
+
+    /*
+     * General case: runtime concat.
+     */
+
+    for (i = 1, tokenPtr = parsePtr->tokenPtr; i < parsePtr->numWords; i++) {
+	tokenPtr = TokenAfter(tokenPtr);
+	CompileWord(envPtr, tokenPtr, interp, i);
+    }
+
+    TclEmitInstInt4(	INST_CONCAT_STK, i-1,		envPtr);
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * TclCompileContinueCmd --
  *
  *	Procedure called to compile the "continue" command.
@@ -1678,7 +1765,7 @@ TclCompileDictAppendCmd(
 	tokenPtr = TokenAfter(tokenPtr);
     }
     if (parsePtr->numWords > 4) {
-	TclEmitInstInt1(INST_CONCAT1, parsePtr->numWords-3, envPtr);
+	TclEmitInstInt1(INST_STR_CONCAT1, parsePtr->numWords-3, envPtr);
     }
 
     /*
@@ -3011,7 +3098,7 @@ TclCompileFormatCmd(
 	 * Do the concatenation, which produces the result.
 	 */
 
-	TclEmitInstInt1(INST_CONCAT1, i, envPtr);
+	TclEmitInstInt1(INST_STR_CONCAT1, i, envPtr);
     } else {
 	/*
 	 * EVIL HACK! Force there to be a string representation in the case
diff --git a/generic/tclCompCmdsGR.c b/generic/tclCompCmdsGR.c
index b7c89df..b3e273f 100644
--- a/generic/tclCompCmdsGR.c
+++ b/generic/tclCompCmdsGR.c
@@ -28,6 +28,58 @@ static void		CompileReturnInternal(CompileEnv *envPtr,
 static int		IndexTailVarIfKnown(Tcl_Interp *interp,
 			    Tcl_Token *varTokenPtr, CompileEnv *envPtr);
 
+#define INDEX_END	(-2)
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetIndexFromToken --
+ *
+ *	Parse a token and get the encoded version of the index (as understood
+ *	by TEBC), assuming it is at all knowable at compile time. Only handles
+ *	indices that are integers or 'end' or 'end-integer'.
+ *
+ * Returns:
+ *	TCL_OK if parsing succeeded, and TCL_ERROR if it failed.
+ *
+ * Side effects:
+ *	Sets *index to the index value if successful.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static inline int
+GetIndexFromToken(
+    Tcl_Token *tokenPtr,
+    int *index)
+{
+    Tcl_Obj *tmpObj = Tcl_NewObj();
+    int result, idx;
+
+    if (!TclWordKnownAtCompileTime(tokenPtr, tmpObj)) {
+	Tcl_DecrRefCount(tmpObj);
+	return TCL_ERROR;
+    }
+
+    result = TclGetIntFromObj(NULL, tmpObj, &idx);
+    if (result == TCL_OK) {
+	if (idx < 0) {
+	    result = TCL_ERROR;
+	}
+    } else {
+	result = TclGetIntForIndexM(NULL, tmpObj, INDEX_END, &idx);
+	if (result == TCL_OK && idx > INDEX_END) {
+	    result = TCL_ERROR;
+	}
+    }
+    Tcl_DecrRefCount(tmpObj);
+
+    if (result == TCL_OK) {
+	*index = idx;
+    }
+
+    return result;
+}
 
 /*
  *----------------------------------------------------------------------
@@ -1029,7 +1081,7 @@ TclCompileLassignCmd(
      */
 
     TclEmitInstInt4(		INST_LIST_RANGE_IMM, idx,	envPtr);
-    TclEmitInt4(		-2 /* == "end" */,		envPtr);
+    TclEmitInt4(			INDEX_END,		envPtr);
 
     return TCL_OK;
 }
@@ -1062,7 +1114,7 @@ TclCompileLindexCmd(
     CompileEnv *envPtr)		/* Holds resulting instructions. */
 {
     Tcl_Token *idxTokenPtr, *valTokenPtr;
-    int i, numWords = parsePtr->numWords;
+    int i, idx, numWords = parsePtr->numWords;
     DefineLineInformation;	/* TIP #280 */
 
     /*
@@ -1080,46 +1132,28 @@ TclCompileLindexCmd(
     }
 
     idxTokenPtr = TokenAfter(valTokenPtr);
-    if (idxTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
-	Tcl_Obj *tmpObj;
-	int idx, result;
-
-	tmpObj = Tcl_NewStringObj(idxTokenPtr[1].start, idxTokenPtr[1].size);
-	result = TclGetIntFromObj(NULL, tmpObj, &idx);
-	if (result == TCL_OK) {
-	    if (idx < 0) {
-		result = TCL_ERROR;
-	    }
-	} else {
-	    result = TclGetIntForIndexM(NULL, tmpObj, -2, &idx);
-	    if (result == TCL_OK && idx > -2) {
-		result = TCL_ERROR;
-	    }
-	}
-	TclDecrRefCount(tmpObj);
-
-	if (result == TCL_OK) {
-	    /*
-	     * All checks have been completed, and we have exactly one of
-	     * these constructs:
-	     *	 lindex <arbitraryValue> <posInt>
-	     *	 lindex <arbitraryValue> end-<posInt>
-	     * This is best compiled as a push of the arbitrary value followed
-	     * by an "immediate lindex" which is the most efficient variety.
-	     */
-
-	    CompileWord(envPtr, valTokenPtr, interp, 1);
-	    TclEmitInstInt4(	INST_LIST_INDEX_IMM, idx,	envPtr);
-	    return TCL_OK;
-	}
-
+    if (GetIndexFromToken(idxTokenPtr, &idx) == TCL_OK) {
 	/*
-	 * If the conversion failed or the value was negative, we just keep on
-	 * going with the more complex compilation.
+	 * All checks have been completed, and we have exactly one of these
+	 * constructs:
+	 *	 lindex <arbitraryValue> <posInt>
+	 *	 lindex <arbitraryValue> end-<posInt>
+	 * This is best compiled as a push of the arbitrary value followed by
+	 * an "immediate lindex" which is the most efficient variety.
 	 */
+
+	CompileWord(envPtr, valTokenPtr, interp, 1);
+	TclEmitInstInt4(	INST_LIST_INDEX_IMM, idx,	envPtr);
+	return TCL_OK;
     }
 
     /*
+     * If the value was not known at compile time, the conversion failed or
+     * the value was negative, we just keep on going with the more complex
+     * compilation.
+     */
+
+    /*
      * Push the operands onto the stack.
      */
 
@@ -1265,7 +1299,7 @@ TclCompileListCmd(
 
     if (concat && numWords == 2) {
 	TclEmitInstInt4(	INST_LIST_RANGE_IMM, 0,	envPtr);
-	TclEmitInt4(			-2,		envPtr);
+	TclEmitInt4(			INDEX_END,	envPtr);
     }
     return TCL_OK;
 }
@@ -1332,8 +1366,7 @@ TclCompileLrangeCmd(
 {
     Tcl_Token *tokenPtr, *listTokenPtr;
     DefineLineInformation;	/* TIP #280 */
-    Tcl_Obj *tmpObj;
-    int idx1, idx2, result;
+    int idx1, idx2;
 
     if (parsePtr->numWords != 4) {
 	return TCL_ERROR;
@@ -1341,56 +1374,18 @@ TclCompileLrangeCmd(
     listTokenPtr = TokenAfter(parsePtr->tokenPtr);
 
     /*
-     * Parse the first index. Will only compile if it is constant and not an
+     * Parse the indices. Will only compile if both are constants and not an
      * _integer_ less than zero (since we reserve negative indices here for
-     * end-relative indexing).
+     * end-relative indexing) or an end-based index greater than 'end' itself.
      */
 
     tokenPtr = TokenAfter(listTokenPtr);
-    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
-	return TCL_ERROR;
-    }
-    tmpObj = Tcl_NewStringObj(tokenPtr[1].start, tokenPtr[1].size);
-    result = TclGetIntFromObj(NULL, tmpObj, &idx1);
-    if (result == TCL_OK) {
-	if (idx1 < 0) {
-	    result = TCL_ERROR;
-	}
-    } else {
-	result = TclGetIntForIndexM(NULL, tmpObj, -2, &idx1);
-	if (result == TCL_OK && idx1 > -2) {
-	    result = TCL_ERROR;
-	}
-    }
-    TclDecrRefCount(tmpObj);
-    if (result != TCL_OK) {
+    if (GetIndexFromToken(tokenPtr, &idx1) != TCL_OK) {
 	return TCL_ERROR;
     }
 
-    /*
-     * Parse the second index. Will only compile if it is constant and not an
-     * _integer_ less than zero (since we reserve negative indices here for
-     * end-relative indexing).
-     */
-
     tokenPtr = TokenAfter(tokenPtr);
-    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
-	return TCL_ERROR;
-    }
-    tmpObj = Tcl_NewStringObj(tokenPtr[1].start, tokenPtr[1].size);
-    result = TclGetIntFromObj(NULL, tmpObj, &idx2);
-    if (result == TCL_OK) {
-	if (idx2 < 0) {
-	    result = TCL_ERROR;
-	}
-    } else {
-	result = TclGetIntForIndexM(NULL, tmpObj, -2, &idx2);
-	if (result == TCL_OK && idx2 > -2) {
-	    result = TCL_ERROR;
-	}
-    }
-    TclDecrRefCount(tmpObj);
-    if (result != TCL_OK) {
+    if (GetIndexFromToken(tokenPtr, &idx2) != TCL_OK) {
 	return TCL_ERROR;
     }
 
@@ -1409,19 +1404,16 @@ TclCompileLrangeCmd(
 /*
  *----------------------------------------------------------------------
  *
- * TclCompileLreplaceCmd --
+ * TclCompileLinsertCmd --
  *
- *	How to compile the "lreplace" command. We only bother with the case
- *	where there are no elements to insert and where both the 'first' and
- *	'last' arguments are constant and one can be deterined to be at the
- *	end of the list. (This is the case that could also be written with
- *	"lrange".)
+ *	How to compile the "linsert" command. We only bother with the case
+ *	where the index is constant.
  *
  *----------------------------------------------------------------------
  */
 
 int
-TclCompileLreplaceCmd(
+TclCompileLinsertCmd(
     Tcl_Interp *interp,		/* Tcl interpreter for context. */
     Tcl_Parse *parsePtr,	/* Points to a parse structure for the
 				 * command. */
@@ -1431,101 +1423,272 @@ TclCompileLreplaceCmd(
 {
     Tcl_Token *tokenPtr, *listTokenPtr;
     DefineLineInformation;	/* TIP #280 */
-    Tcl_Obj *tmpObj;
-    int idx1, idx2, result, guaranteedDropAll = 0;
+    int idx, i;
 
-    if (parsePtr->numWords != 4) {
+    if (parsePtr->numWords < 3) {
 	return TCL_ERROR;
     }
     listTokenPtr = TokenAfter(parsePtr->tokenPtr);
 
     /*
-     * Parse the first index. Will only compile if it is constant and not an
+     * Parse the index. Will only compile if it is constant and not an
      * _integer_ less than zero (since we reserve negative indices here for
-     * end-relative indexing).
+     * end-relative indexing) or an end-based index greater than 'end' itself.
      */
 
     tokenPtr = TokenAfter(listTokenPtr);
-    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
+    if (GetIndexFromToken(tokenPtr, &idx) != TCL_OK) {
 	return TCL_ERROR;
     }
-    tmpObj = Tcl_NewStringObj(tokenPtr[1].start, tokenPtr[1].size);
-    result = TclGetIntFromObj(NULL, tmpObj, &idx1);
-    if (result == TCL_OK) {
-	if (idx1 < 0) {
-	    result = TCL_ERROR;
-	}
+
+    /*
+     * There are four main cases. If there are no values to insert, this is
+     * just a confirm-listiness check. If the index is '0', this is a prepend.
+     * If the index is 'end' (== INDEX_END), this is an append. Otherwise,
+     * this is a splice (== split, insert values as list, concat-3).
+     */
+
+    CompileWord(envPtr, listTokenPtr, interp, 1);
+    if (parsePtr->numWords == 3) {
+	TclEmitInstInt4(	INST_LIST_RANGE_IMM, 0,		envPtr);
+	TclEmitInt4(			INDEX_END,		envPtr);
+	return TCL_OK;
+    }
+
+    for (i=3 ; i<parsePtr->numWords ; i++) {
+	tokenPtr = TokenAfter(tokenPtr);
+	CompileWord(envPtr, tokenPtr, interp, i);
+    }
+    TclEmitInstInt4(		INST_LIST, i-3,			envPtr);
+
+    if (idx == 0 /*start*/) {
+	TclEmitInstInt4(	INST_REVERSE, 2,		envPtr);
+	TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+    } else if (idx == INDEX_END /*end*/) {
+	TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
     } else {
-	result = TclGetIntForIndexM(NULL, tmpObj, -2, &idx1);
-	if (result == TCL_OK && idx1 > -2) {
-	    result = TCL_ERROR;
+	if (idx < 0) {
+	    idx++;
 	}
+	TclEmitInstInt4(	INST_OVER, 1,			envPtr);
+	TclEmitInstInt4(	INST_LIST_RANGE_IMM, 0,		envPtr);
+	TclEmitInt4(			idx-1,			envPtr);
+	TclEmitInstInt4(	INST_REVERSE, 3,		envPtr);
+	TclEmitInstInt4(	INST_LIST_RANGE_IMM, idx,	envPtr);
+	TclEmitInt4(			INDEX_END,		envPtr);
+	TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+	TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
     }
-    TclDecrRefCount(tmpObj);
-    if (result != TCL_OK) {
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclCompileLreplaceCmd --
+ *
+ *	How to compile the "lreplace" command. We only bother with the case
+ *	where the indices are constant.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclCompileLreplaceCmd(
+    Tcl_Interp *interp,		/* Tcl interpreter for context. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the
+				 * command. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds the resulting instructions. */
+{
+    Tcl_Token *tokenPtr, *listTokenPtr;
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Obj *tmpObj;
+    int idx1, idx2, i, offset;
+
+    if (parsePtr->numWords < 4) {
 	return TCL_ERROR;
     }
+    listTokenPtr = TokenAfter(parsePtr->tokenPtr);
 
     /*
-     * Parse the second index. Will only compile if it is constant and not an
+     * Parse the indices. Will only compile if both are constants and not an
      * _integer_ less than zero (since we reserve negative indices here for
-     * end-relative indexing).
+     * end-relative indexing) or an end-based index greater than 'end' itself.
      */
 
