Bug [983f933f11] UBSan warnings with null pointer in TclGetProcessGlobal/Tcl_ExternalToUtfDString.

Author: apnadkarni

generic/tclEncoding.c

@@ -1206,6 +1206,7 @@ Tcl_ExternalToUtfDStringEx(
 
     if (src == NULL) {
 	srcLen = 0;
+	src = "";	/* Avoid ABSAN warnings about ops on NULL pointers */
     } else if (srcLen < 0) {
 	srcLen = encodingPtr->lengthProc(src);
     }
@@ -1342,6 +1343,7 @@ Tcl_ExternalToUtf(
 
     if (src == NULL) {
 	srcLen = 0;
+	src = "";	/* Avoid ABSAN warnings about ops on NULL pointers */
     } else if (srcLen < 0) {
 	Encoding *encodingPtr = (Encoding *)encoding;
 	if (encodingPtr == NULL) {
@@ -1462,6 +1464,7 @@ Tcl_ExternalToUtfEx(
 
     if (src == NULL) {
 	srcLen = 0;
+	src = "";	/* Avoid ABSAN warnings about ops on NULL pointers */
     } else if (srcLen < 0) {
 	srcLen = encodingPtr->lengthProc(src);
     }
@@ -1773,6 +1776,7 @@ Tcl_UtfToExternalDStringEx(
 
     if (src == NULL) {
 	srcLen = 0;
+	src = "";	/* Avoid ABSAN warnings about ops on NULL pointers */
     } else if (srcLen < 0) {
 	srcLen = strlen(src);
     }
@@ -1911,6 +1915,7 @@ Tcl_UtfToExternal(
 
     if (src == NULL) {
 	srcLen = 0;
+	src = "";	/* Avoid ABSAN warnings about ops on NULL pointers */
     } else if (srcLen < 0) {
 	srcLen = strlen(src);
     }
@@ -2033,6 +2038,7 @@ Tcl_UtfToExternalEx(
 
     if (src == NULL) {
 	srcLen = 0;
+	src = "";	/* Avoid ABSAN warnings about ops on NULL pointers */
     } else if (srcLen < 0) {
 	srcLen = strlen(src); /* strlen works for TUTF-8 */
     }