From 391be07f42312180811c95f0a7def9c7c1597b01 Mon Sep 17 00:00:00 2001
From: Daniel Gale-Rosen <5487802+dangrous@users.noreply.github.com>
Date: Fri, 1 Nov 2024 14:38:18 -0400
Subject: [PATCH] Merge pull request #51879 from
 Expensify/arosiclair-fix-parent-report-loop

(cherry picked from commit e7267ea47bfc0ef56d1d590b44df19c230599c10)

(CP triggered by mountiny)
---
 src/libs/ReportUtils.ts | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/libs/ReportUtils.ts b/src/libs/ReportUtils.ts
index 7ad1b72dfebd..cfaa73650bcf 100644
--- a/src/libs/ReportUtils.ts
+++ b/src/libs/ReportUtils.ts
@@ -756,7 +756,7 @@ function getParentReport(report: OnyxEntry<Report>): OnyxEntry<Report> {
  * Returns the root parentReport if the given report is nested.
  * Uses recursion to iterate any depth of nested reports.
  */
-function getRootParentReport(report: OnyxEntry<Report>): OnyxEntry<Report> {
+function getRootParentReport(report: OnyxEntry<Report>, visitedReportIDs: Set<string> = new Set<string>()): OnyxEntry<Report> {
     if (!report) {
         return undefined;
     }
@@ -766,10 +766,18 @@ function getRootParentReport(report: OnyxEntry<Report>): OnyxEntry<Report> {
         return report;
     }
 
+    // Detect and prevent an infinite loop caused by a cycle in the ancestry. This should normally
+    // never happen
+    if (visitedReportIDs.has(report.reportID)) {
+        Log.alert('Report ancestry cycle detected.', {reportID: report.reportID, ancestry: Array.from(visitedReportIDs)});
+        return undefined;
+    }
+    visitedReportIDs.add(report.reportID);
+
     const parentReport = getReportOrDraftReport(report?.parentReportID);
 
     // Runs recursion to iterate a parent report
-    return getRootParentReport(!isEmptyObject(parentReport) ? parentReport : undefined);
+    return getRootParentReport(!isEmptyObject(parentReport) ? parentReport : undefined, visitedReportIDs);
 }
 
 /**