Index: generic/tclBasic.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclBasic.c,v
retrieving revision 1.457
diff -u -p -r1.457 tclBasic.c
--- generic/tclBasic.c	5 Jun 2010 16:24:26 -0000	1.457
+++ generic/tclBasic.c	7 Jun 2010 23:37:14 -0000
@@ -542,6 +542,8 @@ Tcl_CreateInterp(void)
     Tcl_IncrRefCount(iPtr->upLiteral);
     TclNewLiteralStringObj(iPtr->callLiteral,"CALL");
     Tcl_IncrRefCount(iPtr->callLiteral);
+    TclNewLiteralStringObj(iPtr->innerLiteral,"INNER");
+    Tcl_IncrRefCount(iPtr->innerLiteral);
     iPtr->errorCode = NULL;
     TclNewLiteralStringObj(iPtr->ecVar, "::errorCode");
     Tcl_IncrRefCount(iPtr->ecVar);
@@ -1486,6 +1488,7 @@ DeleteInterpProc(
     iPtr->errorStack = NULL;
     Tcl_DecrRefCount(iPtr->upLiteral);
     Tcl_DecrRefCount(iPtr->callLiteral);
+    Tcl_DecrRefCount(iPtr->innerLiteral);
     if (iPtr->returnOpts) {
 	Tcl_DecrRefCount(iPtr->returnOpts);
     }
Index: generic/tclCompCmds.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclCompCmds.c,v
retrieving revision 1.169
diff -u -p -r1.169 tclCompCmds.c
--- generic/tclCompCmds.c	30 Apr 2010 09:23:06 -0000	1.169
+++ generic/tclCompCmds.c	7 Jun 2010 23:37:18 -0000
@@ -3613,6 +3613,7 @@ TclCompileSyntaxError(
     int numBytes;
     const char *bytes = TclGetStringFromObj(msg, &numBytes);
 
