Another round of sentinel fixes for 8.6, NULL -> (char *)NULL

35 files changed, 217 insertions, 217 deletions

diff --git a/generic/tclBinary.c b/generic/tclBinary.c
index 8971334..cbcb4a1 100644
--- a/generic/tclBinary.c
+++ b/generic/tclBinary.c
@@ -2437,7 +2437,7 @@ BinaryDecodeHex(
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "invalid hexadecimal digit \"%c\" at position %d",
 	    ch, (int) (data - datastart - 1)));
-    Tcl_SetErrorCode(interp, "TCL", "BINARY", "DECODE", "INVALID", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "BINARY", "DECODE", "INVALID", (char *)NULL);
     return TCL_ERROR;
 }
 
diff --git a/generic/tclClock.c b/generic/tclClock.c
index 071f533..5d39de4 100644
--- a/generic/tclClock.c
+++ b/generic/tclClock.c
@@ -1064,7 +1064,7 @@ ConvertUTCToLocalUsingC(
     if ((Tcl_WideInt)tock != fields->seconds) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"number too large to represent as a Posix time", -1));
-	Tcl_SetErrorCode(interp, "CLOCK", "argTooLarge", NULL);
+	Tcl_SetErrorCode(interp, "CLOCK", "argTooLarge", (char *)NULL);
 	return TCL_ERROR;
     }
     TzsetIfNecessary();
@@ -1073,7 +1073,7 @@ ConvertUTCToLocalUsingC(
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"localtime failed (clock value may be too "
 		"large/small to represent)", -1));
-	Tcl_SetErrorCode(interp, "CLOCK", "localtimeFailed", NULL);
+	Tcl_SetErrorCode(interp, "CLOCK", "localtimeFailed", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -1925,7 +1925,7 @@ ClockParseformatargsObjCmd(
 	Tcl_WrongNumArgs(interp, 0, objv,
 		"clock format clockval ?-format string? "
 		"?-gmt boolean? ?-locale LOCALE? ?-timezone ZONE?");
-	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", NULL);
+	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -1972,7 +1972,7 @@ ClockParseformatargsObjCmd(
     if ((saw & (1 << CLOCK_FORMAT_GMT))
 	    && (saw & (1 << CLOCK_FORMAT_TIMEZONE))) {
 	Tcl_SetObjResult(interp, litPtr[LIT_CANNOT_USE_GMT_AND_TIMEZONE]);
-	Tcl_SetErrorCode(interp, "CLOCK", "gmtWithTimezone", NULL);
+	Tcl_SetErrorCode(interp, "CLOCK", "gmtWithTimezone", (char *)NULL);
 	return TCL_ERROR;
     }
     if (gmtFlag) {
diff --git a/generic/tclCmdAH.c b/generic/tclCmdAH.c
index a26254c..adbe9a6 100644
--- a/generic/tclCmdAH.c
+++ b/generic/tclCmdAH.c
@@ -2063,7 +2063,7 @@ PathFilesystemCmd(
     if (fsInfo == NULL) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj("unrecognised path", -1));
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "FILESYSTEM",
-		TclGetString(objv[1]), NULL);
+		TclGetString(objv[1]), (char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_SetObjResult(interp, fsInfo);
@@ -2213,7 +2213,7 @@ PathSplitCmd(
 		"could not read \"%s\": no such file or directory",
 		TclGetString(objv[1])));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PATHSPLIT", "NONESUCH",
-		NULL);
+		(char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_SetObjResult(interp, res);
@@ -2315,7 +2315,7 @@ FilesystemSeparatorCmd(
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "unrecognised path", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "FILESYSTEM",
-		    TclGetString(objv[1]), NULL);
+		    TclGetString(objv[1]), (char *)NULL);
 	    return TCL_ERROR;
 	}
 	Tcl_SetObjResult(interp, separatorObj);
@@ -2681,7 +2681,7 @@ TclNRForIterCallback(
 	Tcl_ResetResult(interp);
 	TclNewObj(boolObj);
 	TclNRAddCallback(interp, ForCondCallback, iterPtr, boolObj, NULL,
-		NULL);
+		(char *)NULL);
 	return Tcl_NRExprObj(interp, iterPtr->cond, boolObj);
     case TCL_BREAK:
 	result = TCL_OK;
diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index a6e9ffd..cfccd5e 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -1863,7 +1863,7 @@ StringMapCmd(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "bad option \"%s\": must be -nocase", string));
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "INDEX", "option",
-		    string, NULL);
+		    string, (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
diff --git a/generic/tclCompExpr.c b/generic/tclCompExpr.c
index 989ca79..313c51f 100644
--- a/generic/tclCompExpr.c
+++ b/generic/tclCompExpr.c
@@ -1439,7 +1439,7 @@ ParseExpr(
 		parsePtr->string, (numBytes < limit) ? "" : "..."));
 	if (errCode) {
 	    Tcl_SetErrorCode(interp, "TCL", "PARSE", "EXPR", errCode,
-		    subErrCode, NULL);
+		    subErrCode, (char *)NULL);
 	}
     }
 
diff --git a/generic/tclConfig.c b/generic/tclConfig.c
index 8fe8fc9..f00a568 100644
--- a/generic/tclConfig.c
+++ b/generic/tclConfig.c
@@ -230,7 +230,7 @@ QueryConfigObjCmd(
 
 	Tcl_SetObjResult(interp, Tcl_NewStringObj("package not known", -1));
 	Tcl_SetErrorCode(interp, "TCL", "FATAL", "PKGCFG_BASE",
-		Tcl_GetString(pkgName), NULL);
+		Tcl_GetString(pkgName), (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -245,7 +245,7 @@ QueryConfigObjCmd(
 		|| val == NULL) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj("key not known", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "CONFIG",
-		    Tcl_GetString(objv[2]), NULL);
+		    Tcl_GetString(objv[2]), (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -278,7 +278,7 @@ QueryConfigObjCmd(
 	if (!listPtr) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "insufficient memory to create list", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "MEMORY", (char *)NULL);
 	    return TCL_ERROR;
 	}
 
diff --git a/generic/tclDate.c b/generic/tclDate.c
index d3b6947..7e2aded 100644
--- a/generic/tclDate.c
+++ b/generic/tclDate.c
@@ -2792,12 +2792,12 @@ TclClockOldscanObjCmd(
     if (status == 1) {
 	Tcl_SetObjResult(interp, dateInfo.messages);
 	Tcl_DecrRefCount(dateInfo.messages);
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "PARSE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "PARSE", (char *)NULL);
 	return TCL_ERROR;
     } else if (status == 2) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj("memory exhausted", -1));
 	Tcl_DecrRefCount(dateInfo.messages);
-	Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "MEMORY", (char *)NULL);
 	return TCL_ERROR;
     } else if (status != 0) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj("Unknown status returned "
@@ -2805,7 +2805,7 @@ TclClockOldscanObjCmd(
 						  "report this error as a "
 						  "bug in Tcl.", -1));
 	Tcl_DecrRefCount(dateInfo.messages);
-	Tcl_SetErrorCode(interp, "TCL", "BUG", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "BUG", (char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_DecrRefCount(dateInfo.messages);
@@ -2813,31 +2813,31 @@ TclClockOldscanObjCmd(
     if (yyHaveDate > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one date in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveTime > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one time of day in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveZone > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one time zone in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveDay > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one weekday in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveOrdinalMonth > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one ordinal month in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
 
diff --git a/generic/tclDictObj.c b/generic/tclDictObj.c
index 3cd9f43..d67de7c 100644
--- a/generic/tclDictObj.c
+++ b/generic/tclDictObj.c
@@ -720,7 +720,7 @@ SetDictFromAny(
     if (interp != NULL) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"missing value to go with key", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DICTIONARY", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DICTIONARY", (char *)NULL);
     }
   errorInFindDictElement:
     DeleteChainTable(dict);
@@ -796,7 +796,7 @@ TclTraceDictPath(
 			    "key \"%s\" not known in dictionary",
 			    TclGetString(keyv[i])));
 		    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "DICT",
-			    TclGetString(keyv[i]), NULL);
+			    TclGetString(keyv[i]), (char *)NULL);
 		}
 		return NULL;
 	    }
@@ -1725,7 +1725,7 @@ DictGetCmd(
 		"key \"%s\" not known in dictionary",
 		TclGetString(objv[objc-1])));
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "DICT",
-		TclGetString(objv[objc-1]), NULL);
+		TclGetString(objv[objc-1]), (char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_SetObjResult(interp, valuePtr);
@@ -2517,7 +2517,7 @@ DictForNRCmd(
     if (varc != 2) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"must have exactly two variable names", -1));
-	Tcl_SetErrorCode(interp, "TCL", "SYNTAX", "dict", "for", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "SYNTAX", "dict", "for", (char *)NULL);
 	return TCL_ERROR;
     }
     searchPtr = (Tcl_DictSearch *)TclStackAlloc(interp, sizeof(Tcl_DictSearch));
@@ -2712,7 +2712,7 @@ DictMapNRCmd(
     if (varc != 2) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"must have exactly two variable names", -1));
-	Tcl_SetErrorCode(interp, "TCL", "SYNTAX", "dict", "map", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "SYNTAX", "dict", "map", (char *)NULL);
 	return TCL_ERROR;
     }
     storagePtr = (DictMapStorage *)TclStackAlloc(interp, sizeof(DictMapStorage));
@@ -3151,7 +3151,7 @@ DictFilterCmd(
 	if (varc != 2) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "must have exactly two variable names", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "SYNTAX", "dict", "filter", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "SYNTAX", "dict", "filter", (char *)NULL);
 	    return TCL_ERROR;
 	}
 	keyVarObj = varv[0];
diff --git a/generic/tclEncoding.c b/generic/tclEncoding.c
index bbcaeb9..e1f2536 100644
--- a/generic/tclEncoding.c
+++ b/generic/tclEncoding.c
@@ -1575,7 +1575,7 @@ OpenEncodingFileChannel(
     if ((NULL == chan) && (interp != NULL)) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"unknown encoding \"%s\"", name));
-	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENCODING", name, NULL);
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENCODING", name, (char *)NULL);
     }
     Tcl_DecrRefCount(fileNameObj);
     Tcl_DecrRefCount(searchPath);
@@ -1649,7 +1649,7 @@ LoadEncodingFile(
     if ((encoding == NULL) && (interp != NULL)) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"invalid encoding file \"%s\"", name));
-	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENCODING", name, NULL);
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENCODING", name, (char *)NULL);
     }
     Tcl_Close(NULL, chan);
 
