From 7d3cd7cba5a08304eec8f193ef070a89dd3bd31e Mon Sep 17 00:00:00 2001
From: Frank Tang <ftang@chromium.org>
Date: Mon, 11 Dec 2023 12:11:59 -0800
Subject: [PATCH] ICU-22584 Fix def of nullptr

ICU-22584 fix
---
 icu4c/source/common/rbbinode.cpp       | 12 +++++++-----
 icu4c/source/test/intltest/rbbitst.cpp |  3 +++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/icu4c/source/common/rbbinode.cpp b/icu4c/source/common/rbbinode.cpp
index a1f8b78e629..05b6efc642f 100644
--- a/icu4c/source/common/rbbinode.cpp
+++ b/icu4c/source/common/rbbinode.cpp
@@ -150,7 +150,7 @@ void RBBINode::NRDeleteNode(RBBINode *node) {
 
     RBBINode *stopNode = node->fParent;
     RBBINode *nextNode = node;
-    while (nextNode != stopNode) {
+    while (nextNode != stopNode && nextNode != nullptr) {
         RBBINode *currentNode = nextNode;
 
         if ((currentNode->fLeftChild == nullptr && currentNode->fRightChild == nullptr) ||
@@ -158,10 +158,12 @@ void RBBINode::NRDeleteNode(RBBINode *node) {
                 currentNode->fType == setRef) {      // own their children nodes.
             // CurrentNode is effectively a leaf node; it's safe to go ahead and delete it.
             nextNode = currentNode->fParent;
-            if (nextNode->fLeftChild == currentNode) {
-                nextNode->fLeftChild = nullptr;
-            } else if (nextNode->fRightChild == currentNode) {
-                nextNode->fRightChild = nullptr;
+            if (nextNode) {
+                if (nextNode->fLeftChild == currentNode) {
+                    nextNode->fLeftChild = nullptr;
+                } else if (nextNode->fRightChild == currentNode) {
+                    nextNode->fRightChild = nullptr;
+                }
             }
             delete currentNode;
         } else if (currentNode->fLeftChild) {
diff --git a/icu4c/source/test/intltest/rbbitst.cpp b/icu4c/source/test/intltest/rbbitst.cpp
index 16f1ea8081c..1145e332f51 100644
--- a/icu4c/source/test/intltest/rbbitst.cpp
+++ b/icu4c/source/test/intltest/rbbitst.cpp
@@ -5872,6 +5872,9 @@ void RBBITest::TestBug22584() {
     UErrorCode ec {U_ZERO_ERROR};
 
     RuleBasedBreakIterator bi(ruleStr, pe, ec);
+    ec = U_ZERO_ERROR;
+    ruleStr = u"a/b;c";
+    RuleBasedBreakIterator bi2(ruleStr, pe, ec);
 }
 
 void RBBITest::TestBug22581() {