-    tokenPtr = TokenAfter(tokenPtr);
-    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
+    tokenPtr = TokenAfter(listTokenPtr);
+    if (GetIndexFromToken(tokenPtr, &idx1) != TCL_OK) {
 	return TCL_ERROR;
     }
-    tmpObj = Tcl_NewStringObj(tokenPtr[1].start, tokenPtr[1].size);
-    result = TclGetIntFromObj(NULL, tmpObj, &idx2);
-    if (result == TCL_OK) {
-	if (idx2 < 0) {
-	    result = TCL_ERROR;
-	}
-    } else {
-	result = TclGetIntForIndexM(NULL, tmpObj, -2, &idx2);
-	if (result == TCL_OK && idx2 > -2) {
-	    result = TCL_ERROR;
-	}
-    }
-    TclDecrRefCount(tmpObj);
-    if (result != TCL_OK) {
+
+    tokenPtr = TokenAfter(tokenPtr);
+    if (GetIndexFromToken(tokenPtr, &idx2) != TCL_OK) {
 	return TCL_ERROR;
     }
 
     /*
-     * Sanity check: can only issue when we're removing a range at one or
-     * other end of the list. If we're at one end or the other, convert the
-     * indices into the equivalent for an [lrange].
+     * Work out what this [lreplace] is actually doing.
      */
 
+    tmpObj = NULL;
+    CompileWord(envPtr, listTokenPtr, interp, 1);
+    if (parsePtr->numWords == 4) {
+	if (idx1 == 0) {
+	    if (idx2 == INDEX_END) {
+		goto dropAll;
+	    }
+	    idx1 = idx2 + 1;
+	    idx2 = INDEX_END;
+	    goto dropEnd;
+	} else if (idx2 == INDEX_END) {
+	    idx2 = idx1 - 1;
+	    idx1 = 0;
+	    goto dropEnd;
+	} else {
+	    if (idx1 > 0) {
+		tmpObj = Tcl_NewIntObj(idx1);
+		Tcl_IncrRefCount(tmpObj);
+	    }
+	    goto dropRange;
+	}
+    }
+
+    tokenPtr = TokenAfter(tokenPtr);
+    for (i=4 ; i<parsePtr->numWords ; i++) {
+	CompileWord(envPtr, tokenPtr, interp, i);
+	tokenPtr = TokenAfter(tokenPtr);
+    }
+    TclEmitInstInt4(		INST_LIST, i - 4,		envPtr);
+    TclEmitInstInt4(		INST_REVERSE, 2,		envPtr);
     if (idx1 == 0) {
-	if (idx2 == -2) {
-	    guaranteedDropAll = 1;
+	if (idx2 == INDEX_END) {
+	    goto replaceAll;
 	}
 	idx1 = idx2 + 1;
-	idx2 = -2;
-    } else if (idx2 == -2) {
+	idx2 = INDEX_END;
+	goto replaceHead;
+    } else if (idx2 == INDEX_END) {
 	idx2 = idx1 - 1;
 	idx1 = 0;
+	goto replaceTail;
     } else {
-	return TCL_ERROR;
+	if (idx1 > 0 && idx2 > 0 && idx2 < idx1) {
+	    idx2 = idx1 - 1;
+	} else if (idx1 < 0 && idx2 < 0 && idx2 < idx1) {
+	    idx2 = idx1 - 1;
+	}
+	if (idx1 > 0) {
+	    tmpObj = Tcl_NewIntObj(idx1);
+	    Tcl_IncrRefCount(tmpObj);
+	}
+	goto replaceRange;
     }
 
     /*
-     * Issue instructions. It's not safe to skip doing the LIST_RANGE, as
-     * we've not proved that the 'list' argument is really a list. Not that it
-     * is worth trying to do that given current knowledge.
+     * Issue instructions to perform the operations relating to configurations
+     * that just drop. The only argument pushed on the stack is the list to
+     * operate on.
      */
 
-    CompileWord(envPtr, listTokenPtr, interp, 1);
-    if (guaranteedDropAll) {
+  dropAll:
+    TclEmitOpcode(		INST_LIST_LENGTH,		envPtr);
+    TclEmitOpcode(		INST_POP,			envPtr);
+    PushStringLiteral(envPtr,	"");
+    goto done;
+
+  dropEnd:
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, idx1,	envPtr);
+    TclEmitInt4(			idx2,			envPtr);
+    goto done;
+
+  dropRange:
+    if (tmpObj != NULL) {
+	TclEmitOpcode(		INST_DUP,			envPtr);
 	TclEmitOpcode(		INST_LIST_LENGTH,		envPtr);
-	TclEmitOpcode(		INST_POP,			envPtr);
-	PushStringLiteral(envPtr, "");
-    } else {
-	TclEmitInstInt4(	INST_LIST_RANGE_IMM, idx1,	envPtr);
-	TclEmitInt4(		idx2,				envPtr);
+	TclEmitPush(TclAddLiteralObj(envPtr, tmpObj, NULL),	envPtr);
+	TclEmitOpcode(		INST_GT,			envPtr);
+	offset = CurrentOffset(envPtr);
+	TclEmitInstInt1(	INST_JUMP_TRUE1, 0,		envPtr);
+	TclEmitPush(TclAddLiteralObj(envPtr, Tcl_ObjPrintf(
+		"list doesn't contain element %d", idx1), NULL), envPtr);
+	CompileReturnInternal(envPtr, INST_RETURN_IMM, TCL_ERROR, 0,
+		Tcl_ObjPrintf("-errorcode {TCL OPERATION LREPLACE BADIDX}"));
+	TclStoreInt1AtPtr(CurrentOffset(envPtr) - offset,
+		envPtr->codeStart + offset + 1);
+	TclAdjustStackDepth(-1, envPtr);
+    }
+    TclEmitOpcode(		INST_DUP,			envPtr);
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, 0,		envPtr);
+    TclEmitInt4(			idx1 - 1,		envPtr);
+    TclEmitInstInt4(		INST_REVERSE, 2,		envPtr);
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, idx2 + 1,	envPtr);
+    TclEmitInt4(			INDEX_END,		envPtr);
+    TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+    goto done;
+
+    /*
+     * Issue instructions to perform the operations relating to configurations
+     * that do real replacement. All arguments are pushed and assembled into a
+     * pair: the list of values to replace with, and the list to do the
+     * surgery on.
+     */
+
+  replaceAll:
+    TclEmitOpcode(		INST_LIST_LENGTH,		envPtr);
+    TclEmitOpcode(		INST_POP,			envPtr);
+    goto done;
+
+  replaceHead:
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, idx1,	envPtr);
+    TclEmitInt4(			idx2,			envPtr);
+    TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+    goto done;
+
+  replaceTail:
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, idx1,	envPtr);
+    TclEmitInt4(			idx2,			envPtr);
+    TclEmitInstInt4(		INST_REVERSE, 2,		envPtr);
+    TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+    goto done;
+
+  replaceRange:
+    if (tmpObj != NULL) {
+	TclEmitOpcode(		INST_DUP,			envPtr);
+	TclEmitOpcode(		INST_LIST_LENGTH,		envPtr);
+	TclEmitPush(TclAddLiteralObj(envPtr, tmpObj, NULL),	envPtr);
+	TclEmitOpcode(		INST_GT,			envPtr);
+	offset = CurrentOffset(envPtr);
+	TclEmitInstInt1(	INST_JUMP_TRUE1, 0,		envPtr);
+	TclEmitPush(TclAddLiteralObj(envPtr, Tcl_ObjPrintf(
+		"list doesn't contain element %d", idx1), NULL), envPtr);
+	CompileReturnInternal(envPtr, INST_RETURN_IMM, TCL_ERROR, 0,
+		Tcl_ObjPrintf("-errorcode {TCL OPERATION LREPLACE BADIDX}"));
+	TclStoreInt1AtPtr(CurrentOffset(envPtr) - offset,
+		envPtr->codeStart + offset + 1);
+	TclAdjustStackDepth(-1, envPtr);
+    }
+    TclEmitOpcode(		INST_DUP,			envPtr);
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, 0,		envPtr);
+    TclEmitInt4(			idx1 - 1,		envPtr);
+    TclEmitInstInt4(		INST_REVERSE, 2,		envPtr);
+    TclEmitInstInt4(		INST_LIST_RANGE_IMM, idx2 + 1,	envPtr);
+    TclEmitInt4(			INDEX_END,		envPtr);
+    TclEmitInstInt4(		INST_REVERSE, 3,		envPtr);
+    TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+    TclEmitInstInt4(		INST_REVERSE, 2,		envPtr);
+    TclEmitOpcode(		INST_LIST_CONCAT,		envPtr);
+    goto done;
+
+    /*
+     * Clean up the allocated memory.
+     */
+
+  done:
+    if (tmpObj != NULL) {
+	Tcl_DecrRefCount(tmpObj);
     }
     return TCL_OK;
 }
@@ -1793,6 +1956,28 @@ TclCompileNamespaceCodeCmd(
 }
 
 int
+TclCompileNamespaceOriginCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    Tcl_Token *tokenPtr;
+    DefineLineInformation;	/* TIP #280 */
+
+    if (parsePtr->numWords != 2) {
+	return TCL_ERROR;
+    }
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+
+    CompileWord(envPtr,	tokenPtr,			interp, 1);
+    TclEmitOpcode(	INST_ORIGIN_COMMAND,		envPtr);
+    return TCL_OK;
+}
+
+int
 TclCompileNamespaceQualifiersCmd(
     Tcl_Interp *interp,		/* Used for error reporting. */
     Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
@@ -2854,6 +3039,66 @@ IndexTailVarIfKnown(
     return localIndex;
 }
 
+/*
+ * ----------------------------------------------------------------------
+ *
+ * TclCompileObjectNextCmd, TclCompileObjectSelfCmd --
+ *
+ *	Compilations of the TclOO utility commands [next] and [self].
+ *
+ * ----------------------------------------------------------------------
+ */
+
+int
+TclCompileObjectNextCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr = parsePtr->tokenPtr;
+    int i;
+
+    if (parsePtr->numWords > 255) {
+	return TCL_ERROR;
+    }
+
+    for (i=0 ; i<parsePtr->numWords ; i++) {
+	CompileWord(envPtr, tokenPtr, interp, i);
+	tokenPtr = TokenAfter(tokenPtr);
+    }
+    TclEmitInstInt1(	INST_TCLOO_NEXT, i,		envPtr);
+    return TCL_OK;
+}
+
+int
+TclCompileObjectNextToCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr = parsePtr->tokenPtr;
+    int i;
+
+    if (parsePtr->numWords < 2 || parsePtr->numWords > 255) {
+	return TCL_ERROR;
+    }
+
+    for (i=0 ; i<parsePtr->numWords ; i++) {
+	CompileWord(envPtr, tokenPtr, interp, i);
+	tokenPtr = TokenAfter(tokenPtr);
+    }
+    TclEmitInstInt1(	INST_TCLOO_NEXT_CLASS, i,	envPtr);
+    return TCL_OK;
+}
+
 int
 TclCompileObjectSelfCmd(
     Tcl_Interp *interp,		/* Used for error reporting. */
diff --git a/generic/tclCompCmdsSZ.c b/generic/tclCompCmdsSZ.c
index 3e4a55a..4b14f24 100644
--- a/generic/tclCompCmdsSZ.c
+++ b/generic/tclCompCmdsSZ.c
@@ -17,6 +17,7 @@
 
 #include "tclInt.h"
 #include "tclCompile.h"
+#include "tclStringTrim.h"
 
 /*
  * Prototypes for procedures defined later in this file:
@@ -101,6 +102,59 @@ const AuxDataType tclJumptableInfoType = {
     if ((idx)<256) {OP1(STORE_SCALAR1,(idx));} else {OP4(STORE_SCALAR4,(idx));}
 #define INVOKE(name) \
     TclEmitInvoke(envPtr,INST_##name)
+
+#define INDEX_END	(-2)
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetIndexFromToken --
+ *
+ *	Parse a token and get the encoded version of the index (as understood
+ *	by TEBC), assuming it is at all knowable at compile time. Only handles
+ *	indices that are integers or 'end' or 'end-integer'.
+ *
+ * Returns:
+ *	TCL_OK if parsing succeeded, and TCL_ERROR if it failed.
+ *
+ * Side effects:
+ *	Sets *index to the index value if successful.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static inline int
+GetIndexFromToken(
+    Tcl_Token *tokenPtr,
+    int *index)
+{
+    Tcl_Obj *tmpObj = Tcl_NewObj();
+    int result, idx;
+
+    if (!TclWordKnownAtCompileTime(tokenPtr, tmpObj)) {
+	Tcl_DecrRefCount(tmpObj);
+	return TCL_ERROR;
+    }
+
+    result = TclGetIntFromObj(NULL, tmpObj, &idx);
+    if (result == TCL_OK) {
+	if (idx < 0) {
+	    result = TCL_ERROR;
+	}
+    } else {
+	result = TclGetIntForIndexM(NULL, tmpObj, INDEX_END, &idx);
+	if (result == TCL_OK && idx > INDEX_END) {
+	    result = TCL_ERROR;
+	}
+    }
+    Tcl_DecrRefCount(tmpObj);
+
+    if (result == TCL_OK) {
+	*index = idx;
+    }
+
+    return result;
+}
 
 /*
  *----------------------------------------------------------------------
@@ -565,8 +619,7 @@ TclCompileStringRangeCmd(
 {
     DefineLineInformation;	/* TIP #280 */
     Tcl_Token *stringTokenPtr, *fromTokenPtr, *toTokenPtr;
-    Tcl_Obj *tmpObj;
-    int idx1, idx2, result;
+    int idx1, idx2;
 
     if (parsePtr->numWords != 4) {
 	return TCL_ERROR;
@@ -576,50 +629,13 @@ TclCompileStringRangeCmd(
     toTokenPtr = TokenAfter(fromTokenPtr);
 
     /*
-     * Parse the first index. Will only compile if it is constant and not an
-     * _integer_ less than zero (since we reserve negative indices here for
-     * end-relative indexing).
+     * Parse the two indices.
      */
 
-    tmpObj = Tcl_NewObj();
-    result = TCL_ERROR;
-    if (TclWordKnownAtCompileTime(fromTokenPtr, tmpObj)) {
-	if (TclGetIntFromObj(NULL, tmpObj, &idx1) == TCL_OK) {
-	    if (idx1 >= 0) {
-		result = TCL_OK;
-	    }
-	} else if (TclGetIntForIndexM(NULL, tmpObj, -2, &idx1) == TCL_OK) {
-	    if (idx1 <= -2) {
-		result = TCL_OK;
-	    }
-	}
-    }
-    TclDecrRefCount(tmpObj);
-    if (result != TCL_OK) {
+    if (GetIndexFromToken(fromTokenPtr, &idx1) != TCL_OK) {
 	goto nonConstantIndices;
     }
-
-    /*
-     * Parse the second index. Will only compile if it is constant and not an
-     * _integer_ less than zero (since we reserve negative indices here for
-     * end-relative indexing).
-     */
-
-    tmpObj = Tcl_NewObj();
-    result = TCL_ERROR;
-    if (TclWordKnownAtCompileTime(toTokenPtr, tmpObj)) {
-	if (TclGetIntFromObj(NULL, tmpObj, &idx2) == TCL_OK) {
-	    if (idx2 >= 0) {
-		result = TCL_OK;
-	    }
-	} else if (TclGetIntForIndexM(NULL, tmpObj, -2, &idx2) == TCL_OK) {
-	    if (idx2 <= -2) {
-		result = TCL_OK;
-	    }
-	}
-    }
-    TclDecrRefCount(tmpObj);
-    if (result != TCL_OK) {
+    if (GetIndexFromToken(toTokenPtr, &idx2) != TCL_OK) {
 	goto nonConstantIndices;
     }
 