diff --git a/generic/tclEvent.c b/generic/tclEvent.c
index 49880b6..99d5e0a 100644
--- a/generic/tclEvent.c
+++ b/generic/tclEvent.c
@@ -327,7 +327,7 @@ TclDefaultBgErrorHandlerObjCmd(
     if (result != TCL_OK || valuePtr == NULL) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"missing return option \"-level\"", -1));
-	Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "MISSING", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "MISSING", (char *)NULL);
 	return TCL_ERROR;
     }
     if (Tcl_GetIntFromObj(interp, valuePtr, &level) == TCL_ERROR) {
@@ -337,7 +337,7 @@ TclDefaultBgErrorHandlerObjCmd(
     if (result != TCL_OK || valuePtr == NULL) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"missing return option \"-code\"", -1));
-	Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "MISSING", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "MISSING", (char *)NULL);
 	return TCL_ERROR;
     }
     if (Tcl_GetIntFromObj(interp, valuePtr, &code) == TCL_ERROR) {
@@ -1425,7 +1425,7 @@ Tcl_VwaitObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"can't wait for variable \"%s\": would wait forever",
 		nameString));
-	Tcl_SetErrorCode(interp, "TCL", "EVENT", "NO_SOURCES", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "EVENT", "NO_SOURCES", (char *)NULL);
 	return TCL_ERROR;
     }
     if (!done) {
diff --git a/generic/tclFCmd.c b/generic/tclFCmd.c
index 56445b6..e550882 100644
--- a/generic/tclFCmd.c
+++ b/generic/tclFCmd.c
@@ -1080,7 +1080,7 @@ TclFileAttrsCmd(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "bad option \"%s\", there are no file attributes in this"
 		    " filesystem", TclGetString(objv[0])));
-	    Tcl_SetErrorCode(interp, "TCL","OPERATION","FATTR","NONE", NULL);
+	    Tcl_SetErrorCode(interp, "TCL","OPERATION","FATTR","NONE", (char *)NULL);
 	    goto end;
 	}
 
@@ -1107,7 +1107,7 @@ TclFileAttrsCmd(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "bad option \"%s\", there are no file attributes in this"
 		    " filesystem", TclGetString(objv[0])));
-	    Tcl_SetErrorCode(interp, "TCL","OPERATION","FATTR","NONE", NULL);
+	    Tcl_SetErrorCode(interp, "TCL","OPERATION","FATTR","NONE", (char *)NULL);
 	    goto end;
 	}
 
@@ -1123,7 +1123,7 @@ TclFileAttrsCmd(
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			"value for \"%s\" missing", TclGetString(objv[i])));
 		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "FATTR",
-			"NOVALUE", NULL);
+			"NOVALUE", (char *)NULL);
 		goto end;
 	    }
 	    if (Tcl_FSFileAttrsSet(interp, index, filePtr,
diff --git a/generic/tclFileName.c b/generic/tclFileName.c
index 7e24552..1fc89dc 100644
--- a/generic/tclFileName.c
+++ b/generic/tclFileName.c
@@ -1539,7 +1539,7 @@ Tcl_GlobObjCmd(
 	    badTypesArg:
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			"bad argument to \"-types\": %s",
-			TclGetString(look)));
+			Tcl_GetString(look)));
 		Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "BAD", (char *)NULL);
 		result = TCL_ERROR;
 		join = 0;
diff --git a/generic/tclGetDate.y b/generic/tclGetDate.y
index f73f9ce..3a55b8e 100644
--- a/generic/tclGetDate.y
+++ b/generic/tclGetDate.y
@@ -1013,12 +1013,12 @@ TclClockOldscanObjCmd(
     if (status == 1) {
 	Tcl_SetObjResult(interp, dateInfo.messages);
 	Tcl_DecrRefCount(dateInfo.messages);
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "PARSE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "PARSE", (char *)NULL);
 	return TCL_ERROR;
     } else if (status == 2) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj("memory exhausted", -1));
 	Tcl_DecrRefCount(dateInfo.messages);
-	Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "MEMORY", (char *)NULL);
 	return TCL_ERROR;
     } else if (status != 0) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj("Unknown status returned "
@@ -1026,7 +1026,7 @@ TclClockOldscanObjCmd(
 						  "report this error as a "
 						  "bug in Tcl.", -1));
 	Tcl_DecrRefCount(dateInfo.messages);
-	Tcl_SetErrorCode(interp, "TCL", "BUG", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "BUG", (char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_DecrRefCount(dateInfo.messages);
@@ -1034,31 +1034,31 @@ TclClockOldscanObjCmd(
     if (yyHaveDate > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one date in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveTime > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one time of day in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveZone > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one time zone in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveDay > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one weekday in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
     if (yyHaveOrdinalMonth > 1) {
 	Tcl_SetObjResult(interp,
 		Tcl_NewStringObj("more than one ordinal month in string", -1));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "DATE", "MULTIPLE", (char *)NULL);
 	return TCL_ERROR;
     }
 
diff --git a/generic/tclIOCmd.c b/generic/tclIOCmd.c
index cdcef10..0c8af09 100644
--- a/generic/tclIOCmd.c
+++ b/generic/tclIOCmd.c
@@ -450,7 +450,7 @@ Tcl_ReadObjCmd(
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			"expected non-negative integer but got \"%s\"",
 			TclGetString(objv[i])));
-		Tcl_SetErrorCode(interp, "TCL", "VALUE", "NUMBER", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "VALUE", "NUMBER", (char *)NULL);
 		return TCL_ERROR;
 	    }
 	    newline = 1;
@@ -1386,7 +1386,7 @@ AcceptCallbackProc(
 	Tcl_RegisterChannel(NULL, chan);
 
