MuonIDHltAlg - Cannot cache memory address of dd4hep detector elements.

dd4hep Detector elements are transient handles and thus their memory address should not be cached.

Muon/MuonID/src/component/MuonIDHltAlg.cpp

@@ -64,8 +64,8 @@ namespace {
   struct MiniID {
     LHCb::Event::flags_v<scalar_t, StatusMasks> flags;
     float                                       chi2Corr = -10000.0f;
-    float                                       LLMu     = log( 0.00001f );
-    float                                       LLBg     = log( 1.0f );
+    float                                       LLMu     = std::log( 0.00001f );
+    float                                       LLBg     = std::log( 1.0f );
     float                                       CatBoost = -999.f;
     std::array<LHCb::LHCbID, nMuonStations>     tiles{};
   };
@@ -76,21 +76,32 @@ namespace details {
 
   class Cache {
   public:
-    const DeMuonDetector*  m_det           = nullptr;
-    size_t                 m_stationsCount = 0;
-    size_t                 m_regionsCount  = 0;
-    MuonTrackExtrapolation m_regionInner, m_regionOuter;
-    SigmaPadCache          m_sigmapadX, m_sigmapadY;
-    ScatterCache           m_scattercache;
-    std::array<float, 4>   m_stationZ{{}};
+#ifdef USE_DD4HEP
+    DeMuonDetector m_det;
+#else
+    const DeMuonDetector* m_det = nullptr;
+#endif
+    size_t                           m_stationsCount = 0;
+    size_t                           m_regionsCount  = 0;
+    MuonTrackExtrapolation           m_regionInner, m_regionOuter;
+    SigmaPadCache                    m_sigmapadX, m_sigmapadY;
+    ScatterCache                     m_scattercache;
+    std::array<float, nMuonStations> m_stationZ{{}};
 
   public:
-    Cache() = default;
     Cache( DeMuonDetector const& det )
-        : m_det{&det}, m_stationsCount( det.stations() ), m_regionsCount{det.regions() / m_stationsCount} {
+        : m_stationsCount( det.stations() ), m_regionsCount{det.regions() / m_stationsCount} {
+
+      // DetElems with dd4hep are transient handles with no persistent lifetime so you
+      // cannot take the memory address ofthem and cache this, as with DetDesc.
+      // Instead just copy the handle.
+#ifdef USE_DD4HEP
+      m_det = det;
+#else
+      m_det = &det;
+#endif
 
       // Update the cached DeMuon geometry (should be done by the detector element..)
-      // det.fillGeoArray();
       for ( int s = 0; s != det.stations(); ++s ) {
         m_regionInner[s] = std::make_pair( det.getInnerX( s ), det.getInnerY( s ) );
         m_regionOuter[s] = std::make_pair( det.getOuterX( s ), det.getOuterY( s ) );
@@ -461,7 +472,13 @@ private: // methods
       for ( const auto& hit : hitContainer.station( station ).hits() ) {
         if ( predicate( hit ) ) {
           occupancies[station]++;
-          if ( !hit.uncrossed() || cond.m_det->mapInRegion( station, hit.region() ) == 1 ) {
+          if ( !hit.uncrossed() ||
+#ifdef USE_DD4HEP
+               cond.m_det.mapInRegion( station, hit.region() ) == 1
+#else
+               cond.m_det->mapInRegion( station, hit.region() ) == 1
+#endif
+          ) {
             occupancies_crossed[station]++;
           }
         }