C#: WIP: Fix calls with no target in DB quality query

Author: tamasvajk

csharp/ql/src/Telemetry/DatabaseQuality.qll

@@ -77,6 +77,12 @@ module CallTargetStats implements StatsSig {
     )
   }
 
+  private predicate isEventFieldAccess(EventCall c) {
+    exists(Event e | c.getEvent() = e |
+      forall(Accessor a | e.getAnAccessor() = a | a.isCompilerGenerated())
+    )
+  }
+
   additional predicate isNotOkCall(Call c) {
     not exists(c.getTarget()) and
     not c instanceof DelegateCall and
@@ -85,7 +91,8 @@ module CallTargetStats implements StatsSig {
     not isNoSetterPropertyInitialization(c) and
     not isAnonymousObjectMemberDeclaration(c) and
     not isInitializedWithCollectionInitializer(c) and
-    not c.getParent+() instanceof NameOfExpr
+    not c.getParent+() instanceof NameOfExpr and
+    not isEventFieldAccess(c)
   }
 
   int getNumberOfNotOk() { result = count(Call c | isNotOkCall(c)) }

csharp/ql/test/query-tests/Telemetry/DatabaseQuality/IsNotOkayCall.expected

@@ -0,0 +1,4 @@
+| Quality.cs:25:19:25:26 | access to indexer | Call without target $@. | Quality.cs:25:19:25:26 | access to indexer | access to indexer |
+| Quality.cs:28:21:28:27 | access to indexer | Call without target $@. | Quality.cs:28:21:28:27 | access to indexer | access to indexer |
+| Quality.cs:31:9:31:21 | access to indexer | Call without target $@. | Quality.cs:31:9:31:21 | access to indexer | access to indexer |
+| Quality.cs:46:20:46:26 | object creation of type T | Call without target $@. | Quality.cs:46:20:46:26 | object creation of type T | object creation of type T |

csharp/ql/test/query-tests/Telemetry/DatabaseQuality/NoTarget.expected

@@ -4,4 +4,10 @@
 | Quality.cs:15:24:15:34 | access to property MyProperty3 | Call without target $@. | Quality.cs:15:24:15:34 | access to property MyProperty3 | access to property MyProperty3 |
 | Quality.cs:15:24:15:46 | access to property MyProperty2 | Call without target $@. | Quality.cs:15:24:15:46 | access to property MyProperty2 | access to property MyProperty2 |
 | Quality.cs:19:13:19:23 | access to property MyProperty4 | Call without target $@. | Quality.cs:19:13:19:23 | access to property MyProperty4 | access to property MyProperty4 |
-| Quality.cs:24:16:24:26 | access to property MyProperty2 | Call without target $@. | Quality.cs:24:16:24:26 | access to property MyProperty2 | access to property MyProperty2 |
+| Quality.cs:22:9:22:14 | access to event Event1 | Call without target $@. | Quality.cs:22:9:22:14 | access to event Event1 | access to event Event1 |
+| Quality.cs:22:9:22:30 | delegate call | Call without target $@. | Quality.cs:22:9:22:30 | delegate call | delegate call |
+| Quality.cs:25:19:25:26 | access to indexer | Call without target $@. | Quality.cs:25:19:25:26 | access to indexer | access to indexer |
+| Quality.cs:28:21:28:27 | access to indexer | Call without target $@. | Quality.cs:28:21:28:27 | access to indexer | access to indexer |
+| Quality.cs:31:9:31:21 | access to indexer | Call without target $@. | Quality.cs:31:9:31:21 | access to indexer | access to indexer |
+| Quality.cs:35:16:35:26 | access to property MyProperty2 | Call without target $@. | Quality.cs:35:16:35:26 | access to property MyProperty2 | access to property MyProperty2 |
+| Quality.cs:46:20:46:26 | object creation of type T | Call without target $@. | Quality.cs:46:20:46:26 | object creation of type T | object creation of type T |

csharp/ql/test/query-tests/Telemetry/DatabaseQuality/Quality.cs

@@ -18,11 +18,32 @@ public Test()
         {
             MyProperty4 = { 1, 2, 3 }
         };
+
+        Event1.Invoke(this, 5);
+
+        var str = "abcd";
+        var sub = str[..3];
+
+        Span<int> sp = null;
+        var slice = sp[..3];
+
+        Span<byte> guidBytes = stackalloc byte[16];
+        guidBytes[08] = 1;
     }
 
     public int MyProperty1 { get; }
     public int MyProperty2 { get; } = 42;
     public Test MyProperty3 { get; set; }
     public List<int> MyProperty4 { get; }
     static int MyProperty5 { get; }
+
+    public event EventHandler<int> Event1;
+
+    class Gen<T> where T : new()
+    {
+        public static T Factory()
+        {
+            return new T();
+        }
+    }
 }