 	result = Tcl_VarEval(interp, script, " ", Tcl_GetChannelName(chan),
-		" ", address, " ", portBuf, NULL);
+		" ", address, " ", portBuf, (char *)NULL);
 	if (result != TCL_OK) {
 	    Tcl_BackgroundException(interp, result);
 	    Tcl_UnregisterChannel(interp, chan);
diff --git a/generic/tclInterp.c b/generic/tclInterp.c
index ad06293..c34cbbf 100644
--- a/generic/tclInterp.c
+++ b/generic/tclInterp.c
@@ -3118,7 +3118,7 @@ ChildMarkTrusted(
 		"permission denied: safe interpreter cannot mark trusted",
 		-1));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "UNSAFE",
-		NULL);
+		(char *)NULL);
 	return TCL_ERROR;
     }
     ((Interp *) childInterp)->flags &= ~SAFE_INTERP;
diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index b2d6228..f063599 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -168,7 +168,7 @@ AttemptNewList(
 		    "list creation failed: unable to alloc %u bytes",
 		    LIST_SIZE(objc)));
 	}
-	Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "MEMORY", (char *)NULL);
     }
     return listRepPtr;
 }
@@ -582,7 +582,7 @@ Tcl_ListObjAppendElement(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "max length of a Tcl list (%d elements) exceeded",
 		    LIST_MAX));
-	    Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "MEMORY", (char *)NULL);
 	}
 	return TCL_ERROR;
     }
@@ -1447,7 +1447,7 @@ TclLsetFlat(
 		Tcl_SetObjResult(interp,
 			Tcl_NewStringObj("list index out of range", -1));
 		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LSET",
-			"BADINDEX", NULL);
+			"BADINDEX", (char *)NULL);
 	    }
 	    result = TCL_ERROR;
 	    break;
@@ -1637,7 +1637,7 @@ TclListObjSetElement(
 		Tcl_SetObjResult(interp,
 			Tcl_NewStringObj("list index out of range", -1));
 		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LSET",
-			"BADINDEX", NULL);
+			"BADINDEX", (char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -1659,7 +1659,7 @@ TclListObjSetElement(
 	    Tcl_SetObjResult(interp,
 		    Tcl_NewStringObj("list index out of range", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LSET", "BADINDEX",
-		    NULL);
+		    (char *)NULL);
 	}
 	return TCL_ERROR;
     }
diff --git a/generic/tclLoad.c b/generic/tclLoad.c
index 28117f5..df9ef7d 100644
--- a/generic/tclLoad.c
+++ b/generic/tclLoad.c
@@ -185,7 +185,7 @@ Tcl_LoadObjCmd(
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"must specify either file name or package name", -1));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LOAD", "NOLIBRARY",
-		NULL);
+		(char *)NULL);
 	code = TCL_ERROR;
 	goto done;
     }
@@ -253,7 +253,7 @@ Tcl_LoadObjCmd(
 		    "file \"%s\" is already loaded for package \"%s\"",
 		    fullFileName, pkgPtr->packageName));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LOAD",
-		    "SPLITPERSONALITY", NULL);
+		    "SPLITPERSONALITY", (char *)NULL);
 	    code = TCL_ERROR;
 	    Tcl_MutexUnlock(&packageMutex);
 	    goto done;
@@ -290,7 +290,7 @@ Tcl_LoadObjCmd(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "package \"%s\" isn't loaded statically", packageName));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LOAD", "NOTSTATIC",
-		    NULL);
+		    (char *)NULL);
 	    code = TCL_ERROR;
 	    goto done;
 	}
@@ -349,7 +349,7 @@ Tcl_LoadObjCmd(
 			    "couldn't figure out package name for %s",
 			    fullFileName));
 		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LOAD",
-			    "WHATPACKAGE", NULL);
+			    "WHATPACKAGE", (char *)NULL);
 		    code = TCL_ERROR;
 		    goto done;
 		}
@@ -446,7 +446,7 @@ Tcl_LoadObjCmd(
 		    "can't use package in a safe interpreter: no"
 		    " %s_SafeInit procedure", pkgPtr->packageName));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LOAD", "UNSAFE",
-		    NULL);
+		    (char *)NULL);
 	    code = TCL_ERROR;
 	    goto done;
 	}
@@ -457,7 +457,7 @@ Tcl_LoadObjCmd(
 		    "can't attach package to interpreter: no %s_Init procedure",
 		    pkgPtr->packageName));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "LOAD", "ENTRYPOINT",
-		    NULL);
+		    (char *)NULL);
 	    code = TCL_ERROR;
 	    goto done;
 	}
@@ -608,7 +608,7 @@ Tcl_UnloadObjCmd(
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"must specify either file name or package name", -1));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "NOLIBRARY",
-		NULL);
+		(char *)NULL);
 	code = TCL_ERROR;
 	goto done;
     }
@@ -682,7 +682,7 @@ Tcl_UnloadObjCmd(
 		"package \"%s\" is loaded statically and cannot be unloaded",
 		packageName));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "STATIC",
-		NULL);
+		(char *)NULL);
 	code = TCL_ERROR;
 	goto done;
     }
@@ -694,7 +694,7 @@ Tcl_UnloadObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"file \"%s\" has never been loaded", fullFileName));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "NEVERLOADED",
-		NULL);
+		(char *)NULL);
 	code = TCL_ERROR;
 	goto done;
     }
@@ -724,7 +724,7 @@ Tcl_UnloadObjCmd(
 		"file \"%s\" has never been loaded in this interpreter",
 		fullFileName));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "NEVERLOADED",
-		NULL);
+		(char *)NULL);
 	code = TCL_ERROR;
 	goto done;
     }
@@ -741,7 +741,7 @@ Tcl_UnloadObjCmd(
 		    "file \"%s\" cannot be unloaded under a safe interpreter",
 		    fullFileName));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "CANNOT",
-		    NULL);
+		    (char *)NULL);
 	    code = TCL_ERROR;
 	    goto done;
 	}
@@ -752,7 +752,7 @@ Tcl_UnloadObjCmd(
 		    "file \"%s\" cannot be unloaded under a trusted interpreter",
 		    fullFileName));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "CANNOT",
-		    NULL);
+		    (char *)NULL);
 	    code = TCL_ERROR;
 	    goto done;
 	}
@@ -893,7 +893,7 @@ Tcl_UnloadObjCmd(
 		"file \"%s\" cannot be unloaded: unloading disabled",
 		fullFileName));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "UNLOAD", "DISABLED",
-		NULL);
+		(char *)NULL);
 	code = TCL_ERROR;
 #endif
     }
diff --git a/generic/tclOO.c b/generic/tclOO.c
index 86c4087..a7aeeeb 100644
--- a/generic/tclOO.c
+++ b/generic/tclOO.c
@@ -1773,7 +1773,7 @@ TclNewObjectInstanceCommon(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "can't create object \"%s\": command already exists with"
 		    " that name", nameStr));
-	    Tcl_SetErrorCode(interp, "TCL", "OO", "OVERWRITE_OBJECT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "OVERWRITE_OBJECT", (char *)NULL);
 	    return NULL;
 	}
     }
@@ -1827,7 +1827,7 @@ FinalizeAlloc(
     if (result != TCL_ERROR && Destructing(oPtr)) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"object deleted in constructor", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "STILLBORN", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "STILLBORN", (char *)NULL);
 	result = TCL_ERROR;
     }
     if (result != TCL_OK) {
@@ -1896,7 +1896,7 @@ Tcl_CopyObjectInstance(
     if (IsRootClass(oPtr)) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"may not clone the class of classes", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "CLONING_CLASS", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "CLONING_CLASS", (char *)NULL);
 	return NULL;
     }
 
@@ -2587,7 +2587,7 @@ TclOOObjectCmdCore(
 		    "impossible to invoke method \"%s\": no defined method or"
 		    " unknown method", TclGetString(methodNamePtr)));
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD_MAPPED",
-		    TclGetString(methodNamePtr), NULL);
+		    TclGetString(methodNamePtr), (char *)NULL);
 	    return TCL_ERROR;
 	}
     } else {
@@ -2603,7 +2603,7 @@ TclOOObjectCmdCore(
 		    "impossible to invoke method \"%s\": no defined method or"
 		    " unknown method", TclGetString(methodNamePtr)));
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD",
-		    TclGetString(methodNamePtr), NULL);
+		    TclGetString(methodNamePtr), (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
@@ -2630,7 +2630,7 @@ TclOOObjectCmdCore(
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "no valid method implementation", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD",
-		    TclGetString(methodNamePtr), NULL);
+		    TclGetString(methodNamePtr), (char *)NULL);
 	    TclOODeleteContext(contextPtr);
 	    return TCL_ERROR;
 	}
@@ -2711,7 +2711,7 @@ Tcl_ObjectContextInvokeNext(
 
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"no next %s implementation", methodType));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "NOTHING_NEXT", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "NOTHING_NEXT", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -2780,7 +2780,7 @@ TclNRObjectContextInvokeNext(
 
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"no next %s implementation", methodType));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "NOTHING_NEXT", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "NOTHING_NEXT", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -2859,7 +2859,7 @@ Tcl_GetObjectFromObj(
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "%s does not refer to an object", TclGetString(objPtr)));
     Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "OBJECT", TclGetString(objPtr),
-	    NULL);
+	    (char *)NULL);
     return NULL;
 }
 
diff --git a/generic/tclOOBasic.c b/generic/tclOOBasic.c
index e746b64..40a70c2 100644
--- a/generic/tclOOBasic.c
+++ b/generic/tclOOBasic.c
@@ -169,7 +169,7 @@ TclOO_Class_Create(
 
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"object \"%s\" is not a class", TclGetString(cmdnameObj)));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -187,7 +187,7 @@ TclOO_Class_Create(
     if (len == 0) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"object name must not be empty", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -234,7 +234,7 @@ TclOO_Class_CreateNs(
 
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"object \"%s\" is not a class", TclGetString(cmdnameObj)));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -252,7 +252,7 @@ TclOO_Class_CreateNs(
     if (len == 0) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"object name must not be empty", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", (char *)NULL);
 	return TCL_ERROR;
     }
     nsName = Tcl_GetStringFromObj(
@@ -260,7 +260,7 @@ TclOO_Class_CreateNs(
     if (len == 0) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"namespace name must not be empty", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -305,7 +305,7 @@ TclOO_Class_New(
 
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"object \"%s\" is not a class", TclGetString(cmdnameObj)));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -538,7 +538,7 @@ TclOO_Object_Unknown(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"object \"%s\" has no %s", TclGetString(tmpBuf), piece));
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD",
-		TclGetString(objv[skip]), NULL);
+		TclGetString(objv[skip]), (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -557,7 +557,7 @@ TclOO_Object_Unknown(
     ckfree(methodNames);
     Tcl_SetObjResult(interp, errorMsg);
     Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD",
-	    TclGetString(objv[skip]), NULL);
+	    TclGetString(objv[skip]), (char *)NULL);
     return TCL_ERROR;
 }
 
@@ -614,7 +614,7 @@ TclOO_Object_LinkVar(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "variable name \"%s\" illegal: must not contain namespace"
 		    " separator", varName));
-	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "INVERTED", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "INVERTED", (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -643,7 +643,7 @@ TclOO_Object_LinkVar(
 