@@ -642,6 +658,285 @@ TclCompileStringRangeCmd(
     OP(			STR_RANGE);
     return TCL_OK;
 }
+
+int
+TclCompileStringReplaceCmd(
+    Tcl_Interp *interp,		/* Tcl interpreter for context. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the
+				 * command. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds the resulting instructions. */
+{
+    Tcl_Token *tokenPtr, *valueTokenPtr, *replacementTokenPtr = NULL;
+    DefineLineInformation;	/* TIP #280 */
+    int idx1, idx2;
+
+    if (parsePtr->numWords < 4 || parsePtr->numWords > 5) {
+	return TCL_ERROR;
+    }
+    valueTokenPtr = TokenAfter(parsePtr->tokenPtr);
+    if (parsePtr->numWords == 5) {
+	tokenPtr = TokenAfter(valueTokenPtr);
+	tokenPtr = TokenAfter(tokenPtr);
+	replacementTokenPtr = TokenAfter(tokenPtr);
+    }
+
+    /*
+     * Parse the indices. Will only compile special cases if both are
+     * constants and not an _integer_ less than zero (since we reserve
+     * negative indices here for end-relative indexing) or an end-based index
+     * greater than 'end' itself.
+     */
+
+    tokenPtr = TokenAfter(valueTokenPtr);
+    if (GetIndexFromToken(tokenPtr, &idx1) != TCL_OK) {
+	goto genericReplace;
+    }
+
+    tokenPtr = TokenAfter(tokenPtr);
+    if (GetIndexFromToken(tokenPtr, &idx2) != TCL_OK) {
+	goto genericReplace;
+    }
+
+    /*
+     * We handle these replacements specially: first character (where
+     * idx1=idx2=0) and last character (where idx1=idx2=INDEX_END). Anything
+     * else and the semantics get rather screwy.
+     */
+
+    if (idx1 == 0 && idx2 == 0) {
+	int notEq, end;
+
+	/*
+	 * Just working with the first character.
+	 */
+
+	CompileWord(envPtr, valueTokenPtr, interp, 1);
+	if (replacementTokenPtr == NULL) {
+	    /* Drop first */
+	    OP44(	STR_RANGE_IMM, 1, INDEX_END);
+	    return TCL_OK;
+	}
+	/* Replace first */
+	CompileWord(envPtr, replacementTokenPtr, interp, 4);
+	OP4(		OVER, 1);
+	PUSH(		"");
+	OP(		STR_EQ);
+	JUMP1(		JUMP_FALSE, notEq);
+	OP(		POP);
+	JUMP1(		JUMP, end);
+	FIXJUMP1(notEq);
+	TclAdjustStackDepth(1, envPtr);
+	OP4(		REVERSE, 2);
+	OP44(		STR_RANGE_IMM, 1, INDEX_END);
+	OP1(		STR_CONCAT1, 2);
+	FIXJUMP1(end);
+	return TCL_OK;
+
+    } else if (idx1 == INDEX_END && idx2 == INDEX_END) {
+	int notEq, end;
+
+	/*
+	 * Just working with the last character.
+	 */
+
+	CompileWord(envPtr, valueTokenPtr, interp, 1);
+	if (replacementTokenPtr == NULL) {
+	    /* Drop last */
+	    OP44(	STR_RANGE_IMM, 0, INDEX_END-1);
+	    return TCL_OK;
+	}
+	/* Replace last */
+	CompileWord(envPtr, replacementTokenPtr, interp, 4);
+	OP4(		OVER, 1);
+	PUSH(		"");
+	OP(		STR_EQ);
+	JUMP1(		JUMP_FALSE, notEq);
+	OP(		POP);
+	JUMP1(		JUMP, end);
+	FIXJUMP1(notEq);
+	TclAdjustStackDepth(1, envPtr);
+	OP4(		REVERSE, 2);
+	OP44(		STR_RANGE_IMM, 0, INDEX_END-1);
+	OP4(		REVERSE, 2);
+	OP1(		STR_CONCAT1, 2);
+	FIXJUMP1(end);
+	return TCL_OK;
+
+    } else {
+	/*
+	 * Need to process indices at runtime. This could be because the
+	 * indices are not constants, or because we need to resolve them to
+	 * absolute indices to work out if a replacement is going to happen.
+	 * In any case, to runtime it is.
+	 */
+
+    genericReplace:
+	CompileWord(envPtr, valueTokenPtr, interp, 1);
+	tokenPtr = TokenAfter(valueTokenPtr);
+	CompileWord(envPtr, tokenPtr, interp, 2);
+	tokenPtr = TokenAfter(tokenPtr);
+	CompileWord(envPtr, tokenPtr, interp, 3);
+	if (replacementTokenPtr != NULL) {
+	    CompileWord(envPtr, replacementTokenPtr, interp, 4);
+	} else {
+	    PUSH(	"");
+	}
+	OP(		STR_REPLACE);
+	return TCL_OK;
+    }
+}
+
+int
+TclCompileStringTrimLCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr;
+
+    if (parsePtr->numWords != 2 && parsePtr->numWords != 3) {
+	return TCL_ERROR;
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    CompileWord(envPtr, tokenPtr,			interp, 1);
+    if (parsePtr->numWords == 3) {
+	tokenPtr = TokenAfter(tokenPtr);
+	CompileWord(envPtr, tokenPtr,			interp, 2);
+    } else {
+	PushLiteral(envPtr, tclDefaultTrimSet, strlen(tclDefaultTrimSet));
+    }
+    OP(			STR_TRIM_LEFT);
+    return TCL_OK;
+}
+
+int
+TclCompileStringTrimRCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr;
+
+    if (parsePtr->numWords != 2 && parsePtr->numWords != 3) {
+	return TCL_ERROR;
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    CompileWord(envPtr, tokenPtr,			interp, 1);
+    if (parsePtr->numWords == 3) {
+	tokenPtr = TokenAfter(tokenPtr);
+	CompileWord(envPtr, tokenPtr,			interp, 2);
+    } else {
+	PushLiteral(envPtr, tclDefaultTrimSet, strlen(tclDefaultTrimSet));
+    }
+    OP(			STR_TRIM_RIGHT);
+    return TCL_OK;
+}
+
+int
+TclCompileStringTrimCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr;
+
+    if (parsePtr->numWords != 2 && parsePtr->numWords != 3) {
+	return TCL_ERROR;
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    CompileWord(envPtr, tokenPtr,			interp, 1);
+    if (parsePtr->numWords == 3) {
+	tokenPtr = TokenAfter(tokenPtr);
+	CompileWord(envPtr, tokenPtr,			interp, 2);
+    } else {
+	PushLiteral(envPtr, tclDefaultTrimSet, strlen(tclDefaultTrimSet));
+    }
+    OP(			STR_TRIM);
+    return TCL_OK;
+}
+
+int
+TclCompileStringToUpperCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr;
+
+    if (parsePtr->numWords != 2) {
+	return TclCompileBasic1To3ArgCmd(interp, parsePtr, cmdPtr, envPtr);
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    CompileWord(envPtr, tokenPtr,			interp, 1);
+    OP(			STR_UPPER);
+    return TCL_OK;
+}
+
+int
+TclCompileStringToLowerCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr;
+
+    if (parsePtr->numWords != 2) {
+	return TclCompileBasic1To3ArgCmd(interp, parsePtr, cmdPtr, envPtr);
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    CompileWord(envPtr, tokenPtr,			interp, 1);
+    OP(			STR_LOWER);
+    return TCL_OK;
+}
+
+int
+TclCompileStringToTitleCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr;
+
+    if (parsePtr->numWords != 2) {
+	return TclCompileBasic1To3ArgCmd(interp, parsePtr, cmdPtr, envPtr);
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    CompileWord(envPtr, tokenPtr,			interp, 1);
+    OP(			STR_TITLE);
+    return TCL_OK;
+}
 
 /*
  *----------------------------------------------------------------------
@@ -752,7 +1047,7 @@ TclSubstCompile(
     /*
      * Tricky point! If the first token does not result in a *guaranteed* push
      * of a Tcl_Obj on the stack, we must push an empty object. Otherwise it
-     * is possible to get to an INST_CONCAT1 or INST_DONE without enough
+     * is possible to get to an INST_STR_CONCAT1 or INST_DONE without enough
      * values on the stack, resulting in a crash. Thanks to Joe Mistachkin for
      * identifying a script that could trigger this case.
      */
@@ -817,11 +1112,11 @@ TclSubstCompile(
 	}
 
 	while (count > 255) {
-	    OP1(		CONCAT1, 255);
+	    OP1(		STR_CONCAT1, 255);
 	    count -= 254;
 	}
 	if (count > 1) {
-	    OP1(		CONCAT1, count);
+	    OP1(		STR_CONCAT1, count);
 	    count = 1;
 	}
 
@@ -941,7 +1236,7 @@ TclSubstCompile(
 		    (int) (CurrentOffset(envPtr) - okFixup.codeOffset));
 	}
 	if (count > 1) {
-	    OP1(CONCAT1, count);
+	    OP1(STR_CONCAT1, count);
 	    count = 1;
 	}
 
@@ -954,11 +1249,11 @@ TclSubstCompile(
     }
 
     while (count > 255) {
-	OP1(	CONCAT1, 255);
+	OP1(	STR_CONCAT1, 255);
 	count -= 254;
     }
     if (count > 1) {
-	OP1(	CONCAT1, count);
+	OP1(	STR_CONCAT1, count);
     }
 
     Tcl_FreeParse(&parse);
@@ -3152,6 +3447,51 @@ TclCompileYieldCmd(
 /*
  *----------------------------------------------------------------------
  *
+ * TclCompileYieldToCmd --
+ *
+ *	Procedure called to compile the "yieldto" command.
+ *
+ * Results:
+ *	Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
+ *	evaluation to runtime.
+ *
+ * Side effects:
+ *	Instructions are added to envPtr to execute the "yieldto" command at
+ *	runtime.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclCompileYieldToCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    DefineLineInformation;	/* TIP #280 */
+    Tcl_Token *tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    int i;
+
+    if (parsePtr->numWords < 2) {
+	return TCL_ERROR;
+    }
+
+    OP(		NS_CURRENT);
+    for (i = 1 ; i < parsePtr->numWords ; i++) {
+	CompileWord(envPtr, tokenPtr, interp, i);
+	tokenPtr = TokenAfter(tokenPtr);
+    }
+    OP4(	LIST, i);
+    OP(		YIELD_TO_INVOKE);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * CompileUnaryOpCmd --
  *
  *	Utility routine to compile the unary operator commands.
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index 5b716e6..f38ffa6 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -63,7 +63,7 @@ InstructionDesc const tclInstructionTable[] = {
 	/* Pop the topmost stack object */
     {"dup",		  1,   +1,         0,	{OPERAND_NONE}},
 	/* Duplicate the topmost stack object and push the result */
-    {"concat1",		  2,   INT_MIN,    1,	{OPERAND_UINT1}},
+    {"strcat",		  2,   INT_MIN,    1,	{OPERAND_UINT1}},
 	/* Concatenate the top op1 items and push result */
     {"invokeStk1",	  2,   INT_MIN,    1,	{OPERAND_UINT1}},
 	/* Invoke command named objv[0]; <objc,objv> = <op1,top op1> */
@@ -493,6 +493,7 @@ InstructionDesc const tclInstructionTable[] = {
 	 * qualified version, or produces the empty string if no such command
 	 * exists. Never generates errors.
 	 * Stack:  ... cmdName => ... fullCmdName */
+
     {"tclooSelf",	 1,	+1,	  0,	{OPERAND_NONE}},
 	/* Push the identity of the current TclOO object (i.e., the name of
 	 * its current public access command) on the stack. */
@@ -546,15 +547,96 @@ InstructionDesc const tclInstructionTable[] = {
 	 * until the matching stack depth is reached. */
 
