Merge pull request github#12707 from michaelnebel/csharp/dataflowstaticoperators

C#: Data flow tests for virtual and abstract operators.

Author: michaelnebel

csharp/ql/test/library-tests/dataflow/operators/Operator.cs

@@ -4,12 +4,22 @@ public class Operators
     static void Sink(object o) { }
     static T Source<T>(object source) => throw null;
 
-    public class C
+    public interface I<T> where T : I<T>
+    {
+        static virtual T operator *(T x, T y) => x;
+        static abstract T operator /(T x, T y);
+        static abstract T operator checked /(T x, T y);
+    }
+
+    public class C : I<C>
     {
         public static C operator +(C x, C y) => x;
 
         public static C operator checked -(C x, C y) => y;
         public static C operator -(C x, C y) => x;
+
+        public static C operator /(C x, C y) => y;
+        public static C operator checked /(C x, C y) => y;
     }
 
     public void M1()
@@ -35,4 +45,43 @@ public void M3()
         var z = checked(x - y);
         Sink(z); // $ hasValueFlow=6
     }
+
+    public void M4Aux<T>(T x, T y) where T : I<T>
+    {
+        var z = x * y;
+        Sink(z); // $ hasValueFlow=7
+    }
+
+    public void M4()
+    {
+        var x = Source<C>(7);
+        var y = Source<C>(8);
+        M4Aux(x, y);
+    }
+
+    public void M5Aux<T>(T x, T y) where T : I<T>
+    {
+        var z = x / y;
+        Sink(z); // $ hasValueFlow=10
+    }
+
+    public void M5()
+    {
+        var x = Source<C>(9);
+        var y = Source<C>(10);
+        M5Aux(x, y);
+    }
+
+    public void M6Aux<T>(T x, T y) where T : I<T>
+    {
+        var z = checked(x / y);
+        Sink(z); // $ hasValueFlow=12
+    }
+
+    public void M6()
+    {
+        var x = Source<C>(11);
+        var y = Source<C>(12);
+        M6Aux(x, y);
+    }
 }