 	    TclVarErrMsg(interp, varName, NULL, "define",
 		    "name refers to an element in an array");
-	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT", (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -718,7 +718,7 @@ TclOO_Object_VarName(
 	    TCL_NAMESPACE_ONLY|TCL_LEAVE_ERR_MSG, "refer to", 1, 1, &aryVar);
     Tcl_DecrRefCount(varNamePtr);
     if (varPtr == NULL) {
-	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARIABLE", arg, NULL);
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARIABLE", arg, (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -789,7 +789,7 @@ TclOONextObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"%s may only be called from inside a method",
 		TclGetString(objv[0])));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
 	return TCL_ERROR;
     }
     context = framePtr->clientData;
@@ -829,7 +829,7 @@ TclOONextToObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"%s may only be called from inside a method",
 		TclGetString(objv[0])));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
 	return TCL_ERROR;
     }
     contextPtr = framePtr->clientData;
@@ -850,7 +850,7 @@ TclOONextToObjCmd(
     if (classPtr == NULL) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"\"%s\" is not a class", TclGetString(objv[1])));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_REQUIRED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_REQUIRED", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -899,14 +899,14 @@ TclOONextToObjCmd(
 		    "%s implementation by \"%s\" not reachable from here",
 		    methodType, TclGetString(objv[1])));
 	    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_REACHABLE",
-		    NULL);
+		    (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "%s has no non-filter implementation by \"%s\"",
 	    methodType, TclGetString(objv[1])));
-    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_THERE", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_THERE", (char *)NULL);
     return TCL_ERROR;
 }
 
@@ -969,7 +969,7 @@ TclOOSelfObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"%s may only be called from inside a method",
 		TclGetString(objv[0])));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -1004,7 +1004,7 @@ TclOOSelfObjCmd(
 	if (clsPtr == NULL) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "method not defined by a class", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -1025,7 +1025,7 @@ TclOOSelfObjCmd(
 	if (!CurrentlyInvoked(contextPtr).isFilter) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "not inside a filtering context", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", (char *)NULL);
 	    return TCL_ERROR;
 	} else {
 	    struct MInvoke *miPtr = &CurrentlyInvoked(contextPtr);
@@ -1051,7 +1051,7 @@ TclOOSelfObjCmd(
 		!(framePtr->callerVarPtr->isProcCallFrame & FRAME_IS_METHOD)){
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "caller is not an object", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
 	    return TCL_ERROR;
 	} else {
 	    CallContext *callerPtr = framePtr->callerVarPtr->clientData;
@@ -1119,7 +1119,7 @@ TclOOSelfObjCmd(
 	if (!CurrentlyInvoked(contextPtr).isFilter) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "not inside a filtering context", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", (char *)NULL);
 	    return TCL_ERROR;
 	} else {
 	    Method *mPtr;
diff --git a/generic/tclOOMethod.c b/generic/tclOOMethod.c
index 5cff201..5633130 100644
--- a/generic/tclOOMethod.c
+++ b/generic/tclOOMethod.c
@@ -845,7 +845,7 @@ PushMethodCallFrame(
 
     pmPtr->procPtr->cmdPtr = &pmPtr->cmd;
     if (pmPtr->procPtr->bodyPtr->typePtr == &tclByteCodeType) {
-	ByteCode *codePtr =
+	ByteCode *codePtr = (ByteCode *)
 		pmPtr->procPtr->bodyPtr->internalRep.twoPtrValue.ptr1;
 
 	codePtr->nsPtr = nsPtr;
@@ -1356,7 +1356,7 @@ TclOONewForwardInstanceMethod(
     if (prefixLen < 1) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"method forward prefix must be non-empty", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "BAD_FORWARD", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "BAD_FORWARD", (char *)NULL);
 	return NULL;
     }
 
@@ -1395,7 +1395,7 @@ TclOONewForwardMethod(
     if (prefixLen < 1) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"method forward prefix must be non-empty", -1));
-	Tcl_SetErrorCode(interp, "TCL", "OO", "BAD_FORWARD", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "OO", "BAD_FORWARD", (char *)NULL);
 	return NULL;
     }
 
diff --git a/generic/tclObj.c b/generic/tclObj.c
index 284a431..35c62c3 100644
--- a/generic/tclObj.c
+++ b/generic/tclObj.c
@@ -976,7 +976,7 @@ Tcl_ConvertToType(
 	if (interp) {
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "can't convert value to type %s", typePtr->name));
-	    Tcl_SetErrorCode(interp, "TCL", "API_ABUSE", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "API_ABUSE", (char *)NULL);
 	}
 	return TCL_ERROR;
     }
@@ -1996,7 +1996,7 @@ TclSetBooleanFromAny(
 	Tcl_AppendLimitedToObj(msg, str, length, 50, "");
 	Tcl_AppendToObj(msg, "\"", -1);
 	Tcl_SetObjResult(interp, msg);
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "BOOLEAN", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "BOOLEAN", (char *)NULL);
     }
     return TCL_ERROR;
 }
@@ -2285,7 +2285,7 @@ Tcl_GetDoubleFromObj(
 		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 			    "floating point value is Not a Number", -1));
                     Tcl_SetErrorCode(interp, "TCL", "VALUE", "DOUBLE", "NAN",
-                            NULL);
+                            (char *)NULL);
 		}
 		return TCL_ERROR;
 	    }
@@ -2508,7 +2508,7 @@ Tcl_GetIntFromObj(
 	if (interp != NULL) {
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "expected integer but got \"%s\"", Tcl_GetString(objPtr)));
-	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", (char *)NULL);
 	}
 	return TCL_ERROR;
     }
@@ -2518,7 +2518,7 @@ Tcl_GetIntFromObj(
 	    const char *s =
 		    "integer value too large to represent";
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(s, -1));
-	    Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, NULL);
+	    Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, (char *)NULL);
 	}
 	return TCL_ERROR;
     }
@@ -2797,7 +2797,7 @@ Tcl_GetLongFromObj(
                 Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                         "expected integer but got \"%s\"",
                         TclGetString(objPtr)));
-		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", (char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -2839,7 +2839,7 @@ Tcl_GetLongFromObj(
 		Tcl_Obj *msg = Tcl_NewStringObj(s, -1);
 
 		Tcl_SetObjResult(interp, msg);
-		Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, NULL);
+		Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, (char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -3093,7 +3093,7 @@ Tcl_GetWideIntFromObj(
                 Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                         "expected integer but got \"%s\"",
                         TclGetString(objPtr)));
-		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", (char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -3130,7 +3130,7 @@ Tcl_GetWideIntFromObj(
 		Tcl_Obj *msg = Tcl_NewStringObj(s, -1);
 
 		Tcl_SetObjResult(interp, msg);
-		Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, NULL);
+		Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, (char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -3398,7 +3398,7 @@ GetBignumFromObj(
 		    if (interp != NULL) {
 			Tcl_SetObjResult(interp, Tcl_NewStringObj(
 				"insufficient memory to unpack bignum", -1));
-			Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+			Tcl_SetErrorCode(interp, "TCL", "MEMORY", (char *)NULL);
 		    }
 		    return TCL_ERROR;
 		}
@@ -3429,7 +3429,7 @@ GetBignumFromObj(
                 Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                         "expected integer but got \"%s\"",
                         TclGetString(objPtr)));
-		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", (char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
diff --git a/generic/tclPathObj.c b/generic/tclPathObj.c
index f5571e2..a17c343 100644
--- a/generic/tclPathObj.c
+++ b/generic/tclPathObj.c
@@ -1523,7 +1523,7 @@ MakePathFromNormalized(
 		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 			    "can't find object string representation", -1));
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "PATH", "WTF",
-			    NULL);
+			    (char *)NULL);
 		}
 		return TCL_ERROR;
 	    }
@@ -2397,7 +2397,7 @@ SetFsPathFromAny(
 			    "couldn't find HOME environment variable to"
 			    " expand path", -1));
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "PATH",
-			    "HOMELESS", NULL);
+			    "HOMELESS", (char *)NULL);
 		}
 		return TCL_ERROR;
 	    }
@@ -2422,7 +2422,7 @@ SetFsPathFromAny(
 		    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			    "user \"%s\" doesn't exist", expandedUser));
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "PATH", "NOUSER",
-			    NULL);
+			    (char *)NULL);
 		}
 		Tcl_DStringFree(&userName);
 		Tcl_DStringFree(&temp);
diff --git a/generic/tclPipe.c b/generic/tclPipe.c
index 2c6f99b..676ee3a 100644
--- a/generic/tclPipe.c
+++ b/generic/tclPipe.c
@@ -327,7 +327,7 @@ TclCleanupChildren(
 	    if (WIFEXITED(waitStatus)) {
 		if (interp != NULL) {
 		    snprintf(msg2, sizeof(msg2), "%u", WEXITSTATUS(waitStatus));
-		    Tcl_SetErrorCode(interp, "CHILDSTATUS", msg1, msg2, NULL);
+		    Tcl_SetErrorCode(interp, "CHILDSTATUS", msg1, msg2, (char *)NULL);
 		}
 		abnormalExit = 1;
 	    } else if (interp != NULL) {
@@ -336,20 +336,20 @@ TclCleanupChildren(
 		if (WIFSIGNALED(waitStatus)) {
 		    p = Tcl_SignalMsg(WTERMSIG(waitStatus));
 		    Tcl_SetErrorCode(interp, "CHILDKILLED", msg1,
-			    Tcl_SignalId(WTERMSIG(waitStatus)), p, NULL);
+			    Tcl_SignalId(WTERMSIG(waitStatus)), p, (char *)NULL);
 		    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			    "child killed: %s\n", p));
 		} else if (WIFSTOPPED(waitStatus)) {
 		    p = Tcl_SignalMsg(WSTOPSIG(waitStatus));
 		    Tcl_SetErrorCode(interp, "CHILDSUSP", msg1,
-			    Tcl_SignalId(WSTOPSIG(waitStatus)), p, NULL);
+			    Tcl_SignalId(WSTOPSIG(waitStatus)), p, (char *)NULL);
 		    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			    "child suspended: %s\n", p));
 		} else {
 		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 			    "child wait status didn't make sense\n", -1));
 		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "EXEC",
-			    "ODDWAITRESULT", msg1, NULL);
+			    "ODDWAITRESULT", msg1, (char *)NULL);
 		}
 	    }
 	}
diff --git a/generic/tclPkg.c b/generic/tclPkg.c
index 7e8db0e..8bce8b5 100644
--- a/generic/tclPkg.c
+++ b/generic/tclPkg.c
@@ -174,7 +174,7 @@ Tcl_PkgProvideEx(
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "conflicting versions provided for package \"%s\": %s, then %s",
 	    name, TclGetString(pkgPtr->version), version));
-    Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "VERSIONCONFLICT", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "VERSIONCONFLICT", (char *)NULL);
     return TCL_ERROR;
 }
 