     /* New foreach implementation */
-    {"foreach_start",	  5,   +2,          1,	{OPERAND_AUX4}},
+    {"foreach_start",	 5,	+2,	  1,	{OPERAND_AUX4}},
 	/* Initialize execution of a foreach loop. Operand is aux data index
 	 * of the ForeachInfo structure for the foreach command. It pushes 2
 	 * elements which hold runtime params for foreach_step, they are later
-	 * dropped by foreach_end together with the value lists. */ 
-    {"foreach_step",	  1,    0,         0,	{OPERAND_NONE}},
-	/* "Step" or begin next iteration of foreach loop. */
-    {"foreach_end",	  1,    0,         0,	{OPERAND_NONE}},
-    {"lmap_collect",	  1,   -1,         0,	{OPERAND_NONE}},
+	 * dropped by foreach_end together with the value lists. NOTE that the
+	 * iterator-tracker and info reference must not be passed to bytecodes
+	 * that handle normal Tcl values. NOTE that this instruction jumps to
+	 * the foreach_step instruction paired with it; the stack info below
+	 * is only nominal.
+	 * Stack: ... listObjs... => ... listObjs... iterTracker info */
+    {"foreach_step",	 1,	 0,	  0,	{OPERAND_NONE}},
+	/* "Step" or begin next iteration of foreach loop. Assigns to foreach
+	 * iteration variables. May jump to straight after the foreach_start
+	 * that pushed the iterTracker and info values. MUST be followed
+	 * immediately by a foreach_end.
+	 * Stack: ... listObjs... iterTracker info =>
+	 *				... listObjs... iterTracker info */
+    {"foreach_end",	 1,	 0,	  0,	{OPERAND_NONE}},
+	/* Clean up a foreach loop by dropping the info value, the tracker
+	 * value and the lists that were being iterated over.
+	 * Stack: ... listObjs... iterTracker info => ... */
+    {"lmap_collect",	 1,	-1,	  0,	{OPERAND_NONE}},
+	/* Appends the value at the top of the stack to the list located on
+	 * the stack the "other side" of the foreach-related values.
+	 * Stack: ... collector listObjs... iterTracker info value =>
+	 *			... collector listObjs... iterTracker info */
+
+    {"strtrim",		 1,	-1,	  0,	{OPERAND_NONE}},
+	/* [string trim] core: removes the characters (designated by the value
+	 * at the top of the stack) from both ends of the string and pushes
+	 * the resulting string.
+	 * Stack: ... string charset => ... trimmedString */
+    {"strtrimLeft",	 1,	-1,	  0,	{OPERAND_NONE}},
+	/* [string trimleft] core: removes the characters (designated by the
+	 * value at the top of the stack) from the left of the string and
+	 * pushes the resulting string.
+	 * Stack: ... string charset => ... trimmedString */
+    {"strtrimRight",	 1,	-1,	  0,	{OPERAND_NONE}},
+	/* [string trimright] core: removes the characters (designated by the
+	 * value at the top of the stack) from the right of the string and
+	 * pushes the resulting string.
+	 * Stack: ... string charset => ... trimmedString */
+
+    {"concatStk",	 5,	INT_MIN,  1,	{OPERAND_UINT4}},
+	/* Wrapper round Tcl_ConcatObj(), used for [concat] and [eval]. opnd
+	 * is number of values to concatenate.
+	 * Operation:	push concat(stk1 stk2 ... stktop) */
+
+    {"strcaseUpper",	 1,	0,	  0,	{OPERAND_NONE}},
+	/* [string toupper] core: converts whole string to upper case using
+	 * the default (extended "C" locale) rules.
+	 * Stack: ... string => ... newString */
+    {"strcaseLower",	 1,	0,	  0,	{OPERAND_NONE}},
+	/* [string tolower] core: converts whole string to upper case using
+	 * the default (extended "C" locale) rules.
+	 * Stack: ... string => ... newString */
+    {"strcaseTitle",	 1,	0,	  0,	{OPERAND_NONE}},
+	/* [string totitle] core: converts whole string to upper case using
+	 * the default (extended "C" locale) rules.
+	 * Stack: ... string => ... newString */
+    {"strreplace",	 1,	-3,	  0,	{OPERAND_NONE}},
+	/* [string replace] core: replaces a non-empty range of one string
+	 * with the contents of another.
+	 * Stack: ... string fromIdx toIdx replacement => ... newString */
+
+    {"originCmd",	 1,	0,	  0,	{OPERAND_NONE}},
+	/* Reports which command was the origin (via namespace import chain)
+	 * of the command named on the top of the stack.
+	 * Stack:  ... cmdName => ... fullOriginalCmdName */
+
+    {"tclooNext",	 2,	INT_MIN,  1,	{OPERAND_UINT1}},
+	/* Call the next item on the TclOO call chain, passing opnd arguments
+	 * (min 1, max 255, *includes* "next").  The result of the invoked
+	 * method implementation will be pushed on the stack in place of the
+	 * arguments (similar to invokeStk).
+	 * Stack:  ... "next" arg2 arg3 -- argN => ... result */
+    {"tclooNextClass",	 2,	INT_MIN,  1,	{OPERAND_UINT1}},
+	/* Call the following item on the TclOO call chain defined by class
+	 * className, passing opnd arguments (min 2, max 255, *includes*
+	 * "nextto" and the class name). The result of the invoked method
+	 * implementation will be pushed on the stack in place of the
+	 * arguments (similar to invokeStk).
+	 * Stack:  ... "nextto" className arg3 arg4 -- argN => ... result */
+
+    {"yieldToInvoke",	 1,	0,	  0,	{OPERAND_NONE}},
+	/* Makes the current coroutine yield the value at the top of the
+	 * stack, invoking the given command/args with resolution in the given
+	 * namespace (all packed into a list), and places the list of values
+	 * that are the response back on top of the stack when it resumes.
+	 * Stack:  ... [list ns cmd arg1 ... argN] => ... resumeList */
 
     {NULL, 0, 0, 0, {OPERAND_NONE}}
 };
@@ -2407,11 +2489,11 @@ TclCompileTokens(
      */
 
     while (numObjsToConcat > 255) {
-	TclEmitInstInt1(INST_CONCAT1, 255, envPtr);
+	TclEmitInstInt1(INST_STR_CONCAT1, 255, envPtr);
 	numObjsToConcat -= 254;	/* concat pushes 1 obj, the result */
     }
     if (numObjsToConcat > 1) {
-	TclEmitInstInt1(INST_CONCAT1, numObjsToConcat, envPtr);
+	TclEmitInstInt1(INST_STR_CONCAT1, numObjsToConcat, envPtr);
     }
 
     /*
@@ -2543,11 +2625,11 @@ TclCompileExprWords(
     }
     concatItems = 2*numWords - 1;
     while (concatItems > 255) {
-	TclEmitInstInt1(INST_CONCAT1, 255, envPtr);
+	TclEmitInstInt1(INST_STR_CONCAT1, 255, envPtr);
 	concatItems -= 254;
     }
     if (concatItems > 1) {
-	TclEmitInstInt1(INST_CONCAT1, concatItems, envPtr);
+	TclEmitInstInt1(INST_STR_CONCAT1, concatItems, envPtr);
     }
     TclEmitOpcode(INST_EXPR_STK, envPtr);
 }
diff --git a/generic/tclCompile.h b/generic/tclCompile.h
index 7c67f0a..95f583b 100644
--- a/generic/tclCompile.h
+++ b/generic/tclCompile.h
@@ -512,7 +512,7 @@ typedef struct ByteCode {
 #define INST_PUSH4			2
 #define INST_POP			3
 #define INST_DUP			4
-#define INST_CONCAT1			5
+#define INST_STR_CONCAT1		5
 #define INST_INVOKE_STK1		6
 #define INST_INVOKE_STK4		7
 #define INST_EVAL_STK			8
@@ -751,6 +751,8 @@ typedef struct ByteCode {
 #define INST_INFO_LEVEL_NUM		152
 #define INST_INFO_LEVEL_ARGS		153
 #define INST_RESOLVE_COMMAND		154
+
+/* For compilation relating to TclOO */
 #define INST_TCLOO_SELF			155
 #define INST_TCLOO_CLASS		156
 #define INST_TCLOO_NS			157
@@ -769,14 +771,32 @@ typedef struct ByteCode {
 #define INST_EXPAND_DROP		165
 
 /* New foreach implementation */
-
 #define INST_FOREACH_START              166
 #define INST_FOREACH_STEP               167
 #define INST_FOREACH_END                168
 #define INST_LMAP_COLLECT               169
 
+/* For compilation of [string trim] and related */
+#define INST_STR_TRIM			170
+#define INST_STR_TRIM_LEFT		171
+#define INST_STR_TRIM_RIGHT		172
+
+#define INST_CONCAT_STK			173
+
+#define INST_STR_UPPER			174
+#define INST_STR_LOWER			175
+#define INST_STR_TITLE			176
+#define INST_STR_REPLACE		177
+
+#define INST_ORIGIN_COMMAND		178
+
+#define INST_TCLOO_NEXT			179
+#define INST_TCLOO_NEXT_CLASS		180
+
+#define INST_YIELD_TO_INVOKE		181
+
 /* The last opcode */
-#define LAST_INST_OPCODE		169
+#define LAST_INST_OPCODE		181
 
 /*
  * Table describing the Tcl bytecode instructions: their name (for displaying
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 7a5ff77..a6e09dd 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -117,28 +117,24 @@ long		tclObjsShared[TCL_MAX_SHARED_OBJ_STATS] = { 0, 0, 0, 0, 0 };
 typedef struct {
     ByteCode *codePtr;		/* Constant until the BC returns */
 				/* -----------------------------------------*/
-    const unsigned char *pc;	/* These fields are used on return TO this */
-    ptrdiff_t *catchTop;	/* this level: they record the state when a */
-    int cleanup;		/* new codePtr was received for NR */
-    Tcl_Obj *auxObjList;	/* execution. */
-    CmdFrame cmdFrame;
+    ptrdiff_t *catchTop;	/* These fields are used on return TO this */
+    Tcl_Obj *auxObjList;	/* this level: they record the state when a */
+    CmdFrame cmdFrame;		/* new codePtr was received for NR */
+                                /* execution. */
     void *stack[1];		/* Start of the actual combined catch and obj
 				 * stacks; the struct will be expanded as
 				 * necessary */
 } TEBCdata;
 
 #define TEBC_YIELD() \
-    do {								\
-	esPtr->tosPtr = tosPtr;						\
-	TD->pc = pc;							\
-	TD->cleanup = cleanup;						\
-	TclNRAddCallback(interp, TEBCresume, TD, INT2PTR(1), NULL, NULL); \
+    do {						\
+	esPtr->tosPtr = tosPtr;				\
+	TclNRAddCallback(interp, TEBCresume,		\
+		TD, pc, INT2PTR(cleanup), NULL);	\
     } while (0)
 
 #define TEBC_DATA_DIG() \
     do {					\
-	pc = TD->pc;				\
-	cleanup = TD->cleanup;			\
 	tosPtr = esPtr->tosPtr;			\
     } while (0)
 
@@ -747,7 +743,8 @@ static Tcl_Obj **	StackAllocWords(Tcl_Interp *interp, int numWords);
 static Tcl_Obj **	StackReallocWords(Tcl_Interp *interp, int numWords);
 static Tcl_NRPostProc	CopyCallback;
 static Tcl_NRPostProc	ExprObjCallback;
-
+static Tcl_NRPostProc	FinalizeOONext;
+static Tcl_NRPostProc	FinalizeOONextFilter;
 static Tcl_NRPostProc   TEBCresume;
 
 /*
@@ -1943,6 +1940,41 @@ TclIncrObj(
 /*
  *----------------------------------------------------------------------
  *
+ * ArgumentBCEnter --
+ *
+ *	This is a helper for TclNRExecuteByteCode/TEBCresume that encapsulates
+ *	a code sequence that is fairly common in the code but *not* commonly
+ *	called.
+ *
+ * Results:
+ *	None
+ *
+ * Side effects:
+ *	May register information about the bytecode in the command frame.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+ArgumentBCEnter(
+    Tcl_Interp *interp,
+    ByteCode *codePtr,
+    TEBCdata *tdPtr,
+    const unsigned char *pc,
+    int objc,
+    Tcl_Obj **objv)
+{
+    int cmd;
+
+    if (GetSrcInfoForPc(pc, codePtr, NULL, NULL, &cmd)) {
+	TclArgumentBCEnter(interp, objv, objc, codePtr, &tdPtr->cmdFrame, cmd,
+		pc - codePtr->codeStart);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * TclNRExecuteByteCode --
  *
  *	This procedure executes the instructions of a ByteCode structure. It
@@ -1975,10 +2007,6 @@ TclNRExecuteByteCode(
 		* sizeof(void *);
     int numWords = (size + sizeof(Tcl_Obj *) - 1) / sizeof(Tcl_Obj *);
 
-    if (iPtr->execEnvPtr->rewind) {
-	return TCL_ERROR;
-    }
-
     codePtr->refCount++;
 
     /*
@@ -1997,9 +2025,7 @@ TclNRExecuteByteCode(
     esPtr->tosPtr = initTosPtr;
 
     TD->codePtr     = codePtr;
-    TD->pc	    = codePtr->codeStart;
     TD->catchTop    = initCatchTop;
-    TD->cleanup     = 0;
     TD->auxObjList  = NULL;
 
     /*
@@ -2029,8 +2055,8 @@ TclNRExecuteByteCode(
      * Push the callback for bytecode execution
      */
 
-    TclNRAddCallback(interp, TEBCresume, TD, /*resume*/ INT2PTR(0),
-	    NULL, NULL);
+    TclNRAddCallback(interp, TEBCresume, TD, /* pc */ NULL,
+	    /* cleanup */ INT2PTR(0), NULL);
     return TCL_OK;
 }
 
@@ -2093,7 +2119,8 @@ TEBCresume(
 
     Tcl_Obj **tosPtr;		/* Cached pointer to top of evaluation
 				 * stack. */
-    const unsigned char *pc;	/* The current program counter. */
+    const unsigned char *pc = data[1];
+                                /* The current program counter. */
     unsigned char inst;         /* The currently running instruction */
     
     /*
@@ -2101,7 +2128,7 @@ TEBCresume(
      * executing an instruction.
      */
 
-    int cleanup = 0;
+    int cleanup = PTR2INT(data[2]);
     Tcl_Obj *objResultPtr;
     int checkInterp;            /* Indicates when a check of interp readyness
 				 * is necessary. Set by CACHE_STACK_INFO() */
@@ -2129,16 +2156,17 @@ TEBCresume(
     TEBC_DATA_DIG();
 
 #ifdef TCL_COMPILE_DEBUG
-    if (!data[1] && (tclTraceExec >= 2)) {
+    if (!pc && (tclTraceExec >= 2)) {
 	PrintByteCodeInfo(codePtr);
 	fprintf(stdout, "  Starting stack top=%d\n", (int) CURR_DEPTH);
 	fflush(stdout);
     }
 #endif
 
-    if (!data[1]) {
+    if (!pc) {
 	/* bytecode is starting from scratch */
 	checkInterp = 0;
+	pc = codePtr->codeStart;
 	goto cleanup0;
     } else {
         /* resume from invocation */
@@ -2156,7 +2184,7 @@ TEBCresume(
 	}
 	iPtr->cmdFramePtr = bcFramePtr->nextPtr;
 	if (iPtr->flags & INTERP_DEBUG_FRAME) {
-	    TclArgumentBCRelease((Tcl_Interp *) iPtr, bcFramePtr);
+	    TclArgumentBCRelease(interp, bcFramePtr);
 	}
 	if (codePtr->flags & TCL_BYTECODE_RECOMPILE) {
 	    iPtr->flags |= ERR_ALREADY_LOGGED;
@@ -2409,9 +2437,12 @@ TEBCresume(
 	TRACE_APPEND(("\n"));
 	goto processExceptionReturn;
 
-    case INST_YIELD: {
-	CoroutineData *corPtr = iPtr->execEnvPtr->corPtr;
+    {
+	CoroutineData *corPtr;
+	int yieldParameter;
 
+    case INST_YIELD:
+	corPtr = iPtr->execEnvPtr->corPtr;
 	TRACE(("%.30s => ", O2S(OBJ_AT_TOS)));
 	if (!corPtr) {
 	    TRACE_APPEND(("ERROR: yield outside coroutine\n"));
@@ -2425,11 +2456,74 @@ TEBCresume(
 	}
 
