BeamSpotMonitor: Suppress unused functions warnings

Tr/TrackMonitors/CMakeLists.txt

@@ -15,13 +15,13 @@ Tr/TrackMonitors
 
 gaudi_add_module(TrackMonitors
     SOURCES
-	    src/FTTrackMonitor.cpp
+        src/FTTrackMonitor.cpp
         src/FTMatCalibrationMonitor.cpp
-	src/FTHitEfficiencyMonitor.cpp
+        src/FTHitEfficiencyMonitor.cpp
         src/PrSciFiHitsMonitor.cpp
         src/Map.cpp
         src/MonitorDetectorCorrelations.cpp
-	src/MonitorECALEnergyHitsCorrelations.cpp
+        src/MonitorECALEnergyHitsCorrelations.cpp
         src/TrackCaloMatchMonitor.cpp
         src/TrackDiMuonMonitor.cpp
         src/TrackFitMatchMonitor.cpp
@@ -37,7 +37,7 @@ gaudi_add_module(TrackMonitors
         src/TrackVPOverlapMonitor.cpp
         src/UTTrackMonitor.cpp
         src/VPTrackMonitor.cpp
-	src/VPHitEfficiencyMonitor.cpp
+        src/VPHitEfficiencyMonitor.cpp
         src/VertexCompare.cpp
         src/BeamSpotMonitor.cpp
     LINK
@@ -70,9 +70,15 @@ gaudi_add_module(TrackMonitors
         Rec::TrackFitEvent
         Rec::TrackInterfacesLib
         Rec::TrackKernel
-	Rec::PrKernel
+        Rec::PrKernel
         ROOT::Hist
         ROOT::MathCore
-)
+    )
+
+# Beam spot monitor uses meta_enum to generate a private enum.
+# This causes unused function warnings with clang as some of
+# the generated methods are indeed not required and unused.
+# Just disable this for this one compilation
+set_property(SOURCE src/BeamSpotMonitor.cpp APPEND PROPERTY COMPILE_OPTIONS "-Wno-unused-function")
 
 gaudi_install(PYTHON)