@@ -306,7 +306,7 @@ Tcl_PkgRequireEx(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"Cannot load package \"%s\" in standalone executable:"
 		" This package is not compiled with stub support", name));
-	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "UNSTUBBED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "UNSTUBBED", (char *)NULL);
 	return NULL;
     }
 
@@ -326,7 +326,7 @@ Tcl_PkgRequireEx(
 	}
 	ov = Tcl_NewStringObj(version, -1);
 	if (exact) {
-	    Tcl_AppendStringsToObj(ov, "-", version, NULL);
+	    Tcl_AppendStringsToObj(ov, "-", version, (char *)NULL);
 	}
 	Tcl_IncrRefCount(ov);
 	if (Tcl_PkgRequireProc(interp, name, 1, &ov, clientDataPtr) == TCL_OK) {
@@ -432,7 +432,7 @@ PkgRequireCoreStep2(ClientData data[], Tcl_Interp *interp, int result) {
     if ((result != TCL_OK) && (result != TCL_ERROR)) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"bad return code: %d", result));
-	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "BADRESULT", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "BADRESULT", (char *)NULL);
 	result = TCL_ERROR;
     }
     if (result == TCL_ERROR) {
@@ -458,7 +458,7 @@ PkgRequireCoreFinal(ClientData data[], Tcl_Interp *interp, int result) {
     if (reqPtr->pkgPtr->version == NULL) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"can't find package %s", name));
-	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "UNFOUND", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "UNFOUND", (char *)NULL);
 	AddRequirementsToResult(interp, reqc, reqv);
 	return TCL_ERROR;
     }
@@ -479,7 +479,7 @@ PkgRequireCoreFinal(ClientData data[], Tcl_Interp *interp, int result) {
 		    "version conflict for package \"%s\": have %s, need",
 		    name, TclGetString(reqPtr->pkgPtr->version)));
 	    Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "VERSIONCONFLICT",
-		    NULL);
+		    (char *)NULL);
 	    AddRequirementsToResult(interp, reqc, reqv);
 	    return TCL_ERROR;
 	}
@@ -525,7 +525,7 @@ SelectPackage(ClientData data[], Tcl_Interp *interp, int result) {
 		" attempt to provide %s %s requires %s",
 		name, (char *) pkgPtr->clientData, name));
 	AddRequirementsToResult(interp, reqc, reqv);
-	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "CIRCULARITY", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "CIRCULARITY", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -685,7 +685,7 @@ SelectPackageFinal(ClientData data[], Tcl_Interp *interp, int result) {
 		    " no version of package %s provided",
 		    name, versionToProvide, name));
 	    Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "UNPROVIDED",
-		    NULL);
+		    (char *)NULL);
 	} else {
 	    char *pvi, *vi;
 
@@ -709,7 +709,7 @@ SelectPackageFinal(ClientData data[], Tcl_Interp *interp, int result) {
 			    name, versionToProvide,
 			    name, TclGetString(reqPtr->pkgPtr->version)));
 		    Tcl_SetErrorCode(interp, "TCL", "PACKAGE",
-			    "WRONGPROVIDE", NULL);
+			    "WRONGPROVIDE", (char *)NULL);
 		}
 	    }
 	}
@@ -721,7 +721,7 @@ SelectPackageFinal(ClientData data[], Tcl_Interp *interp, int result) {
 		"attempt to provide package %s %s failed:"
 		" bad return code: %s",
 		name, versionToProvide, TclGetString(codePtr)));
-	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "BADRESULT", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "PACKAGE", "BADRESULT", (char *)NULL);
 	TclDecrRefCount(codePtr);
 	result = TCL_ERROR;
     }
@@ -827,7 +827,7 @@ Tcl_PkgPresentEx(
 
 	    if (foundVersion == NULL) {
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "PACKAGE", name,
-			NULL);
+			(char *)NULL);
 	    }
 	    return foundVersion;
 	}
@@ -840,7 +840,7 @@ Tcl_PkgPresentEx(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"package %s is not present", name));
     }
-    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "PACKAGE", name, NULL);
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "PACKAGE", name, (char *)NULL);
     return NULL;
 }
 
@@ -1508,7 +1508,7 @@ CheckVersionAndConvert(
     ckfree(ibuf);
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "expected version number but got \"%s\"", string));
-    Tcl_SetErrorCode(interp, "TCL", "VALUE", "VERSION", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "VALUE", "VERSION", (char *)NULL);
     return TCL_ERROR;
 }
 
@@ -1771,7 +1771,7 @@ CheckRequirement(
 
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"expected versionMin-versionMax but got \"%s\"", string));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "VERSIONRANGE", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "VERSIONRANGE", (char *)NULL);
 	return TCL_ERROR;
     }
 
diff --git a/generic/tclProc.c b/generic/tclProc.c
index 80d4c32..70cfbda 100644
--- a/generic/tclProc.c
+++ b/generic/tclProc.c
@@ -148,14 +148,14 @@ Tcl_ProcObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"can't create procedure \"%s\": unknown namespace",
 		procName));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "COMMAND", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "COMMAND", (char *)NULL);
 	return TCL_ERROR;
     }
     if (simpleName == NULL) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"can't create procedure \"%s\": bad procedure name",
 		procName));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "COMMAND", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "COMMAND", (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -463,7 +463,7 @@ TclCreateProc(
 		    "precompiled header expects %d", procName, numArgs,
 		    procPtr->numArgs));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-		    "BYTECODELIES", NULL);
+		    "BYTECODELIES", (char *)NULL);
 	    goto procError;
 	}
 	localPtr = procPtr->firstLocalPtr;
@@ -493,14 +493,14 @@ TclCreateProc(
 	    Tcl_AppendToObj(errorObj, "\"", -1);
 	    Tcl_SetObjResult(interp, errorObj);
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-		    "FORMALARGUMENTFORMAT", NULL);
+		    "FORMALARGUMENTFORMAT", (char *)NULL);
 	    goto procError;
 	}
 	if ((fieldCount == 0) || (Tcl_GetCharLength(fieldValues[0]) == 0)) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "argument with no name", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-		    "FORMALARGUMENTFORMAT", NULL);
+		    "FORMALARGUMENTFORMAT", (char *)NULL);
 	    goto procError;
 	}
 
@@ -517,7 +517,7 @@ TclCreateProc(
 			    "formal parameter \"%s\" is an array element",
 			    TclGetString(fieldValues[0])));
 		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-			    "FORMALARGUMENTFORMAT", NULL);
+			    "FORMALARGUMENTFORMAT", (char *)NULL);
 		    goto procError;
 		}
 	    } else if (p[0] == ':' && p[1] == ':') {
@@ -527,7 +527,7 @@ TclCreateProc(
 		Tcl_AppendToObj(errorObj, "\" is not a simple name", -1);
 		Tcl_SetObjResult(interp, errorObj);
 		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-			"FORMALARGUMENTFORMAT", NULL);
+			"FORMALARGUMENTFORMAT", (char *)NULL);
 		goto procError;
 	    }
 	    p++;
@@ -555,7 +555,7 @@ TclCreateProc(
 			"procedure \"%s\": formal parameter %d is "
 			"inconsistent with precompiled body", procName, i));
 		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-			"BYTECODELIES", NULL);
+			"BYTECODELIES", (char *)NULL);
 		goto procError;
 	    }
 
@@ -580,7 +580,7 @@ TclCreateProc(
 			"default value inconsistent with precompiled body", -1);
 		    Tcl_SetObjResult(interp, errorObj);
 		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-			    "BYTECODELIES", NULL);
+			    "BYTECODELIES", (char *)NULL);
 		    goto procError;
 		}
 	    }
@@ -731,7 +731,7 @@ TclGetFrame(
 
   levelError:
     Tcl_SetObjResult(interp, Tcl_ObjPrintf("bad level \"%s\"", name));
-    Tcl_SetErrorCode(interp, "TCL", "VALUE", "STACKLEVEL", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "VALUE", "STACKLEVEL", (char *)NULL);
     return -1;
 }
 