 #ifdef TCL_COMPILE_DEBUG
-	TRACE_WITH_OBJ(("yield, result="), iPtr->objResultPtr);
-	if (traceInstructions) {
-	    fprintf(stdout, "\n");
+	if (tclTraceExec >= 2) {
+	    if (traceInstructions) {
+		TRACE_APPEND(("YIELD...\n"));
+	    } else {
+		fprintf(stdout, "%d: (%u) yielding value \"%.30s\"\n",
+			iPtr->numLevels, (unsigned)(pc - codePtr->codeStart),
+			Tcl_GetString(OBJ_AT_TOS));
+	    }
+	    fflush(stdout);
+	}
+#endif
+	yieldParameter = 0;
+	Tcl_SetObjResult(interp, OBJ_AT_TOS);
+	goto doYield;
+
+    case INST_YIELD_TO_INVOKE:
+	corPtr = iPtr->execEnvPtr->corPtr;
+	valuePtr = OBJ_AT_TOS;
+	if (!corPtr) {
+	    TRACE(("[%.30s] => ERROR: yield outside coroutine\n",
+		    O2S(valuePtr)));
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "yieldto can only be called in a coroutine", -1));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "COROUTINE", "ILLEGAL_YIELD",
+		    NULL);
+	    CACHE_STACK_INFO();
+	    goto gotError;
+	}
+	if (((Namespace *)TclGetCurrentNamespace(interp))->flags & NS_DYING) {
+	    TRACE(("[%.30s] => ERROR: yield in deleted\n",
+		    O2S(valuePtr)));
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "yieldto called in deleted namespace", -1));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "COROUTINE", "YIELDTO_IN_DELETED",
+		    NULL);
+	    CACHE_STACK_INFO();
+	    goto gotError;
+	}
+
+#ifdef TCL_COMPILE_DEBUG
+	if (tclTraceExec >= 2) {
+	    if (traceInstructions) {
+		TRACE(("[%.30s] => YIELD...\n", O2S(valuePtr)));
+	    } else {
+		/* FIXME: What is the right thing to trace? */
+		fprintf(stdout, "%d: (%u) yielding to [%.30s]\n",
+			iPtr->numLevels, (unsigned)(pc - codePtr->codeStart),
+			Tcl_GetString(valuePtr));
+	    }
+	    fflush(stdout);
 	}
 #endif
+
+	/*
+	 * Install a tailcall record in the caller and continue with the
+	 * yield. The yield is switched into multi-return mode (via the
+	 * 'yieldParameter').
+	 */
+
+	Tcl_IncrRefCount(valuePtr);
+	iPtr->execEnvPtr = corPtr->callerEEPtr;
+	TclSetTailcall(interp, valuePtr);
+	iPtr->execEnvPtr = corPtr->eePtr;
+	yieldParameter = (PTR2INT(NULL)+1);	/*==CORO_ACTIVATE_YIELDM*/
+
+    doYield:
 	/* TIP #280: Record the last piece of info needed by
 	 * 'TclGetSrcInfoForPc', and push the frame.
 	 */
@@ -2438,21 +2532,14 @@ TEBCresume(
 	iPtr->cmdFramePtr = bcFramePtr;
 
 	if (iPtr->flags & INTERP_DEBUG_FRAME) {
-	    int cmd;
-	    if (GetSrcInfoForPc(pc, codePtr, NULL, NULL, &cmd)) {
-		TclArgumentBCEnter((Tcl_Interp *) iPtr, objv, objc,
-			codePtr, bcFramePtr, cmd, pc - codePtr->codeStart);
-	    }
+	    ArgumentBCEnter(interp, codePtr, TD, pc, objc, objv);
 	}
 
 	pc++;
 	cleanup = 1;
 	TEBC_YIELD();
-	
-	Tcl_SetObjResult(interp, OBJ_AT_TOS);
 	TclNRAddCallback(interp, TclNRCoroutineActivateCallback, corPtr,
-		INT2PTR(0), NULL, NULL);
-
+		INT2PTR(yieldParameter), NULL, NULL);
 	return TCL_OK;
     }
 
@@ -2472,6 +2559,7 @@ TEBCresume(
 	}
 
 #ifdef TCL_COMPILE_DEBUG
+	/* FIXME: What is the right thing to trace? */
 	{
 	    register int i;
 
@@ -2564,7 +2652,7 @@ TEBCresume(
 	NEXT_INST_F(5, 0, 0);
     }
 
-    case INST_CONCAT1: {
+    case INST_STR_CONCAT1: {
 	int appendLen = 0;
 	char *bytes, *p;
 	Tcl_Obj **currPtr;
@@ -2713,6 +2801,17 @@ TEBCresume(
 	NEXT_INST_V(2, opnd, 1);
     }
 
+    case INST_CONCAT_STK:
+	/*
+	 * Pop the opnd (objc) top stack elements, run through Tcl_ConcatObj,
+	 * and then decrement their ref counts.
+	 */
+
+	opnd = TclGetUInt4AtPtr(pc+1);
+	objResultPtr = Tcl_ConcatObj(opnd, &OBJ_AT_DEPTH(opnd-1));
+	TRACE_WITH_OBJ(("%u => ", opnd), objResultPtr);
+	NEXT_INST_V(5, opnd, 1);
+
     case INST_EXPAND_START:
 	/*
 	 * Push an element to the auxObjList. This records the current
@@ -2901,11 +3000,7 @@ TEBCresume(
 	iPtr->cmdFramePtr = bcFramePtr;
 
 	if (iPtr->flags & INTERP_DEBUG_FRAME) {
-	    int cmd;
-	    if (GetSrcInfoForPc(pc, codePtr, NULL, NULL, &cmd)) {
-		TclArgumentBCEnter((Tcl_Interp *) iPtr, objv, objc,
-			codePtr, bcFramePtr, cmd, pc - codePtr->codeStart);
-	    }
+	    ArgumentBCEnter(interp, codePtr, TD, pc, objc, objv);
 	}
 
 	DECACHE_STACK_INFO();
@@ -2975,11 +3070,7 @@ TEBCresume(
 	bcFramePtr->data.tebc.pc = (char *) pc;
 	iPtr->cmdFramePtr = bcFramePtr;
 	if (iPtr->flags & INTERP_DEBUG_FRAME) {
-	    int cmd;
-	    if (GetSrcInfoForPc(pc, codePtr, NULL, NULL, &cmd)) {
-		TclArgumentBCEnter((Tcl_Interp *) iPtr, objv, objc,
-			codePtr, bcFramePtr, cmd, pc - codePtr->codeStart);
-	    }
+	    ArgumentBCEnter(interp, codePtr, TD, pc, objc, objv);
 	}
 	iPtr->ensembleRewrite.sourceObjs = objv;
 	iPtr->ensembleRewrite.numRemovedObjs = opnd;
@@ -4310,12 +4401,11 @@ TEBCresume(
 	register CallFrame *framePtr = iPtr->varFramePtr;
 	register CallFrame *rootFramePtr = iPtr->rootFramePtr;
 
+	TRACE(("\"%.30s\" => ", O2S(OBJ_AT_TOS)));
 	if (TclGetIntFromObj(interp, OBJ_AT_TOS, &level) != TCL_OK) {
-	    TRACE_WITH_OBJ(("\"%.30s\" => ERROR: ", O2S(OBJ_AT_TOS)),
-		    Tcl_GetObjResult(interp));
+	    TRACE_ERROR(interp);
 	    goto gotError;
 	}
-	TRACE(("%d => ", level));
 	if (level <= 0) {
 	    level += framePtr->level;
 	}
@@ -4337,20 +4427,54 @@ TEBCresume(
 	TRACE_APPEND(("%.30s\n", O2S(objResultPtr)));
 	NEXT_INST_F(1, 1, 1);
     }
-    case INST_RESOLVE_COMMAND: {
-	Tcl_Command cmd = Tcl_GetCommandFromObj(interp, OBJ_AT_TOS);
+    {
+	Tcl_Command cmd, origCmd;
 
+    case INST_RESOLVE_COMMAND:
+	cmd = Tcl_GetCommandFromObj(interp, OBJ_AT_TOS);
 	TclNewObj(objResultPtr);
 	if (cmd != NULL) {
 	    Tcl_GetCommandFullName(interp, cmd, objResultPtr);
 	}
 	TRACE_WITH_OBJ(("\"%.20s\" => ", O2S(OBJ_AT_TOS)), objResultPtr);
 	NEXT_INST_F(1, 1, 1);
+
+    case INST_ORIGIN_COMMAND:
+	TRACE(("\"%.30s\" => ", O2S(OBJ_AT_TOS)));
+	cmd = Tcl_GetCommandFromObj(interp, OBJ_AT_TOS);
+	if (cmd == NULL) {
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "invalid command name \"%s\"", TclGetString(OBJ_AT_TOS)));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "COMMAND",
+		    TclGetString(OBJ_AT_TOS), NULL);
+	    CACHE_STACK_INFO();
+	    TRACE_APPEND(("ERROR: not command\n"));
+	    goto gotError;
+	}
+	origCmd = TclGetOriginalCommand(cmd);
+	if (origCmd == NULL) {
+	    origCmd = cmd;
+	}
+	TclNewObj(objResultPtr);
+	Tcl_GetCommandFullName(interp, origCmd, objResultPtr);
+	TRACE_APPEND(("\"%.30s\"", O2S(OBJ_AT_TOS)));
+	NEXT_INST_F(1, 1, 1);
     }
-    case INST_TCLOO_SELF: {
-	CallFrame *framePtr = iPtr->varFramePtr;
+
+    /*
+     * -----------------------------------------------------------------
+     *	   Start of TclOO support instructions.
+     */
+
+    {
+	Object *oPtr;
+	CallFrame *framePtr;
 	CallContext *contextPtr;
+	int skip, newDepth;
 
+    case INST_TCLOO_SELF:
+	framePtr = iPtr->varFramePtr;
 	if (framePtr == NULL ||
 		!(framePtr->isProcCallFrame & FRAME_IS_METHOD)) {
 	    TRACE(("=> ERROR: no TclOO call context\n"));
@@ -4371,9 +4495,212 @@ TEBCresume(
 	objResultPtr = TclOOObjectName(interp, contextPtr->oPtr);
 	TRACE_WITH_OBJ(("=> "), objResultPtr);
 	NEXT_INST_F(1, 0, 1);
-    }
-    {
-	Object *oPtr;
+
+    case INST_TCLOO_NEXT_CLASS:
+	opnd = TclGetUInt1AtPtr(pc+1);
+	framePtr = iPtr->varFramePtr;
+	valuePtr = OBJ_AT_DEPTH(opnd - 2);
+	objv = &OBJ_AT_DEPTH(opnd - 1);
+	skip = 2;
+	TRACE(("%d => ", opnd));
+	if (framePtr == NULL ||
+		!(framePtr->isProcCallFrame & FRAME_IS_METHOD)) {
+	    TRACE_APPEND(("ERROR: no TclOO call context\n"));
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "nextto may only be called from inside a method",
+		    -1));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", NULL);
+	    CACHE_STACK_INFO();
+	    goto gotError;
+	}
+	contextPtr = framePtr->clientData;
+
+	oPtr = (Object *) Tcl_GetObjectFromObj(interp, valuePtr);
+	if (oPtr == NULL) {
+	    TRACE_APPEND(("ERROR: \"%.30s\" not object\n", O2S(valuePtr)));
+	    goto gotError;
+	} else {
+	    Class *classPtr = oPtr->classPtr;
+	    struct MInvoke *miPtr;
+	    int i;
+	    const char *methodType;
+
+	    if (classPtr == NULL) {
+		TRACE_APPEND(("ERROR: \"%.30s\" not class\n", O2S(valuePtr)));
+		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+			"\"%s\" is not a class", TclGetString(valuePtr)));
+		DECACHE_STACK_INFO();
+		Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_REQUIRED", NULL);
+		CACHE_STACK_INFO();
+		goto gotError;
+	    }
+
+	    for (i=contextPtr->index+1 ; i<contextPtr->callPtr->numChain ; i++) {
+		miPtr = contextPtr->callPtr->chain + i;
+		if (!miPtr->isFilter &&
+			miPtr->mPtr->declaringClassPtr == classPtr) {
+		    newDepth = i;
+#ifdef TCL_COMPILE_DEBUG
+		    if (tclTraceExec >= 2) {
+			if (traceInstructions) {
+			    strncpy(cmdNameBuf, TclGetString(objv[0]), 20);
+			} else {
+			    fprintf(stdout, "%d: (%u) invoking ",
+				    iPtr->numLevels,
+				    (unsigned)(pc - codePtr->codeStart));
+			}
+			for (i = 0;  i < opnd;  i++) {
+			    TclPrintObject(stdout, objv[i], 15);
+			    fprintf(stdout, " ");
+			}
+			fprintf(stdout, "\n");
+			fflush(stdout);
+		    }
+#endif /*TCL_COMPILE_DEBUG*/
+		    goto doInvokeNext;
+		}
+	    }
+
+	    if (contextPtr->callPtr->flags & CONSTRUCTOR) {
+		methodType = "constructor";
+	    } else if (contextPtr->callPtr->flags & DESTRUCTOR) {
+		methodType = "destructor";
+	    } else {
+		methodType = "method";
+	    }
+
+	    TRACE_APPEND(("ERROR: \"%.30s\" not on reachable chain\n",
+		    O2S(valuePtr)));
+	    for (i=contextPtr->index ; i>=0 ; i--) {
+		miPtr = contextPtr->callPtr->chain + i;
+		if (miPtr->isFilter
+			|| miPtr->mPtr->declaringClassPtr != classPtr) {
+		    continue;
+		}
+		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+			"%s implementation by \"%s\" not reachable from here",
+			methodType, TclGetString(valuePtr)));
+		DECACHE_STACK_INFO();
+		Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_REACHABLE",
+			NULL);
+		CACHE_STACK_INFO();
+		goto gotError;
+	    }
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "%s has no non-filter implementation by \"%s\"",
+		    methodType, TclGetString(valuePtr)));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_THERE", NULL);
+	    CACHE_STACK_INFO();
+	    goto gotError;
+	}
+
+    case INST_TCLOO_NEXT:
+	opnd = TclGetUInt1AtPtr(pc+1);
+	objv = &OBJ_AT_DEPTH(opnd - 1);
+	framePtr = iPtr->varFramePtr;
+	skip = 1;
+	TRACE(("%d => ", opnd));
+	if (framePtr == NULL ||
+		!(framePtr->isProcCallFrame & FRAME_IS_METHOD)) {
+	    TRACE_APPEND(("ERROR: no TclOO call context\n"));
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "next may only be called from inside a method",
+		    -1));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", NULL);
+	    CACHE_STACK_INFO();
+	    goto gotError;
+	}
+	contextPtr = framePtr->clientData;
+
+	newDepth = contextPtr->index + 1;
+	if (newDepth >= contextPtr->callPtr->numChain) {
+	    /*
+	     * We're at the end of the chain; generate an error message unless
+	     * the interpreter is being torn down, in which case we might be
+	     * getting here because of methods/destructors doing a [next] (or
+	     * equivalent) unexpectedly.
+	     */
+
+	    const char *methodType;
+
+	    if (contextPtr->callPtr->flags & CONSTRUCTOR) {
+		methodType = "constructor";
+	    } else if (contextPtr->callPtr->flags & DESTRUCTOR) {
+		methodType = "destructor";
+	    } else {
+		methodType = "method";
+	    }
+
+	    TRACE_APPEND(("ERROR: no TclOO next impl\n"));
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "no next %s implementation", methodType));
+	    DECACHE_STACK_INFO();
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "NOTHING_NEXT", NULL);
+	    CACHE_STACK_INFO();
+	    goto gotError;
+#ifdef TCL_COMPILE_DEBUG
+	} else if (tclTraceExec >= 2) {
+	    int i;
+
+	    if (traceInstructions) {
+		strncpy(cmdNameBuf, TclGetString(objv[0]), 20);
+	    } else {
+		fprintf(stdout, "%d: (%u) invoking ",
+			iPtr->numLevels, (unsigned)(pc - codePtr->codeStart));
+	    }
+	    for (i = 0;  i < opnd;  i++) {
+		TclPrintObject(stdout, objv[i], 15);
+		fprintf(stdout, " ");
+	    }
+	    fprintf(stdout, "\n");
+	    fflush(stdout);
+#endif /*TCL_COMPILE_DEBUG*/
+	}
+
+    doInvokeNext:
+	bcFramePtr->data.tebc.pc = (char *) pc;
+	iPtr->cmdFramePtr = bcFramePtr;
+
+	if (iPtr->flags & INTERP_DEBUG_FRAME) {
+	    ArgumentBCEnter(interp, codePtr, TD, pc, opnd, objv);
+	}
+
+	pcAdjustment = 2;
+	cleanup = opnd;
+	DECACHE_STACK_INFO();
+	iPtr->varFramePtr = framePtr->callerVarPtr;
+	pc += pcAdjustment;
+	TEBC_YIELD();
+
+	oPtr = contextPtr->oPtr;
+	if (oPtr->flags & FILTER_HANDLING) {
+	    TclNRAddCallback(interp, FinalizeOONextFilter,
+		    framePtr, contextPtr, INT2PTR(contextPtr->index),
+		    INT2PTR(contextPtr->skip));
+	} else {
+	    TclNRAddCallback(interp, FinalizeOONext,
+		    framePtr, contextPtr, INT2PTR(contextPtr->index),
+		    INT2PTR(contextPtr->skip));
+	}
+	contextPtr->skip = skip;
+	contextPtr->index = newDepth;
+	if (contextPtr->callPtr->chain[newDepth].isFilter
+		|| contextPtr->callPtr->flags & FILTER_HANDLING) {
+	    oPtr->flags |= FILTER_HANDLING;
+	} else {
+	    oPtr->flags &= ~FILTER_HANDLING;
+	}
+
+	{
+	    register Method *const mPtr =
+		    contextPtr->callPtr->chain[newDepth].mPtr;
+
+	    return mPtr->typePtr->callProc(mPtr->clientData, interp,
+		    (Tcl_ObjectContext) contextPtr, opnd, objv);
+	}
 