+    TclErrorStackResetIf(interp, bytes, numBytes);
     TclEmitPush(TclRegisterNewLiteral(envPtr, bytes, numBytes), envPtr);
     CompileReturnInternal(envPtr, INST_SYNTAX, TCL_ERROR, 0,
 	    Tcl_GetReturnOptions(interp, TCL_ERROR));
Index: generic/tclCompile.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclCompile.c,v
retrieving revision 1.186
diff -u -p -r1.186 tclCompile.c
--- generic/tclCompile.c	14 May 2010 08:22:02 -0000	1.186
+++ generic/tclCompile.c	7 Jun 2010 23:37:22 -0000
@@ -4244,6 +4244,95 @@ FormatInstruction(
 /*
  *----------------------------------------------------------------------
  *
+ * TclGetInnerContext --
+ *
+ *	If possible, returns a list capturing the inner context. Otherwise
+ *	return NULL.
+ *
+ *----------------------------------------------------------------------
+ */
+Tcl_Obj *TclGetInnerContext(Tcl_Interp *interp,
+			    const unsigned char *pc,
+			    Tcl_Obj **tosPtr)
+{
+    int objc = 0, off = 0;
+    Tcl_Obj *result;
+
+    switch(*pc) {
+
+    case INST_STR_LEN:
+    case INST_LNOT:
+    case INST_BITNOT:
+    case INST_UMINUS:
+    case INST_UPLUS:
+    case INST_TRY_CVT_TO_NUMERIC:
+    case INST_EXPAND_STKTOP:
+    case INST_EXPR_STK:
+
+        objc = 1;
+        break;
+
+    case INST_LIST_IN:
+    case INST_LIST_NOT_IN:	/* Basic list containment operators. */
+    case INST_STR_EQ:
+    case INST_STR_NEQ:		/* String (in)equality check */
+    case INST_STR_CMP:		/* String compare. */
+    case INST_STR_INDEX:
+    case INST_STR_MATCH:
+    case INST_REGEXP:
+    case INST_EQ:
+    case INST_NEQ:
+    case INST_LT:
+    case INST_GT:
+    case INST_LE:
+    case INST_GE:
+    case INST_MOD:
+    case INST_LSHIFT:
+    case INST_RSHIFT:
+    case INST_BITOR:
+    case INST_BITXOR:
+    case INST_BITAND:
+    case INST_EXPON:
+    case INST_ADD:
+    case INST_SUB:
+    case INST_DIV:
+    case INST_MULT:
+        objc = 2;
+        break;
+
+    case INST_RETURN_STK:
+        /* early pop. TODO: dig out opt dict too :/ */
+        objc = 1;
+        break;
+
+    case INST_SYNTAX:
+    case INST_RETURN_IMM:
+        objc = 2;
+        break;
+
+   case INST_INVOKE_STK4:
+	objc = TclGetUInt4AtPtr(pc+1);
+        break;
+
+    case INST_INVOKE_STK1:
+	objc = TclGetUInt1AtPtr(pc+1);
+	break;
+
+
+
+    }
+    result = Tcl_NewListObj(objc + 1, NULL);
+    Tcl_ListObjAppendElement(NULL, result, Tcl_NewStringObj(tclInstructionTable[*pc].name, -1));
+    for(;objc>0;objc--) {
+        Tcl_ListObjAppendElement(NULL, result, tosPtr[1 - objc + off]);
+    }
+
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * PrintSourceToObj --
  *
  *	Appends a quoted representation of a string to a Tcl_Obj.
@@ -4349,5 +4438,7 @@ RecordByteCodeStats(
  * mode: c
  * c-basic-offset: 4
  * fill-column: 78
+ * tab-width: 8
+ * indent-tabs-mode: nil
  * End:
  */
Index: generic/tclCompile.h
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclCompile.h,v
retrieving revision 1.125
diff -u -p -r1.125 tclCompile.h
--- generic/tclCompile.h	29 Apr 2010 23:39:32 -0000	1.125
+++ generic/tclCompile.h	7 Jun 2010 23:37:24 -0000
@@ -981,6 +981,13 @@ MODULE_SCOPE void	TclVerifyLocalLiteralT
 #endif
 MODULE_SCOPE int	TclWordKnownAtCompileTime(Tcl_Token *tokenPtr,
 			    Tcl_Obj *valuePtr);
+MODULE_SCOPE void	TclLogCommandInfo(Tcl_Interp *interp,
+					  const char *script,
+					  const char *command, int length,
+					  const unsigned char *pc, Tcl_Obj **tosPtr); 
+MODULE_SCOPE Tcl_Obj	*TclGetInnerContext(Tcl_Interp *interp,
+					    const unsigned char *pc, Tcl_Obj **tosPtr); 
+
 
 /*
  *----------------------------------------------------------------
Index: generic/tclExecute.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclExecute.c,v
retrieving revision 1.486
diff -u -p -r1.486 tclExecute.c
--- generic/tclExecute.c	7 Jun 2010 21:24:59 -0000	1.486
+++ generic/tclExecute.c	7 Jun 2010 23:37:37 -0000
@@ -1971,6 +1971,11 @@ TclExecuteByteCode(
 				 * stack. */
     const unsigned char *pc = NULL;
 				/* The current program counter. */
+    const unsigned char *curPc = NULL;
+				/* Keep track of beginning of inst */
+    Tcl_Obj **curTosPtr = NULL ;
+				/* Keep track of tos */
+    
 
     /*
      * Transfer variables - needed only between opcodes, but not while
@@ -2174,6 +2179,9 @@ TclExecuteByteCode(
     }
   cleanup0:
 