@@ -833,7 +833,7 @@ TclObjGetFrame(
     }
 
     Tcl_SetObjResult(interp, Tcl_ObjPrintf("bad level \"%s\"", name));
-    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "LEVEL", name, NULL);
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "LEVEL", name, (char *)NULL);
     return -1;
 }
 
@@ -1087,7 +1087,7 @@ ProcWrongNumArgs(
 
 	    if (defPtr->value.objPtr != NULL) {
 		TclNewObj(argObj);
-		Tcl_AppendStringsToObj(argObj, "?", TclGetString(namePtr), "?", NULL);
+		Tcl_AppendStringsToObj(argObj, "?", TclGetString(namePtr), "?", (char *)NULL);
 	    } else if (defPtr->flags & VAR_IS_ARGS) {
 		numArgs--;
 		final = "?arg ...?";
@@ -1859,7 +1859,7 @@ InterpProcNR2(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"invoked \"%s\" outside of a loop",
 		((result == TCL_BREAK) ? "break" : "continue")));
-	Tcl_SetErrorCode(interp, "TCL", "RESULT", "UNEXPECTED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "RESULT", "UNEXPECTED", (char *)NULL);
 	result = TCL_ERROR;
 
 	/* FALLTHRU */
@@ -1941,7 +1941,7 @@ TclProcCompileProc(
 		Tcl_SetObjResult(interp, Tcl_NewStringObj(
 			"a precompiled script jumped interps", -1));
 		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "PROC",
-			"CROSSINTERPBYTECODE", NULL);
+			"CROSSINTERPBYTECODE", (char *)NULL);
 		return TCL_ERROR;
 	    }
 	    codePtr->compileEpoch = iPtr->compileEpoch;
@@ -2446,7 +2446,7 @@ SetLambdaFromAny(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"can't interpret \"%s\" as a lambda expression",
 		TclGetString(objPtr)));
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "LAMBDA", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "LAMBDA", (char *)NULL);
 	return TCL_ERROR;
     }
 
diff --git a/generic/tclRegexp.c b/generic/tclRegexp.c
index 3259b48..9620bb9 100644
--- a/generic/tclRegexp.c
+++ b/generic/tclRegexp.c
@@ -732,7 +732,7 @@ TclRegError(
 
     snprintf(cbuf, sizeof(cbuf), "%d", status);
     (void) TclReError(REG_ITOA, cbuf, sizeof(cbuf));
-    Tcl_SetErrorCode(interp, "REGEXP", cbuf, buf, NULL);
+    Tcl_SetErrorCode(interp, "REGEXP", cbuf, buf, (char *)NULL);
 }
 
 /*
diff --git a/generic/tclResult.c b/generic/tclResult.c
index 4b8775a..7364f3f 100644
--- a/generic/tclResult.c
+++ b/generic/tclResult.c
@@ -1334,7 +1334,7 @@ TclProcessReturn(
 	if (valuePtr != NULL) {
 	    Tcl_SetObjErrorCode(interp, valuePtr);
 	} else {
-	    Tcl_SetErrorCode(interp, "NONE", NULL);
+	    Tcl_SetErrorCode(interp, "NONE", (char *)NULL);
 	}
 
 	Tcl_DictObjGet(NULL, iPtr->returnOpts, keys[KEY_ERRORLINE],
@@ -1416,7 +1416,7 @@ TclMergeReturnOptions(
                         "bad %s value: expected dictionary but got \"%s\"",
                         compare, TclGetString(objv[1])));
 		Tcl_SetErrorCode(interp, "TCL", "RESULT", "ILLEGAL_OPTIONS",
-			NULL);
+			(char *)NULL);
 		goto error;
 	    }
 
@@ -1465,7 +1465,7 @@ TclMergeReturnOptions(
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                     "bad -level value: expected non-negative integer but got"
                     " \"%s\"", TclGetString(valuePtr)));
-	    Tcl_SetErrorCode(interp, "TCL", "RESULT", "ILLEGAL_LEVEL", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "RESULT", "ILLEGAL_LEVEL", (char *)NULL);
 	    goto error;
 	}
 	Tcl_DictObjRemove(NULL, returnOpts, keys[KEY_LEVEL]);
@@ -1488,7 +1488,7 @@ TclMergeReturnOptions(
                     "bad -errorcode value: expected a list but got \"%s\"",
                     TclGetString(valuePtr)));
 	    Tcl_SetErrorCode(interp, "TCL", "RESULT", "ILLEGAL_ERRORCODE",
-		    NULL);
+		    (char *)NULL);
 	    goto error;
 	}
     }
@@ -1510,7 +1510,7 @@ TclMergeReturnOptions(
                     "bad -errorstack value: expected a list but got \"%s\"",
                     TclGetString(valuePtr)));
 	    Tcl_SetErrorCode(interp, "TCL", "RESULT", "NONLIST_ERRORSTACK",
-                    NULL);
+                    (char *)NULL);
 	    goto error;
 	}
         if (length % 2) {
@@ -1522,7 +1522,7 @@ TclMergeReturnOptions(
                     "forbidden odd-sized list for -errorstack: \"%s\"",
 		    TclGetString(valuePtr)));
 	    Tcl_SetErrorCode(interp, "TCL", "RESULT",
-                    "ODDSIZEDLIST_ERRORSTACK", NULL);
+                    "ODDSIZEDLIST_ERRORSTACK", (char *)NULL);
 	    goto error;
         }
     }
@@ -1675,7 +1675,7 @@ Tcl_SetReturnOptions(
 	    || (objc % 2)) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                 "expected dict but got \"%s\"", TclGetString(options)));
-	Tcl_SetErrorCode(interp, "TCL", "RESULT", "ILLEGAL_OPTIONS", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "RESULT", "ILLEGAL_OPTIONS", (char *)NULL);
 	code = TCL_ERROR;
     } else if (TCL_ERROR == TclMergeReturnOptions(interp, objc, objv,
 	    &mergedOpts, &code, &level)) {
diff --git a/generic/tclScan.c b/generic/tclScan.c
index 2861e0b..80f0f77 100644
--- a/generic/tclScan.c
+++ b/generic/tclScan.c
@@ -425,7 +425,7 @@ ValidateFormat(
 	    if (flags & SCAN_BIG) {
 		Tcl_SetObjResult(interp, Tcl_NewStringObj(
 			"unsigned bignum scans are invalid", -1));
-		Tcl_SetErrorCode(interp, "TCL", "FORMAT", "BADUNSIGNED",NULL);
+		Tcl_SetErrorCode(interp, "TCL", "FORMAT", "BADUNSIGNED", (char *)NULL);
 		goto error;
 	    }
 	    break;
diff --git a/generic/tclStrToD.c b/generic/tclStrToD.c
index a5d9ad1..432d11b 100644
--- a/generic/tclStrToD.c
+++ b/generic/tclStrToD.c
@@ -1481,7 +1481,7 @@ TclParseNumber(
 		Tcl_AppendToObj(msg, " (looks like invalid octal number)", -1);
 	    }
 	    Tcl_SetObjResult(interp, msg);
-	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "NUMBER", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "NUMBER", (char *)NULL);
 	}
     }
 
@@ -4693,7 +4693,7 @@ Tcl_InitBignumFromDouble(
 	    const char *s = "integer value too large to represent";
 
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(s, -1));
-	    Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, NULL);
+	    Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, (char *)NULL);
 	}
 	return TCL_ERROR;
     }
diff --git a/generic/tclTest.c b/generic/tclTest.c
index 2fd6714..491fea0 100644
--- a/generic/tclTest.c
+++ b/generic/tclTest.c
@@ -1397,7 +1397,7 @@ CreatedCommandProc(
 	    &info);
     if (!found) {
 	Tcl_AppendResult(interp, "CreatedCommandProc could not get command info for test_ns_basic::createdcommand",
-		NULL);
+		(char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_AppendResult(interp, "CreatedCommandProc in ",
@@ -1418,7 +1418,7 @@ CreatedCommandProc2(
     found = Tcl_GetCommandInfo(interp, "value:at:", &info);
     if (!found) {
 	Tcl_AppendResult(interp, "CreatedCommandProc2 could not get command info for test_ns_basic::createdcommand",
-		NULL);
+		(char *)NULL);
 	return TCL_ERROR;
     }
     Tcl_AppendResult(interp, "CreatedCommandProc2 in ",
@@ -1769,7 +1769,7 @@ TestdstringCmd(
 	} else {
 	    Tcl_AppendResult(interp, "bad gresult option \"", argv[2],
 		    "\": must be staticsmall, staticlarge, free, or special",
-		    NULL);
+		    (char *)NULL);
 	    return TCL_ERROR;
 	}
 	Tcl_DStringGetResult(interp, &dstring);
@@ -2906,7 +2906,7 @@ TestgetplatformCmd(
 