     case INST_TCLOO_IS_OBJECT:
 	oPtr = (Object *) Tcl_GetObjectFromObj(interp, OBJ_AT_TOS);
@@ -4407,6 +4734,7 @@ TEBCresume(
     }
 
     /*
+     *     End of TclOO support instructions.
      * -----------------------------------------------------------------
      *	   Start of INST_LIST and related instructions.
      */
@@ -4919,6 +5247,55 @@ TEBCresume(
 	TRACE(("\"%.20s\" => %d\n", O2S(valuePtr), length));
 	NEXT_INST_F(1, 1, 1);
 
+    case INST_STR_UPPER:
+	valuePtr = OBJ_AT_TOS;
+	TRACE(("\"%.20s\" => ", O2S(valuePtr)));
+	if (Tcl_IsShared(valuePtr)) {
+	    s1 = TclGetStringFromObj(valuePtr, &length);
+	    TclNewStringObj(objResultPtr, s1, length);
+	    length = Tcl_UtfToUpper(TclGetString(objResultPtr));
+	    Tcl_SetObjLength(objResultPtr, length);
+	    TRACE_APPEND(("\"%.20s\"\n", O2S(objResultPtr)));
+	    NEXT_INST_F(1, 1, 1);
+	} else {
+	    length = Tcl_UtfToUpper(TclGetString(valuePtr));
+	    Tcl_SetObjLength(valuePtr, length);
+	    TRACE_APPEND(("\"%.20s\"\n", O2S(valuePtr)));
+	    NEXT_INST_F(1, 0, 0);
+	}
+    case INST_STR_LOWER:
+	valuePtr = OBJ_AT_TOS;
+	TRACE(("\"%.20s\" => ", O2S(valuePtr)));
+	if (Tcl_IsShared(valuePtr)) {
+	    s1 = TclGetStringFromObj(valuePtr, &length);
+	    TclNewStringObj(objResultPtr, s1, length);
+	    length = Tcl_UtfToLower(TclGetString(objResultPtr));
+	    Tcl_SetObjLength(objResultPtr, length);
+	    TRACE_APPEND(("\"%.20s\"\n", O2S(objResultPtr)));
+	    NEXT_INST_F(1, 1, 1);
+	} else {
+	    length = Tcl_UtfToLower(TclGetString(valuePtr));
+	    Tcl_SetObjLength(valuePtr, length);
+	    TRACE_APPEND(("\"%.20s\"\n", O2S(valuePtr)));
+	    NEXT_INST_F(1, 0, 0);
+	}
+    case INST_STR_TITLE:
+	valuePtr = OBJ_AT_TOS;
+	TRACE(("\"%.20s\" => ", O2S(valuePtr)));
+	if (Tcl_IsShared(valuePtr)) {
+	    s1 = TclGetStringFromObj(valuePtr, &length);
+	    TclNewStringObj(objResultPtr, s1, length);
+	    length = Tcl_UtfToTitle(TclGetString(objResultPtr));
+	    Tcl_SetObjLength(objResultPtr, length);
+	    TRACE_APPEND(("\"%.20s\"\n", O2S(objResultPtr)));
+	    NEXT_INST_F(1, 1, 1);
+	} else {
+	    length = Tcl_UtfToTitle(TclGetString(valuePtr));
+	    Tcl_SetObjLength(valuePtr, length);
+	    TRACE_APPEND(("\"%.20s\"\n", O2S(valuePtr)));
+	    NEXT_INST_F(1, 0, 0);
+	}
+
     case INST_STR_INDEX:
 	value2Ptr = OBJ_AT_TOS;
 	valuePtr = OBJ_UNDER_TOS;
@@ -5027,6 +5404,179 @@ TEBCresume(
 	int length3;
 	Tcl_Obj *value3Ptr;
 
+    case INST_STR_REPLACE:
+	value3Ptr = POP_OBJECT();
+	valuePtr = OBJ_AT_DEPTH(2);
+	length = Tcl_GetCharLength(valuePtr) - 1;
+	TRACE(("\"%.20s\" %s %s \"%.20s\" => ", O2S(valuePtr),
+		O2S(OBJ_UNDER_TOS), O2S(OBJ_AT_TOS), O2S(value3Ptr)));
+	if (TclGetIntForIndexM(interp, OBJ_UNDER_TOS, length,
+		    &fromIdx) != TCL_OK
+	    || TclGetIntForIndexM(interp, OBJ_AT_TOS, length,
+		    &toIdx) != TCL_OK) {
+	    TclDecrRefCount(value3Ptr);
+	    TRACE_ERROR(interp);
+	    goto gotError;
+	}
+	TclDecrRefCount(OBJ_AT_TOS);
+	(void) POP_OBJECT();
+	TclDecrRefCount(OBJ_AT_TOS);
+	(void) POP_OBJECT();
+	if (fromIdx < 0) {
+	    fromIdx = 0;
+	}
+
+	if (fromIdx > toIdx || fromIdx > length) {
+	    TRACE_APPEND(("\"%.30s\"\n", O2S(valuePtr)));
+	    TclDecrRefCount(value3Ptr);
+	    NEXT_INST_F(1, 0, 0);
+	}
+
+	if (toIdx > length) {
+	    toIdx = length;
+	}
+
+	if (fromIdx == 0 && toIdx == length) {
+	    TclDecrRefCount(OBJ_AT_TOS);
+	    OBJ_AT_TOS = value3Ptr;
+	    TRACE_APPEND(("\"%.30s\"\n", O2S(value3Ptr)));
+	    NEXT_INST_F(1, 0, 0);
+	}
+
+	length3 = Tcl_GetCharLength(value3Ptr);
+
+	/*
+	 * Remove substring. In-place.
+	 */
+
+	if (length3 == 0 && !Tcl_IsShared(valuePtr) && toIdx == length) {
+	    TclDecrRefCount(value3Ptr);
+	    Tcl_SetObjLength(valuePtr, fromIdx);
+	    TRACE_APPEND(("\"%.30s\"\n", O2S(valuePtr)));
+	    NEXT_INST_F(1, 0, 0);
+	}
+
+	/*
+	 * See if we can splice in place. This happens when the number of
+	 * characters being replaced is the same as the number of characters
+	 * in the string to be inserted.
+	 */
+
+	if (length3 - 1 == toIdx - fromIdx) {
+	    unsigned char *bytes1, *bytes2;
+
+	    if (Tcl_IsShared(valuePtr)) {
+		objResultPtr = Tcl_DuplicateObj(valuePtr);
+		if (TclIsPureByteArray(objResultPtr)
+			&& TclIsPureByteArray(value3Ptr)) {
+		    bytes1 = Tcl_GetByteArrayFromObj(objResultPtr, NULL);
+		    bytes2 = Tcl_GetByteArrayFromObj(value3Ptr, NULL);
+		    memcpy(bytes1 + fromIdx, bytes2, length3);
+		} else {
+		    ustring1 = Tcl_GetUnicodeFromObj(objResultPtr, NULL);
+		    ustring2 = Tcl_GetUnicodeFromObj(value3Ptr, NULL);
+		    memcpy(ustring1 + fromIdx, ustring2,
+			    length3 * sizeof(Tcl_UniChar));
+
+		    /*
+		     * Magic! Flush the info in the string internal rep that
+		     * refers to the about-to-be-invalidated UTF-8 rep. This
+		     * sets the 'allocated' field of the String structure to 0
+		     * to indicate that a new buffer needs to be allocated.
+		     * This is safe; we know we've got a tclStringTypePtr set
+		     * at this point (post Tcl_GetUnicodeFromObj).
+		     */
+
+		    ((int *) objResultPtr->internalRep.otherValuePtr)[1] = 0;
+		}
+		Tcl_InvalidateStringRep(objResultPtr);
+		TRACE_APPEND(("\"%.30s\"\n", O2S(objResultPtr)));
+		NEXT_INST_F(1, 1, 1);
+	    } else {
+		if (TclIsPureByteArray(valuePtr)
+			&& TclIsPureByteArray(value3Ptr)) {
+		    bytes1 = Tcl_GetByteArrayFromObj(valuePtr, NULL);
+		    bytes2 = Tcl_GetByteArrayFromObj(value3Ptr, NULL);
+		    memcpy(bytes1 + fromIdx, bytes2, length3);
+		} else {
+		    ustring1 = Tcl_GetUnicodeFromObj(valuePtr, NULL);
+		    ustring2 = Tcl_GetUnicodeFromObj(value3Ptr, NULL);
+		    memcpy(ustring1 + fromIdx, ustring2,
+			    length3 * sizeof(Tcl_UniChar));
+
+		    /*
+		     * Magic! Flush the info in the string internal rep that
+		     * refers to the about-to-be-invalidated UTF-8 rep. This
+		     * sets the 'allocated' field of the String structure to 0
+		     * to indicate that a new buffer needs to be allocated.
+		     * This is safe; we know we've got a tclStringTypePtr set
+		     * at this point (post Tcl_GetUnicodeFromObj).
+		     */
+
+		    ((int *) objResultPtr->internalRep.otherValuePtr)[1] = 0;
+		}
+		Tcl_InvalidateStringRep(valuePtr);
+		TRACE_APPEND(("\"%.30s\"\n", O2S(valuePtr)));
+		NEXT_INST_F(1, 0, 0);
+	    }
+	}
+
+	/*
+	 * Get the unicode representation; this is where we guarantee to lose
+	 * bytearrays.
+	 */
+
+	ustring1 = Tcl_GetUnicodeFromObj(valuePtr, &length);
+	length--;
+
+	/*
+	 * Remove substring using copying.
+	 */
+
+	if (length3 == 0) {
+	    if (fromIdx > 0) {
+		objResultPtr = Tcl_NewUnicodeObj(ustring1, fromIdx);
+		if (toIdx < length) {
+		    Tcl_AppendUnicodeToObj(objResultPtr, ustring1 + toIdx + 1,
+			    length - toIdx);
+		}
+	    } else {
+		objResultPtr = Tcl_NewUnicodeObj(ustring1 + toIdx + 1,
+			length - toIdx);
+	    }
+	    TclDecrRefCount(value3Ptr);
+	    TRACE_APPEND(("\"%.30s\"\n", O2S(objResultPtr)));
+	    NEXT_INST_F(1, 1, 1);
+	}
+
+	/*
+	 * Splice string pieces by full copying.
+	 */
+
+	if (fromIdx > 0) {
+	    objResultPtr = Tcl_NewUnicodeObj(ustring1, fromIdx);
+	    Tcl_AppendObjToObj(objResultPtr, value3Ptr);
+	    if (toIdx < length) {
+		Tcl_AppendUnicodeToObj(objResultPtr, ustring1 + toIdx + 1,
+			length - toIdx);
+	    }
+	} else if (Tcl_IsShared(value3Ptr)) {
+	    objResultPtr = Tcl_DuplicateObj(value3Ptr);
+	    if (toIdx < length) {
+		Tcl_AppendUnicodeToObj(objResultPtr, ustring1 + toIdx + 1,
+			length - toIdx);
+	    }
+	} else {
+	    objResultPtr = value3Ptr;
+	    if (toIdx < length) {
+		Tcl_AppendUnicodeToObj(objResultPtr, ustring1 + toIdx + 1,
+			length - toIdx);
+	    }
+	}
+	TclDecrRefCount(value3Ptr);
+	TRACE_APPEND(("\"%.30s\"\n", O2S(objResultPtr)));
+	NEXT_INST_F(1, 1, 1);
+
     case INST_STR_MAP:
 	valuePtr = OBJ_AT_TOS;		/* "Main" string. */
 	value3Ptr = OBJ_UNDER_TOS;	/* "Target" string. */
@@ -5172,11 +5722,55 @@ TEBCresume(
 
 	JUMP_PEEPHOLE_F(match, 2, 2);
 
