From 394192ac8ae8ed1fbe341eb51afabd5b68fb871a Mon Sep 17 00:00:00 2001
From: Carlo Varni <75478407+CarloVarni@users.noreply.github.com>
Date: Fri, 17 Nov 2023 11:08:28 +0100
Subject: [PATCH] fix: Fitters: connect void default accessors (#2688)

Default void accessors that throws an error if the user forgets to set them. Right now this may cause crashes if the user forgets as @toyamaza has noticed in Athena
---
 Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp   | 1 +
 Core/include/Acts/TrackFitting/GsfOptions.hpp              | 3 +++
 Core/include/Acts/TrackFitting/KalmanFitter.hpp            | 1 +
 .../Acts/TrackFitting/detail/VoidFitterComponents.hpp      | 7 +++++++
 4 files changed, 12 insertions(+)

diff --git a/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp b/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
index d477e12f1fe..59b12e53f87 100644
--- a/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
+++ b/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
@@ -83,6 +83,7 @@ struct Gx2FitterExtensions {
     calibrator.template connect<&detail::voidFitterCalibrator<traj_t>>();
     updater.template connect<&detail::voidFitterUpdater<traj_t>>();
     outlierFinder.template connect<&detail::voidOutlierFinder<traj_t>>();
+    surfaceAccessor.connect<&detail::voidSurfaceAccessor>();
   }
 };
 
diff --git a/Core/include/Acts/TrackFitting/GsfOptions.hpp b/Core/include/Acts/TrackFitting/GsfOptions.hpp
index 0cf35fb11e6..488d07db12f 100644
--- a/Core/include/Acts/TrackFitting/GsfOptions.hpp
+++ b/Core/include/Acts/TrackFitting/GsfOptions.hpp
@@ -82,6 +82,9 @@ struct GsfExtensions {
     calibrator.template connect<&detail::voidFitterCalibrator<traj_t>>();
     updater.template connect<&detail::voidFitterUpdater<traj_t>>();
     outlierFinder.template connect<&detail::voidOutlierFinder<traj_t>>();
+    surfaceAccessor.connect<&detail::voidSurfaceAccessor>();
+    mixtureReducer
+        .template connect<&detail::voidComponentReducer<GsfComponent>>();
   }
 };
 
diff --git a/Core/include/Acts/TrackFitting/KalmanFitter.hpp b/Core/include/Acts/TrackFitting/KalmanFitter.hpp
index 377e290e951..014fd75e9bd 100644
--- a/Core/include/Acts/TrackFitting/KalmanFitter.hpp
+++ b/Core/include/Acts/TrackFitting/KalmanFitter.hpp
@@ -107,6 +107,7 @@ struct KalmanFitterExtensions {
     outlierFinder.template connect<&detail::voidOutlierFinder<traj_t>>();
     reverseFilteringLogic
         .template connect<&detail::voidReverseFilteringLogic<traj_t>>();
+    surfaceAccessor.connect<&detail::voidSurfaceAccessor>();
   }
 };
 
diff --git a/Core/include/Acts/TrackFitting/detail/VoidFitterComponents.hpp b/Core/include/Acts/TrackFitting/detail/VoidFitterComponents.hpp
index 7987f60eacd..ebc4ffabcef 100644
--- a/Core/include/Acts/TrackFitting/detail/VoidFitterComponents.hpp
+++ b/Core/include/Acts/TrackFitting/detail/VoidFitterComponents.hpp
@@ -63,4 +63,11 @@ bool voidReverseFilteringLogic(
 inline const Surface* voidSurfaceAccessor(const SourceLink& /*sourceLink*/) {
   throw std::runtime_error{"voidSurfaceAccessor should not ever execute"};
 }
+
+template <typename component_t>
+void voidComponentReducer(std::vector<component_t>& /*components*/,
+                          std::size_t /*n*/, const Surface& /*surface*/) {
+  throw std::runtime_error{"voidComponentReducer should not ever execute"};
+}
+
 }  // namespace Acts::detail