     if (argc != 1) {
 	Tcl_AppendResult(interp, "wrong # arguments: should be \"", argv[0],
-		NULL);
+		(char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -4639,23 +4639,23 @@ TestseterrorcodeCmd(
     }
     switch (argc) {
     case 1:
-	Tcl_SetErrorCode(interp, "NONE", NULL);
+	Tcl_SetErrorCode(interp, "NONE", (char *)NULL);
 	break;
     case 2:
-	Tcl_SetErrorCode(interp, argv[1], NULL);
+	Tcl_SetErrorCode(interp, argv[1], (char *)NULL);
 	break;
     case 3:
-	Tcl_SetErrorCode(interp, argv[1], argv[2], NULL);
+	Tcl_SetErrorCode(interp, argv[1], argv[2], (char *)NULL);
 	break;
     case 4:
-	Tcl_SetErrorCode(interp, argv[1], argv[2], argv[3], NULL);
+	Tcl_SetErrorCode(interp, argv[1], argv[2], argv[3], (char *)NULL);
 	break;
     case 5:
-	Tcl_SetErrorCode(interp, argv[1], argv[2], argv[3], argv[4], NULL);
+	Tcl_SetErrorCode(interp, argv[1], argv[2], argv[3], argv[4], (char *)NULL);
 	break;
     case 6:
 	Tcl_SetErrorCode(interp, argv[1], argv[2], argv[3], argv[4],
-		argv[5], NULL);
+		argv[5], (char *)NULL);
     }
     return TCL_ERROR;
 }
@@ -4735,7 +4735,7 @@ TestfeventCmd(
 	} else {
 	    Tcl_AppendResult(interp,
 		    "called \"testfevent code\" before \"testfevent create\"",
-		    NULL);
+		    (char *)NULL);
 	    return TCL_ERROR;
 	}
     } else if (strcmp(argv[1], "create") == 0) {
@@ -7614,7 +7614,7 @@ TestconcatobjCmd(
     if (concatPtr == tmpPtr) {
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (a) concatObj is not a new obj ",
-		NULL);
+		(char *)NULL);
 	switch (tmpPtr->refCount) {
 	case 0:
 	    Tcl_AppendResult(interp, "(no new refCount)", NULL);
@@ -7641,7 +7641,7 @@ TestconcatobjCmd(
     if (concatPtr == tmpPtr) {
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (b) concatObj is not a new obj ",
-		NULL);
+		(char *)NULL);
 	switch (tmpPtr->refCount) {
 	case 0:
 	    Tcl_AppendResult(interp, "(refCount removed?)", NULL);
@@ -7770,7 +7770,7 @@ TestconcatobjCmd(
     if (concatPtr == tmpPtr) {
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (f) concatObj is not a new obj ",
-		NULL);
+		(char *)NULL);
 
 	(void) Tcl_ListObjLength(NULL, concatPtr, &len);
 	switch (tmpPtr->refCount) {
@@ -7801,7 +7801,7 @@ TestconcatobjCmd(
     if (concatPtr == tmpPtr) {
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (g) concatObj is not a new obj ",
-		NULL);
+		(char *)NULL);
 
 	(void) Tcl_ListObjLength(NULL, concatPtr, &len);
 	switch (tmpPtr->refCount) {
@@ -8165,7 +8165,7 @@ TestInterpResolverCmd(
     case 0: /*down*/
         if (!Tcl_RemoveInterpResolvers(interp, RESOLVER_KEY)) {
             Tcl_AppendResult(interp, "could not remove the resolver scheme",
-                    NULL);
+                    (char *)NULL);
             return TCL_ERROR;
         }
     }
diff --git a/generic/tclThreadTest.c b/generic/tclThreadTest.c
index 1302b4e..0040d75 100644
--- a/generic/tclThreadTest.c
+++ b/generic/tclThreadTest.c
@@ -917,7 +917,7 @@ ThreadSend(
 
     if (resultPtr->code != TCL_OK) {
 	if (resultPtr->errorCode) {
-	    Tcl_SetErrorCode(interp, resultPtr->errorCode, NULL);
+	    Tcl_SetErrorCode(interp, resultPtr->errorCode, (char *)NULL);
 	    ckfree(resultPtr->errorCode);
 	}
 	if (resultPtr->errorInfo) {
diff --git a/generic/tclTimer.c b/generic/tclTimer.c
index 3b8bcd6..2a71717 100644
--- a/generic/tclTimer.c
+++ b/generic/tclTimer.c
@@ -833,7 +833,7 @@ Tcl_AfterObjCmd(
                     "bad argument \"%s\": must be"
                     " cancel, idle, info, or an integer", arg));
             Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "INDEX", "argument",
-                    arg, NULL);
+                    arg, (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
@@ -972,7 +972,7 @@ Tcl_AfterObjCmd(
 
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                     "event \"%s\" doesn't exist", eventStr));
-            Tcl_SetErrorCode(interp, "TCL","LOOKUP","EVENT", eventStr, NULL);
+            Tcl_SetErrorCode(interp, "TCL","LOOKUP","EVENT", eventStr, (char *)NULL);
 	    return TCL_ERROR;
 	} else {
 	    Tcl_Obj *resultListPtr;
diff --git a/generic/tclTrace.c b/generic/tclTrace.c
index 8b5f2c3..11f3af4 100644
--- a/generic/tclTrace.c
+++ b/generic/tclTrace.c
@@ -372,7 +372,7 @@ Tcl_TraceObjCmd(
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "bad operations \"%s\": should be one or more of rwua",
 	    flagOps));
-    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "TRACE", "BADOPS", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "TRACE", "BADOPS", (char *)NULL);
     return TCL_ERROR;
 #endif
 }
@@ -443,7 +443,7 @@ TraceExecutionObjCmd(
 		    "bad operation list \"\": must be one or more of"
 		    " enter, leave, enterstep, or leavestep", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "TRACE", "NOOPS",
-		    NULL);
+		    (char *)NULL);
 	    return TCL_ERROR;
 	}
 	for (i = 0; i < listLen; i++) {
@@ -684,7 +684,7 @@ TraceCommandObjCmd(
 		    "bad operation list \"\": must be one or more of"
 		    " delete or rename", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "TRACE", "NOOPS",
-		    NULL);
+		    (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -883,7 +883,7 @@ TraceVariableObjCmd(
 		    "bad operation list \"\": must be one or more of"
 		    " array, read, unset, or write", -1));
 	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "TRACE", "NOOPS",
-		    NULL);
+		    (char *)NULL);
 	    return TCL_ERROR;
 	}
 	for (i = 0; i < listLen ; i++) {
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index dab5c3a..0d2df75 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -652,7 +652,7 @@ FindElement(
 			    "%s element in braces followed by \"%.*s\" "
 			    "instead of space", typeStr, (int) (p2-p), p));
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", typeCode, "JUNK",
-			    NULL);
+			    (char *)NULL);
 		}
 		return TCL_ERROR;
 	    }
@@ -704,7 +704,7 @@ FindElement(
 			    "%s element in quotes followed by \"%.*s\" "
 			    "instead of space", typeStr, (int) (p2-p), p));
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", typeCode, "JUNK",
-			    NULL);
+			    (char *)NULL);
 		}
 		return TCL_ERROR;
 	    }
@@ -737,7 +737,7 @@ FindElement(
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			"unmatched open brace in %s", typeStr));
 		Tcl_SetErrorCode(interp, "TCL", "VALUE", typeCode, "BRACE",
-			NULL);
+			(char *)NULL);
 	    }
 	    return TCL_ERROR;
 	} else if (inQuotes) {
@@ -745,7 +745,7 @@ FindElement(
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			"unmatched open quote in %s", typeStr));
 		Tcl_SetErrorCode(interp, "TCL", "VALUE", typeCode, "QUOTE",
-			NULL);
+			(char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -892,7 +892,7 @@ Tcl_SplitList(
 		Tcl_SetObjResult(interp, Tcl_NewStringObj(
 			"internal error in Tcl_SplitList", -1));
 		Tcl_SetErrorCode(interp, "TCL", "INTERNAL", "Tcl_SplitList",
-			NULL);
+			(char *)NULL);
 	    }
 	    return TCL_ERROR;
 	}
@@ -3698,7 +3698,7 @@ TclGetIntForIndex(
 	    bytes += 4;
 	}
 	TclCheckBadOctal(interp, bytes);
-	Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX", (char *)NULL);
     }
 
     return TCL_ERROR;
@@ -3822,7 +3822,7 @@ SetEndOffsetFromAny(
 	if (interp != NULL) {
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "bad index \"%s\": must be end?[+-]integer?", bytes));
-	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX", (char *)NULL);
 	}
 	return TCL_ERROR;
     }
@@ -3858,7 +3858,7 @@ SetEndOffsetFromAny(
 	if (interp != NULL) {
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		    "bad index \"%s\": must be end?[+-]integer?", bytes));
-	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX", (char *)NULL);
 	}
 	return TCL_ERROR;
     }
@@ -4701,7 +4701,7 @@ TclReToGlob(
   invalidGlob:
     if (interp != NULL) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(msg, -1));
-	Tcl_SetErrorCode(interp, "TCL", "RE2GLOB", code, NULL);
+	Tcl_SetErrorCode(interp, "TCL", "RE2GLOB", code, (char *)NULL);
     }
     Tcl_DStringFree(dsPtr);
     return TCL_ERROR;
diff --git a/generic/tclVar.c b/generic/tclVar.c
index 5cc1f3a..428cc0c 100644
--- a/generic/tclVar.c
+++ b/generic/tclVar.c
@@ -302,7 +302,7 @@ NotArrayError(
 