+    {
+	const char *string1, *string2;
+	int trim1, trim2;
+
+    case INST_STR_TRIM_LEFT:
+	valuePtr = OBJ_UNDER_TOS;	/* String */
+	value2Ptr = OBJ_AT_TOS;		/* TrimSet */
+	string2 = TclGetStringFromObj(value2Ptr, &length2);
+	string1 = TclGetStringFromObj(valuePtr, &length);
+	trim1 = TclTrimLeft(string1, length, string2, length2);
+	trim2 = 0;
+	goto createTrimmedString;
+    case INST_STR_TRIM_RIGHT:
+	valuePtr = OBJ_UNDER_TOS;	/* String */
+	value2Ptr = OBJ_AT_TOS;		/* TrimSet */
+	string2 = TclGetStringFromObj(value2Ptr, &length2);
+	string1 = TclGetStringFromObj(valuePtr, &length);
+	trim2 = TclTrimRight(string1, length, string2, length2);
+	trim1 = 0;
+	goto createTrimmedString;
+    case INST_STR_TRIM:
+	valuePtr = OBJ_UNDER_TOS;	/* String */
+	value2Ptr = OBJ_AT_TOS;		/* TrimSet */
+	string2 = TclGetStringFromObj(value2Ptr, &length2);
+	string1 = TclGetStringFromObj(valuePtr, &length);
+	trim1 = TclTrimLeft(string1, length, string2, length2);
+	if (trim1 < length) {
+	    trim2 = TclTrimRight(string1, length, string2, length2);
+	} else {
+	    trim2 = 0;
+	}
+    createTrimmedString:
+	if (trim1 == 0 && trim2 == 0) {
+	    TRACE_WITH_OBJ(("\"%.30s\" \"%.30s\" => ",
+		    O2S(valuePtr), O2S(value2Ptr)), valuePtr);
+	    NEXT_INST_F(1, 1, 0);
+	} else {
+	    objResultPtr = Tcl_NewStringObj(string1+trim1, length-trim1-trim2);
+	    TRACE_WITH_OBJ(("\"%.30s\" \"%.30s\" => ",
+		    O2S(valuePtr), O2S(value2Ptr)), objResultPtr);
+	    NEXT_INST_F(1, 2, 1);
+	}
+    }
+
     case INST_REGEXP:
 	cflags = TclGetInt1AtPtr(pc+1); /* RE compile flages like NOCASE */
 	valuePtr = OBJ_AT_TOS;		/* String */
 	value2Ptr = OBJ_UNDER_TOS;	/* Pattern */
-	TRACE(("%.20s %.20s => ", O2S(valuePtr), O2S(value2Ptr)));
+	TRACE(("\"%.30s\" \"%.30s\" => ", O2S(valuePtr), O2S(value2Ptr)));
 
 	/*
 	 * Compile and match the regular expression.
@@ -7264,6 +7858,58 @@ TEBCresume(
 #undef auxObjList
 #undef catchTop
 #undef TCONST
+
+static int
+FinalizeOONext(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    Interp *iPtr = (Interp *) interp;
+    CallContext *contextPtr = data[1];
+
+    /*
+     * Reset the variable lookup frame.
+     */
+
+    iPtr->varFramePtr = data[0];
+
+    /*
+     * Restore the call chain context index as we've finished the inner invoke
+     * and want to operate in the outer context again.
+     */
+
+    contextPtr->index = PTR2INT(data[2]);
+    contextPtr->skip = PTR2INT(data[3]);
+    contextPtr->oPtr->flags &= ~FILTER_HANDLING;
+    return result;
+}
+
+static int
+FinalizeOONextFilter(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    Interp *iPtr = (Interp *) interp;
+    CallContext *contextPtr = data[1];
+
+    /*
+     * Reset the variable lookup frame.
+     */
+
+    iPtr->varFramePtr = data[0];
+
+    /*
+     * Restore the call chain context index as we've finished the inner invoke
+     * and want to operate in the outer context again.
+     */
+
+    contextPtr->index = PTR2INT(data[2]);
+    contextPtr->skip = PTR2INT(data[3]);
+    contextPtr->oPtr->flags |= FILTER_HANDLING;
+    return result;
+}
 
 /*
  *----------------------------------------------------------------------
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 1362a03..c1fd5de 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -3391,6 +3391,9 @@ MODULE_SCOPE int	TclCompileBreakCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileCatchCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileConcatCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileContinueCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
@@ -3490,6 +3493,9 @@ MODULE_SCOPE int	TclCompileLassignCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileLindexCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileLinsertCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileListCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
@@ -3514,6 +3520,9 @@ MODULE_SCOPE int	TclCompileNamespaceCodeCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileNamespaceCurrentCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileNamespaceOriginCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileNamespaceQualifiersCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
@@ -3529,6 +3538,12 @@ MODULE_SCOPE int	TclCompileNamespaceWhichCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileNoOp(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileObjectNextCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileObjectNextToCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileObjectSelfCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
@@ -3571,6 +3586,27 @@ MODULE_SCOPE int	TclCompileStringMatchCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileStringRangeCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringReplaceCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringToLowerCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringToTitleCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringToUpperCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringTrimCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringTrimLCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringTrimRCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileSubstCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
@@ -3601,6 +3637,9 @@ MODULE_SCOPE int	TclCompileWhileCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileYieldCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileYieldToCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileBasic0ArgCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
diff --git a/generic/tclNamesp.c b/generic/tclNamesp.c
index c5c7dc8..b09a211 100644
--- a/generic/tclNamesp.c
+++ b/generic/tclNamesp.c
@@ -171,7 +171,7 @@ static const EnsembleImplMap defaultNamespaceMap[] = {
     {"forget",	   NamespaceForgetCmd,	TclCompileBasicMin0ArgCmd, NULL, NULL, 0},
     {"import",	   NamespaceImportCmd,	TclCompileBasicMin0ArgCmd, NULL, NULL, 0},
     {"inscope",	   NamespaceInscopeCmd,	NULL, NRNamespaceInscopeCmd, NULL, 0},
-    {"origin",	   NamespaceOriginCmd,	TclCompileBasic1ArgCmd, NULL, NULL, 0},
+    {"origin",	   NamespaceOriginCmd,	TclCompileNamespaceOriginCmd, NULL, NULL, 0},
     {"parent",	   NamespaceParentCmd,	TclCompileBasic0Or1ArgCmd, NULL, NULL, 0},
     {"path",	   NamespacePathCmd,	TclCompileBasic0Or1ArgCmd, NULL, NULL, 0},
     {"qualifiers", NamespaceQualifiersCmd, TclCompileNamespaceQualifiersCmd, NULL, NULL, 0},
diff --git a/generic/tclOO.c b/generic/tclOO.c
index 326f1ae..fff2a4b 100644
--- a/generic/tclOO.c
+++ b/generic/tclOO.c
@@ -437,10 +437,12 @@ InitFoundation(
      * ensemble.
      */
 
-    Tcl_CreateObjCommand(interp, "::oo::Helpers::next", TclOONextObjCmd, NULL,
-	    NULL);
-    Tcl_CreateObjCommand(interp, "::oo::Helpers::nextto", TclOONextToObjCmd,
-	    NULL, NULL);
+    cmdPtr = (Command *) Tcl_NRCreateCommand(interp, "::oo::Helpers::next",
+	    NULL, TclOONextObjCmd, NULL, NULL);
+    cmdPtr->compileProc = TclCompileObjectNextCmd;
+    cmdPtr = (Command *) Tcl_NRCreateCommand(interp, "::oo::Helpers::nextto",
+	    NULL, TclOONextToObjCmd, NULL, NULL);
+    cmdPtr->compileProc = TclCompileObjectNextToCmd;
     cmdPtr = (Command *) Tcl_CreateObjCommand(interp, "::oo::Helpers::self",
 	    TclOOSelfObjCmd, NULL, NULL);
     cmdPtr->compileProc = TclCompileObjectSelfCmd;
diff --git a/generic/tclOOBasic.c b/generic/tclOOBasic.c
index 39b7878..3000bdd 100644
--- a/generic/tclOOBasic.c
+++ b/generic/tclOOBasic.c
@@ -17,16 +17,11 @@
 #include "tclOOInt.h"
 
 static inline Tcl_Object *AddConstructionFinalizer(Tcl_Interp *interp);
-static int		AfterNRDestructor(ClientData data[],
-			    Tcl_Interp *interp, int result);
-static int		DecrRefsPostClassConstructor(ClientData data[],
-			    Tcl_Interp *interp, int result);
-static int		FinalizeConstruction(ClientData data[],
-			    Tcl_Interp *interp, int result);
-static int		FinalizeEval(ClientData data[],
-			    Tcl_Interp *interp, int result);
-static int		RestoreFrame(ClientData data[],
-			    Tcl_Interp *interp, int result);
+static Tcl_NRPostProc	AfterNRDestructor;
+static Tcl_NRPostProc	DecrRefsPostClassConstructor;
+static Tcl_NRPostProc	FinalizeConstruction;
+static Tcl_NRPostProc	FinalizeEval;
+static Tcl_NRPostProc	NextRestoreFrame;
 
 /*
  * ----------------------------------------------------------------------
@@ -808,7 +803,7 @@ TclOONextObjCmd(
      * that this is like [uplevel 1] and not [eval].
      */
 
-    TclNRAddCallback(interp, RestoreFrame, framePtr, NULL, NULL, NULL);
+    TclNRAddCallback(interp, NextRestoreFrame, framePtr, NULL,NULL,NULL);
     iPtr->varFramePtr = framePtr->callerVarPtr;
     return TclNRObjectContextInvokeNext(interp, context, objc, objv, 1);
 }
@@ -826,6 +821,7 @@ TclOONextToObjCmd(
     CallContext *contextPtr;
     int i;
     Tcl_Object object;
+    const char *methodType;
 
     /*
      * Start with sanity checks on the calling context to make sure that we
@@ -877,8 +873,8 @@ TclOONextToObjCmd(
 	     * context. Note that this is like [uplevel 1] and not [eval].
 	     */
 
-	    TclNRAddCallback(interp, RestoreFrame, framePtr, contextPtr,
-		    INT2PTR(contextPtr->index), NULL);
+	    TclNRAddCallback(interp, NextRestoreFrame, framePtr,
+		    contextPtr, INT2PTR(contextPtr->index), NULL);
 	    contextPtr->index = i-1;
 	    iPtr->varFramePtr = framePtr->callerVarPtr;
 	    return TclNRObjectContextInvokeNext(interp,
@@ -891,24 +887,35 @@ TclOONextToObjCmd(
      * is on the chain but unreachable, or not on the chain at all.
      */
 
+    if (contextPtr->callPtr->flags & CONSTRUCTOR) {
+	methodType = "constructor";
+    } else if (contextPtr->callPtr->flags & DESTRUCTOR) {
+	methodType = "destructor";
+    } else {
+	methodType = "method";
+    }
+
     for (i=contextPtr->index ; i>=0 ; i--) {
 	struct MInvoke *miPtr = contextPtr->callPtr->chain + i;
 
 	if (!miPtr->isFilter && miPtr->mPtr->declaringClassPtr == classPtr) {
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-		    "method implementation by \"%s\" not reachable from here",
-		    TclGetString(objv[1])));
+		    "%s implementation by \"%s\" not reachable from here",
+		    methodType, TclGetString(objv[1])));
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_REACHABLE",
+		    NULL);
 	    return TCL_ERROR;
 	}
     }
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-	    "method has no non-filter implementation by \"%s\"",
-	    TclGetString(objv[1])));
+	    "%s has no non-filter implementation by \"%s\"",
+	    methodType, TclGetString(objv[1])));
+    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_THERE", NULL);
     return TCL_ERROR;
 }
 
 static int
-RestoreFrame(
+NextRestoreFrame(
     ClientData data[],
     Tcl_Interp *interp,
     int result)
diff --git a/generic/tclOptimize.c b/generic/tclOptimize.c
index 74de7a3..827d89d 100644
--- a/generic/tclOptimize.c
+++ b/generic/tclOptimize.c
@@ -191,7 +191,7 @@ TrimUnreachable(
  * ConvertZeroEffectToNOP --
  *
  *	Replace PUSH/POP sequences (when non-hazardous) with NOPs. Also
- *	replace PUSH empty/CONCAT and TRY_CVT_NUMERIC (when followed by an
+ *	replace PUSH empty/STR_CONCAT and TRY_CVT_NUMERIC (when followed by an
  *	operation that guarantees the check for arithmeticity) and eliminate
  *	LNOT when we can invert the following JUMP condition.
  *
@@ -227,7 +227,7 @@ ConvertZeroEffectToNOP(
 	case INST_PUSH1:
 	    if (nextInst == INST_POP) {
 		blank = size + InstLength(nextInst);
-	    } else if (nextInst == INST_CONCAT1
+	    } else if (nextInst == INST_STR_CONCAT1
 		    && TclGetUInt1AtPtr(currentInstPtr + size + 1) == 2) {
 		Tcl_Obj *litPtr = TclFetchLiteral(envPtr,
 			TclGetUInt1AtPtr(currentInstPtr + 1));
@@ -242,7 +242,7 @@ ConvertZeroEffectToNOP(
 	case INST_PUSH4:
 	    if (nextInst == INST_POP) {
 		blank = size + 1;
-	    } else if (nextInst == INST_CONCAT1
+	    } else if (nextInst == INST_STR_CONCAT1
 		    && TclGetUInt1AtPtr(currentInstPtr + size + 1) == 2) {
 		Tcl_Obj *litPtr = TclFetchLiteral(envPtr,
 			TclGetUInt4AtPtr(currentInstPtr + 1));
diff --git a/generic/tclProc.c b/generic/tclProc.c
index db726c4..02f1fc5 100644
--- a/generic/tclProc.c
+++ b/generic/tclProc.c
@@ -1855,9 +1855,39 @@ InterpProcNR2(
     }
 
     /*
-     * Process the result code.
+     * Free the stack-allocated compiled locals and CallFrame. It is important
+     * to pop the call frame without freeing it first: the compiledLocals
+     * cannot be freed before the frame is popped, as the local variables must
+     * be deleted. But the compiledLocals must be freed first, as they were
+     * allocated later on the stack.
      */
 
+    if (result != TCL_OK) {
+	goto process;
+    }
+    
+    done: 
+    if (TCL_DTRACE_PROC_RESULT_ENABLED()) {
+	int l = iPtr->varFramePtr->isProcCallFrame & FRAME_IS_LAMBDA ? 1 : 0;
+	Tcl_Obj *r = Tcl_GetObjResult(interp);
+
+	TCL_DTRACE_PROC_RESULT(l < iPtr->varFramePtr->objc ?
+		TclGetString(iPtr->varFramePtr->objv[l]) : NULL, result,
+		TclGetString(r), r);
+    }
+
+    freePtr = iPtr->framePtr;
+    Tcl_PopCallFrame(interp);		/* Pop but do not free. */
+    TclStackFree(interp, freePtr->compiledLocals);
+					/* Free compiledLocals. */
+    TclStackFree(interp, freePtr);	/* Free CallFrame. */
+    return result;
+
+    /*
+     * Process any non-TCL_OK result code.
+     */
+
+    process:
     switch (result) {
     case TCL_RETURN:
 	/*
@@ -1892,46 +1922,8 @@ InterpProcNR2(
 	 */
 
 	errorProc(interp, procNameObj);
-
-    default:
-	/*
-	 * Process other results (OK and non-standard) by doing nothing
-	 * special, skipping directly to the code afterwards that cleans up
-	 * associated memory.
-	 *
-	 * Non-standard results are processed by passing them through quickly.
-	 * This means they all work as exceptions, unwinding the stack quickly
-	 * and neatly. Who knows how well they are handled by third-party code
-	 * though...
-	 */
-
-	(void) 0;		/* do nothing */
-    }
-
-    if (TCL_DTRACE_PROC_RESULT_ENABLED()) {
-	int l = iPtr->varFramePtr->isProcCallFrame & FRAME_IS_LAMBDA ? 1 : 0;
-	Tcl_Obj *r = Tcl_GetObjResult(interp);
-
-	TCL_DTRACE_PROC_RESULT(l < iPtr->varFramePtr->objc ?
-		TclGetString(iPtr->varFramePtr->objv[l]) : NULL, result,
-		TclGetString(r), r);
     }
-
-    /*
-     * Free the stack-allocated compiled locals and CallFrame. It is important
-     * to pop the call frame without freeing it first: the compiledLocals
-     * cannot be freed before the frame is popped, as the local variables must
-     * be deleted. But the compiledLocals must be freed first, as they were
-     * allocated later on the stack.
-     */
-
-    freePtr = iPtr->framePtr;
-    Tcl_PopCallFrame(interp);		/* Pop but do not free. */
-    TclStackFree(interp, freePtr->compiledLocals);
-					/* Free compiledLocals. */
-    TclStackFree(interp, freePtr);	/* Free CallFrame. */
-
-    return result;
+    goto done;
 }
 