+    curPc = pc;
+    curTosPtr = tosPtr;
+
 #ifdef TCL_COMPILE_DEBUG
     /*
      * Skip the stack depth check if an expansion is in progress.
@@ -6420,7 +6428,7 @@ TclExecuteByteCode(
 	if ((TRESULT == TCL_ERROR) && !(iPtr->flags & ERR_ALREADY_LOGGED)) {
 	    bytes = GetSrcInfoForPc(pc, codePtr, &length);
 	    DECACHE_STACK_INFO();
-	    Tcl_LogCommandInfo(interp, codePtr->source, bytes, bytes ? length : 0);
+	    TclLogCommandInfo(interp, codePtr->source, bytes, bytes ? length : 0, curPc, curTosPtr);
 	    CACHE_STACK_INFO();
 	}
 	iPtr->flags &= ~ERR_ALREADY_LOGGED;
Index: generic/tclInt.h
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclInt.h,v
retrieving revision 1.477
diff -u -p -r1.477 tclInt.h
--- generic/tclInt.h	28 May 2010 13:52:00 -0000	1.477
+++ generic/tclInt.h	7 Jun 2010 23:37:39 -0000
@@ -2166,6 +2166,7 @@ typedef struct Interp {
     Tcl_Obj *errorStack;	/* [info errorstack] value (as a Tcl_Obj). */
     Tcl_Obj *upLiteral;		/* "UP" literal for [info errorstack] */
     Tcl_Obj *callLiteral;	/* "CALL" literal for [info errorstack] */
+    Tcl_Obj *innerLiteral;	/* "INNER" literal for [info errorstack] */
     int resetErrorStack;        /* controls cleaning up of ::errorStack */
 
 #ifdef TCL_COMPILE_STATS
@@ -3105,6 +3106,8 @@ MODULE_SCOPE void	TclpThreadDeleteKey(vo
 MODULE_SCOPE void	TclpThreadSetMasterTSD(void *tsdKeyPtr, void *ptr);
 MODULE_SCOPE void *	TclpThreadGetMasterTSD(void *tsdKeyPtr);
 
+MODULE_SCOPE void	TclErrorStackResetIf(Tcl_Interp *interp, char *msg, int length);
+
 /*
  *----------------------------------------------------------------
  * Command procedures in the generic core:
Index: generic/tclNamesp.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclNamesp.c,v
retrieving revision 1.208
diff -u -p -r1.208 tclNamesp.c
--- generic/tclNamesp.c	7 Jun 2010 21:25:00 -0000	1.208
+++ generic/tclNamesp.c	7 Jun 2010 23:37:43 -0000
@@ -26,7 +26,7 @@
  */
 
 #include "tclInt.h"
-#include "tclCompile.h" /* just for NRCommand */
+#include "tclCompile.h" /* for NRCommand; and TclLogCommandInfo visibility */
 
 /*
  * Thread-local storage used to avoid having a global lock on data that is not
@@ -4845,31 +4845,36 @@ TclGetNamespaceChildTable(
 /*
  *----------------------------------------------------------------------
  *
- * Tcl_LogCommandInfo --
+ * TclLogCommandInfo --
  *
  *	This function is invoked after an error occurs in an interpreter. It
- *	adds information to iPtr->errorInfo field to describe the command that
- *	was being executed when the error occurred.
+ *	adds information to iPtr->errorInfo/errorStack fields to describe the
+ *	command that was being executed when the error occurred. When pc and
+ *	tosPtr are non-NULL, conveying a bytecode execution "inner context",
+ *	and the offending instruction is suitable, that inner context is
+ *	recorded in errorStack.
  *
  * Results:
  *	None.
  *
  * Side effects:
- *	Information about the command is added to errorInfo and the line
- *	number stored internally in the interpreter is set.
+ *	Information about the command is added to errorInfo/errorStack and the
+ *	line number stored internally in the interpreter is set.
  *
  *----------------------------------------------------------------------
  */
 
