From 4add06b3285389a167d52b0b6558320e8ea4e75c Mon Sep 17 00:00:00 2001
From: Christopher Jones <chrisdjones15@gmail.com>
Date: Mon, 10 Nov 2025 10:47:03 -0600
Subject: [PATCH] Need to add TracksHost::Implementation to classes_def.xml

This avoids a segmentation fault in new version of ROOT.
---
 DataFormats/TrackSoA/src/classes_def.xml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/DataFormats/TrackSoA/src/classes_def.xml b/DataFormats/TrackSoA/src/classes_def.xml
index 6341f72e512f6..0756f11d83910 100644
--- a/DataFormats/TrackSoA/src/classes_def.xml
+++ b/DataFormats/TrackSoA/src/classes_def.xml
@@ -4,6 +4,9 @@
   <class name="reco::TrackHitsLayout<128, false>"/>
 
   <class name="reco::TracksHost" rntupleStreamerMode="true"/>
+  <!-- In principle this should not be necessary, but it looks like it is triggering a bug (?) in ROOT/cling. -->
+  <!-- For more details see the discussion in #49333 and #49360. -->
+  <class name="reco::TracksHost::Implementation"/>
   <class name="edm::Wrapper<reco::TracksHost>" splitLevel="0"/>
 
   <!-- Recursive templates (with no data) ensuring we have one CollectionLeaf<index, type> for each layout in the collection -->