 /*
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index 16d0a17..e9a2b86 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -1281,23 +1281,43 @@ Tcl_AppendObjToObj(
 
     if ((TclIsPureByteArray(objPtr) || objPtr->bytes == tclEmptyStringRep)
 	    && TclIsPureByteArray(appendObjPtr)) {
-	unsigned char *bytesSrc;
-	int lengthSrc, lengthTotal;
 
 	/*
-	 * We do not assume that objPtr and appendObjPtr must be distinct!
-	 * This makes this code a bit more complex than it otherwise would be,
-	 * but in turn makes it much safer.
+	 * You might expect the code here to be
+	 *
+	 *  bytes = Tcl_GetByteArrayFromObj(appendObjPtr, &length);
+	 *  TclAppendBytesToByteArray(objPtr, bytes, length);
+	 *
+	 * and essentially all of the time that would be fine.  However,
+	 * it would run into trouble in the case where objPtr and
+	 * appendObjPtr point to the same thing.  That may never be a
+	 * good idea.  It seems to violate Copy On Write, and we don't
+	 * have any tests for the situation, since making any Tcl commands
+	 * that call Tcl_AppendObjToObj() do that appears impossible
+	 * (They honor Copy On Write!).  For the sake of extensions that
+	 * go off into that realm, though, here's a more complex approach
+	 * that can handle all the cases.
 	 */
 
+	/* Get lengths */
+	int lengthSrc;
+
 	(void) Tcl_GetByteArrayFromObj(objPtr, &length);
 	(void) Tcl_GetByteArrayFromObj(appendObjPtr, &lengthSrc);
-	lengthTotal = length + lengthSrc;
-	if (((length > lengthSrc) ? length : lengthSrc) > lengthTotal) {
-	    Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
-	}
-	bytesSrc = Tcl_GetByteArrayFromObj(appendObjPtr, NULL);
-	TclAppendBytesToByteArray(objPtr, bytesSrc, lengthSrc);
+
+	/* Grow buffer enough for the append */
+	TclAppendBytesToByteArray(objPtr, NULL, lengthSrc);
+
+	/* Reset objPtr back to the original value */
+	Tcl_SetByteArrayLength(objPtr, length);
+
+	/*
+	 * Now do the append knowing that buffer growth cannot cause
+	 * any trouble.
+	 */
+
+	TclAppendBytesToByteArray(objPtr,
+		Tcl_GetByteArrayFromObj(appendObjPtr, NULL), lengthSrc);
 	return;
     }
 
diff --git a/generic/tclStringTrim.h b/generic/tclStringTrim.h
new file mode 100644
index 0000000..030e4ec
--- /dev/null
+++ b/generic/tclStringTrim.h
@@ -0,0 +1,43 @@
+/*
+ * tclStringTrim.h --
+ *
+ *	This file contains the definition of what characters are to be trimmed
+ *	from a string by [string trim] by default. It's only needed by Tcl's
+ *	implementation; it does not form a public or private API at all.
+ *
+ * Copyright (c) 1987-1993 The Regents of the University of California.
+ * Copyright (c) 1994-1997 Sun Microsystems, Inc.
+ * Copyright (c) 1998-2000 Scriptics Corporation.
+ * Copyright (c) 2002 ActiveState Corporation.
+ * Copyright (c) 2003-2013 Donal K. Fellows.
+ *
+ * See the file "license.terms" for information on usage and redistribution of
+ * this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ */
+
+#ifndef TCL_STRING_TRIM_H
+#define TCL_STRING_TRIM_H
+
+/*
+ * Default set of characters to trim in [string trim] and friends. This is a
+ * UTF-8 literal string containing all Unicode space characters. [TIP #413]
+ */
+
+MODULE_SCOPE const char tclDefaultTrimSet[];
+
+/*
+ * The whitespace trimming set used when [concat]enating. This is a subset of
+ * the above, and deliberately so.
+ */
+
+#define CONCAT_TRIM_SET " \f\v\r\t\n"
+
+#endif /* TCL_STRING_TRIM_H */
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index 7060b1d..9ec9c99 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -14,6 +14,7 @@
 
 #include "tclInt.h"
 #include "tclParse.h"
+#include "tclStringTrim.h"
 #include <math.h>
 
 /*
@@ -1719,8 +1720,7 @@ TclTrimLeft(
  */
 
 /* The whitespace characters trimmed during [concat] operations */
-#define CONCAT_WS " \f\v\r\t\n"
-#define CONCAT_WS_SIZE (int) (sizeof(CONCAT_WS "") - 1)
+#define CONCAT_WS_SIZE (int) (sizeof(CONCAT_TRIM_SET "") - 1)
 
 char *
 Tcl_Concat(
@@ -1776,7 +1776,8 @@ Tcl_Concat(
 	 * Trim away the leading whitespace.
 	 */
 
-	trim = TclTrimLeft(element, elemLength, CONCAT_WS, CONCAT_WS_SIZE);
+	trim = TclTrimLeft(element, elemLength, CONCAT_TRIM_SET,
+		CONCAT_WS_SIZE);
 	element += trim;
 	elemLength -= trim;
 
@@ -1785,7 +1786,8 @@ Tcl_Concat(
 	 * a final backslash character.
 	 */
 
-	trim = TclTrimRight(element, elemLength, CONCAT_WS, CONCAT_WS_SIZE);
+	trim = TclTrimRight(element, elemLength, CONCAT_TRIM_SET,
+		CONCAT_WS_SIZE);
 	trim -= trim && (element[elemLength - trim - 1] == '\\');
 	elemLength -= trim;
 
@@ -1910,7 +1912,8 @@ Tcl_ConcatObj(
 	 * Trim away the leading whitespace.
 	 */
 
-	trim = TclTrimLeft(element, elemLength, CONCAT_WS, CONCAT_WS_SIZE);
+	trim = TclTrimLeft(element, elemLength, CONCAT_TRIM_SET,
+		CONCAT_WS_SIZE);
 	element += trim;
 	elemLength -= trim;
 
@@ -1919,7 +1922,8 @@ Tcl_ConcatObj(
 	 * a final backslash character.
 	 */
 
-	trim = TclTrimRight(element, elemLength, CONCAT_WS, CONCAT_WS_SIZE);
+	trim = TclTrimRight(element, elemLength, CONCAT_TRIM_SET,
+		CONCAT_WS_SIZE);
 	trim -= trim && (element[elemLength - trim - 1] == '\\');
 	elemLength -= trim;
 
diff --git a/tests/coroutine.test b/tests/coroutine.test
index a360fd5..05b58c9 100644
--- a/tests/coroutine.test
+++ b/tests/coroutine.test
@@ -1,4 +1,4 @@
-# Commands covered:  coroutine, yield, [info coroutine]
+# Commands covered:  coroutine, yield, yieldto, [info coroutine]
 #
 # This file contains a collection of tests for experimental commands that are
 # found in ::tcl::unsupported. The tests will migrate to normal test files
@@ -612,7 +612,6 @@ test coroutine-7.3 {yielding between coroutines} -body {
 } -cleanup {
     catch {rename juggler ""}
 } -result {{{a b c d e} ::j1 {a b c d} ::j2 {a b c} ::j3 {a b} ::j1 a ::j2} {} {} {}}
-
 test coroutine-7.4 {Bug 8ff0cb9fe1} -setup {
     proc foo {a b} {catch yield; return 1}
 } -cleanup {
@@ -620,7 +619,6 @@ test coroutine-7.4 {Bug 8ff0cb9fe1} -setup {
 } -body {
     coroutine demo lsort -command foo {a b}
 } -result {b a}
-
 test coroutine-7.5 {return codes} {
     set result {}
     foreach code {0 1 2 3 4 5} {
@@ -628,14 +626,12 @@ test coroutine-7.5 {return codes} {
     }
     set result
 } {0 1 2 3 4 5}
-
 test coroutine-7.6 {Early yield crashes} {
     proc foo args {}
     trace add execution foo enter {catch yield}
     coroutine demo foo
     rename foo {}
 } {}
-
 test coroutine-7.7 {Bug 2486550} -setup {
     interp hide {} yield
 } -body {
@@ -644,6 +640,92 @@ test coroutine-7.7 {Bug 2486550} -setup {
     demo
     interp expose {} yield
 } -result ok
+test coroutine-7.8 {yieldto context nuke: Bug a90d9331bc} -setup {
+    namespace eval cotest {}
+    set ::result ""
+} -body {
+    proc cotest::body {} {
+	lappend ::result a
+	yield OUT
+	lappend ::result b
+	yieldto ::return -level 0 123
+	lappend ::result c
+	return
+    }
+    lappend ::result [coroutine cotest cotest::body]
+    namespace delete cotest
+    namespace eval cotest {}
+    lappend ::result [cotest]
+    cotest
+    return $result
+} -returnCodes error -cleanup {
+    catch {namespace delete ::cotest}
+    catch {rename cotest ""}
+} -result {yieldto called in deleted namespace}
+test coroutine-7.9 {yieldto context nuke: Bug a90d9331bc} -setup {
+    namespace eval cotest {}
+    set ::result ""
+} -body {
+    proc cotest::body {} {
+	set y ::yieldto
+	lappend ::result a
+	yield OUT
+	lappend ::result b
+	$y ::return -level 0 123
+	lappend ::result c
+	return
+    }
+    lappend ::result [coroutine cotest cotest::body]
+    namespace delete cotest
+    namespace eval cotest {}
+    lappend ::result [cotest]
+    cotest
+    return $result
+} -returnCodes error -cleanup {
+    catch {namespace delete ::cotest}
+    catch {rename cotest ""}
+} -result {yieldto called in deleted namespace}
+test coroutine-7.10 {yieldto context nuke: Bug a90d9331bc} -setup {
+    namespace eval cotest {}
+    set ::result ""
+} -body {
+    proc cotest::body {} {
+	lappend ::result a
+	yield OUT
+	lappend ::result b
+	yieldto ::return -level 0 -cotest [namespace delete ::cotest] 123
+	lappend ::result c
+	return
+    }
+    lappend ::result [coroutine cotest cotest::body]
+    lappend ::result [cotest]
+    cotest
+    return $result
+} -returnCodes error -cleanup {
+    catch {namespace delete ::cotest}
+    catch {rename cotest ""}
+} -result {yieldto called in deleted namespace}
+test coroutine-7.11 {yieldto context nuke: Bug a90d9331bc} -setup {
+    namespace eval cotest {}
+    set ::result ""
+} -body {
+    proc cotest::body {} {
+	set y ::yieldto
+	lappend ::result a
+	yield OUT
+	lappend ::result b
+	$y ::return -level 0 -cotest [namespace delete ::cotest] 123
+	lappend ::result c
+	return
+    }
+    lappend ::result [coroutine cotest cotest::body]
+    lappend ::result [cotest]
+    cotest
+    return $result
+} -returnCodes error -cleanup {
+    catch {namespace delete ::cotest}
+    catch {rename cotest ""}
+} -result {yieldto called in deleted namespace}
 
 
 # cleanup
diff --git a/unix/Makefile.in b/unix/Makefile.in
index 12cfbcf..a2dc1c6 100644
--- a/unix/Makefile.in
+++ b/unix/Makefile.in
@@ -1033,6 +1033,7 @@ IOHDR=$(GENERIC_DIR)/tclIO.h
 MATHHDRS=$(GENERIC_DIR)/tommath.h $(GENERIC_DIR)/tclTomMath.h
 PARSEHDR=$(GENERIC_DIR)/tclParse.h
 NREHDR=$(GENERIC_DIR)/tclInt.h
+TRIMHDR=$(GENERIC_DIR)/tclStringTrim.h
 
 regcomp.o: $(REGHDRS) $(GENERIC_DIR)/regcomp.c $(GENERIC_DIR)/regc_lex.c \
 		$(GENERIC_DIR)/regc_color.c $(GENERIC_DIR)/regc_locale.c \
@@ -1078,7 +1079,7 @@ tclCmdAH.o: $(GENERIC_DIR)/tclCmdAH.c
 tclCmdIL.o: $(GENERIC_DIR)/tclCmdIL.c $(TCLREHDRS)
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclCmdIL.c
 
-tclCmdMZ.o: $(GENERIC_DIR)/tclCmdMZ.c $(TCLREHDRS)
+tclCmdMZ.o: $(GENERIC_DIR)/tclCmdMZ.c $(TCLREHDRS) $(TRIMHDR)
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclCmdMZ.c
 
 tclDate.o: $(GENERIC_DIR)/tclDate.c
@@ -1090,7 +1091,7 @@ tclCompCmds.o: $(GENERIC_DIR)/tclCompCmds.c $(COMPILEHDR)
 tclCompCmdsGR.o: $(GENERIC_DIR)/tclCompCmdsGR.c $(COMPILEHDR)
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclCompCmdsGR.c
 
-tclCompCmdsSZ.o: $(GENERIC_DIR)/tclCompCmdsSZ.c $(COMPILEHDR)
+tclCompCmdsSZ.o: $(GENERIC_DIR)/tclCompCmdsSZ.c $(COMPILEHDR) $(TRIMHDR)
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclCompCmdsSZ.c
 
 tclCompExpr.o: $(GENERIC_DIR)/tclCompExpr.c $(COMPILEHDR)
@@ -1307,7 +1308,7 @@ tclStubInit.o: $(GENERIC_DIR)/tclStubInit.c
 tclTrace.o: $(GENERIC_DIR)/tclTrace.c
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclTrace.c
 
-tclUtil.o: $(GENERIC_DIR)/tclUtil.c $(PARSEHDR)
+tclUtil.o: $(GENERIC_DIR)/tclUtil.c $(PARSEHDR) $(TRIMHDR)
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclUtil.c
 
 tclUtf.o: $(GENERIC_DIR)/tclUtf.c $(GENERIC_DIR)/tclUniData.c