     Tcl_SetObjResult(interp,
 	    Tcl_ObjPrintf("\"%s\" isn't an array", nameStr));
-    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAY", nameStr, NULL);
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAY", nameStr, (char *)NULL);
     return TCL_ERROR;
 }
 
@@ -611,7 +611,7 @@ TclObjLookupVarEx(
 		if (flags & TCL_LEAVE_ERR_MSG) {
 		    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
 			    NOSUCHVAR, -1);
-		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "VARNAME", NULL);
+		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "VARNAME", (char *)NULL);
 		}
 		return NULL;
 	    }
@@ -647,7 +647,7 @@ TclObjLookupVarEx(
 			TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
 				NEEDARRAY, -1);
 			Tcl_SetErrorCode(interp, "TCL", "VALUE", "VARNAME",
-				NULL);
+				(char *)NULL);
 		    }
 		    return NULL;
 		}
@@ -713,7 +713,7 @@ TclObjLookupVarEx(
 	if ((errMsg != NULL) && (flags & TCL_LEAVE_ERR_MSG)) {
 	    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg, errMsg, -1);
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
-		    TclGetString(part1Ptr), NULL);
+		    TclGetString(part1Ptr), (char *)NULL);
 	}
 	if (newPart2) {
 	    Tcl_DecrRefCount(part2Ptr);
@@ -1086,7 +1086,7 @@ TclLookupArrayElement(
 		TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
 			NOSUCHVAR, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
-			arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
+			arrayNamePtr?TclGetString(arrayNamePtr):NULL, (char *)NULL);
 	    }
 	    return NULL;
 	}
@@ -1101,7 +1101,7 @@ TclLookupArrayElement(
 		TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
 			DANGLINGVAR, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
-			arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
+			arrayNamePtr?TclGetString(arrayNamePtr):NULL, (char *)NULL);
 	    }
 	    return NULL;
 	}
@@ -1121,7 +1121,7 @@ TclLookupArrayElement(
 	    TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg, NEEDARRAY,
 		    index);
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
-		    arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
+		    arrayNamePtr?TclGetString(arrayNamePtr):NULL, (char *)NULL);
 	}
 	return NULL;
     }
@@ -1142,7 +1142,7 @@ TclLookupArrayElement(
 		TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
 			NOSUCHELEMENT, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ELEMENT",
-			TclGetString(elNamePtr), NULL);
+			TclGetString(elNamePtr), (char *)NULL);
 	    }
 	}
     }
@@ -1481,7 +1481,7 @@ TclPtrGetVarIdx(
      */
 
   errorReturn:
-    Tcl_SetErrorCode(interp, "TCL", "READ", "VARNAME", NULL);
+    Tcl_SetErrorCode(interp, "TCL", "READ", "VARNAME", (char *)NULL);
     if (TclIsVarUndefined(varPtr)) {
 	TclCleanupVar(varPtr, arrayPtr);
     }
@@ -1884,11 +1884,11 @@ TclPtrSetVarIdx(
 	    if (TclIsVarArrayElement(varPtr)) {
 		TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set",
 			DANGLINGELEMENT, index);
-		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ELEMENT", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ELEMENT", (char *)NULL);
 	    } else {
 		TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set",
 			DANGLINGVAR, index);
-		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME", (char *)NULL);
 	    }
 	}
 	goto earlyError;
@@ -1901,7 +1901,7 @@ TclPtrSetVarIdx(
     if (TclIsVarArray(varPtr)) {
 	if (flags & TCL_LEAVE_ERR_MSG) {
 	    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set", ISARRAY,index);
-	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", (char *)NULL);
 	}
 	goto earlyError;
     }
@@ -2025,7 +2025,7 @@ TclPtrSetVarIdx(
 
   cleanup:
     if (resultPtr == NULL) {
-	Tcl_SetErrorCode(interp, "TCL", "WRITE", "VARNAME", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "WRITE", "VARNAME", (char *)NULL);
     }
     if (TclIsVarUndefined(varPtr)) {
 	TclCleanupVar(varPtr, arrayPtr);
@@ -2498,7 +2498,7 @@ TclPtrUnsetVarIdx(
 	if (flags & TCL_LEAVE_ERR_MSG) {
 	    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "unset",
 		    ((arrayPtr == NULL) ? NOSUCHVAR : NOSUCHELEMENT), index);
-	    Tcl_SetErrorCode(interp, "TCL", "UNSET", "VARNAME", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "UNSET", "VARNAME", (char *)NULL);
 	}
     }
 
@@ -3683,7 +3683,7 @@ ArraySetCmd(
 	CleanupVar(varPtr, arrayPtr);
 	TclObjVarErrMsg(interp, arrayNameObj, NULL, "set", NEEDARRAY, -1);
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
-		TclGetString(arrayNameObj), NULL);
+		TclGetString(arrayNameObj), (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -3750,7 +3750,7 @@ ArraySetCmd(
 	if (elemLen & 1) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "list must have an even number of elements", -1));
-	    Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "FORMAT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "ARGUMENT", "FORMAT", (char *)NULL);
 	    return TCL_ERROR;
 	}
 	if (elemLen == 0) {
@@ -3801,7 +3801,7 @@ ArraySetCmd(
 
 	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array set",
 		    NEEDARRAY, -1);
-	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
@@ -4185,7 +4185,7 @@ ObjMakeUpvar(
 		    "bad variable name \"%s\": can't create namespace "
 		    "variable that refers to procedure variable",
 		    TclGetString(myNamePtr)));
-	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "INVERTED", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "INVERTED", (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
@@ -4301,7 +4301,7 @@ TclPtrObjMakeUpvarIdx(
 			"bad variable name \"%s\": can't create a scalar "
 			"variable that looks like an array element", myName));
 		Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT",
-			NULL);
+			(char *)NULL);
 		return TCL_ERROR;
 	    }
 	}
@@ -4320,7 +4320,7 @@ TclPtrObjMakeUpvarIdx(
 	if (varPtr == NULL) {
 	    TclObjVarErrMsg(interp, myNamePtr, NULL, "create", errMsg, -1);
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
-		    TclGetString(myNamePtr), NULL);
+		    TclGetString(myNamePtr), (char *)NULL);
 	    return TCL_ERROR;
 	}
     }
@@ -4328,14 +4328,14 @@ TclPtrObjMakeUpvarIdx(
     if (varPtr == otherPtr) {
 	Tcl_SetObjResult((Tcl_Interp *) iPtr, Tcl_NewStringObj(
 		"can't upvar from variable to itself", -1));
-	Tcl_SetErrorCode(interp, "TCL", "UPVAR", "SELF", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "UPVAR", "SELF", (char *)NULL);
 	return TCL_ERROR;
     }
 
     if (TclIsVarTraced(varPtr)) {
 	Tcl_SetObjResult((Tcl_Interp *) iPtr, Tcl_ObjPrintf(
 		"variable \"%s\" has traces: can't use for upvar", myName));
-	Tcl_SetErrorCode(interp, "TCL", "UPVAR", "TRACED", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "UPVAR", "TRACED", (char *)NULL);
 	return TCL_ERROR;
     } else if (!TclIsVarUndefined(varPtr)) {
 	Var *linkPtr;
@@ -4350,7 +4350,7 @@ TclPtrObjMakeUpvarIdx(
 	if (!TclIsVarLink(varPtr)) {
 	    Tcl_SetObjResult((Tcl_Interp *) iPtr, Tcl_ObjPrintf(
 		    "variable \"%s\" already exists", myName));
-	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "EXISTS", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "EXISTS", (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -4700,7 +4700,7 @@ Tcl_VariableObjCmd(
 
 	    TclObjVarErrMsg(interp, varNamePtr, NULL, "define",
 		    ISARRAYELEMENT, -1);
-	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT", NULL);
+	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT", (char *)NULL);
 	    return TCL_ERROR;
 	}
 
@@ -4851,7 +4851,7 @@ Tcl_UpvarObjCmd(
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"bad level \"%s\"", TclGetString(levelObj)));
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "LEVEL",
-		TclGetString(levelObj), NULL);
+		TclGetString(levelObj), (char *)NULL);
 	return TCL_ERROR;
     }
 
@@ -4943,7 +4943,7 @@ SetArraySearchObj(
   syntax:
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "illegal search identifier \"%s\"", string));
-    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAYSEARCH", string, NULL);
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAYSEARCH", string, (char *)NULL);
     return TCL_ERROR;
 }
 
@@ -5037,7 +5037,7 @@ ParseSearchId(
     Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 	    "couldn't find search \"%s\"", string));
   badLookup:
-    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAYSEARCH", string, NULL);
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAYSEARCH", string, (char *)NULL);
     return NULL;
 }
 
@@ -5742,7 +5742,7 @@ ObjFindNamespaceVar(
     if ((varPtr == NULL) && (flags & TCL_LEAVE_ERR_MSG)) {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 		"unknown variable \"%s\"", name));
-	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARIABLE", name, NULL);
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARIABLE", name, (char *)NULL);
     }
     return (Tcl_Var) varPtr;
 }