 void
-Tcl_LogCommandInfo(
+TclLogCommandInfo(
     Tcl_Interp *interp,		/* Interpreter in which to log information. */
     const char *script,		/* First character in script containing
 				 * command (must be <= command). */
     const char *command,	/* First character in command that generated
 				 * the error. */
-    int length)			/* Number of bytes in command (-1 means use
+    int length,			/* Number of bytes in command (-1 means use
 				 * all bytes up to first null byte). */
+    const unsigned char *pc,    /* current pc of bytecode execution context */
+    Tcl_Obj **tosPtr)           /* current stack of bytecode execution context */
 {
     register const char *p;
     Interp *iPtr = (Interp *) interp;
@@ -4954,6 +4959,18 @@ Tcl_LogCommandInfo(
 	Tcl_ListObjLength(interp, iPtr->errorStack, &len);
         /* reset while keeping the list intrep as much as possible */
         Tcl_ListObjReplace(interp, iPtr->errorStack, 0, len, 0, NULL);
+        if (pc != NULL) {
+            Tcl_Obj *innerContext;
+
+            innerContext = TclGetInnerContext(interp, pc, tosPtr);
+            if (innerContext != NULL) {
+                Tcl_ListObjAppendElement(NULL, iPtr->errorStack, iPtr->innerLiteral);
+                Tcl_ListObjAppendElement(NULL, iPtr->errorStack, innerContext);
+            }
+        } else if (command != NULL) {
+            Tcl_ListObjAppendElement(NULL, iPtr->errorStack, iPtr->innerLiteral);
+            Tcl_ListObjAppendElement(NULL, iPtr->errorStack, Tcl_NewStringObj(command, length));
+        }
     } 
 
     if (!iPtr->framePtr->objc) {
@@ -4973,6 +4990,80 @@ Tcl_LogCommandInfo(
 }
 
 /*
+ *----------------------------------------------------------------------
+ *
+ * TclErrorStackResetIf --
+ *
+ *      The TIP 348 reset/no-bc part of TLCI, for specific use by
+ *      TclCompileSyntaxError.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Reset errorstack if it needs be, and in that case remember the
+ *	passed-in error message as inner context.
+ *
+ *----------------------------------------------------------------------
+ */
+void TclErrorStackResetIf(Tcl_Interp *interp, char *msg, int length)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    if (Tcl_IsShared(iPtr->errorStack)) {
+        Tcl_Obj *newObj;
+            
+        newObj = Tcl_DuplicateObj(iPtr->errorStack);
+        Tcl_DecrRefCount(iPtr->errorStack);
+        Tcl_IncrRefCount(newObj);
+        iPtr->errorStack = newObj;
+    }
+    if (iPtr->resetErrorStack) {
+	int len;
+
+        iPtr->resetErrorStack = 0;
+	Tcl_ListObjLength(interp, iPtr->errorStack, &len);
+        /* reset while keeping the list intrep as much as possible */
+        Tcl_ListObjReplace(interp, iPtr->errorStack, 0, len, 0, NULL);
+        Tcl_ListObjAppendElement(NULL, iPtr->errorStack, iPtr->innerLiteral);
+        Tcl_ListObjAppendElement(NULL, iPtr->errorStack, Tcl_NewStringObj(msg, length));
+    } 
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LogCommandInfo --
+ *
+ *	This function is invoked after an error occurs in an interpreter. It
+ *	adds information to iPtr->errorInfo/errorStack fields to describe the
+ *	command that was being executed when the error occurred.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Information about the command is added to errorInfo/errorStack and the
+ *	line number stored internally in the interpreter is set.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LogCommandInfo(
+    Tcl_Interp *interp,		/* Interpreter in which to log information. */
+    const char *script,		/* First character in script containing
+				 * command (must be <= command). */
+    const char *command,	/* First character in command that generated
+				 * the error. */
+    int length)			/* Number of bytes in command (-1 means use
+				 * all bytes up to first null byte). */
+{
+    TclLogCommandInfo(interp, script, command, length, NULL, NULL);
+}
+
+
+/*
  * Local Variables:
  * mode: c
  * c-basic-offset: 4
