C#: Add more virtual dispatch tests

Author: hvitved

csharp/ql/test/library-tests/dispatch/CallGraph.expected

@@ -174,6 +174,14 @@
 | ViableCallable.cs:409:10:409:12 | Run | ViableCallable.cs:397:36:397:40 | M |
 | ViableCallable.cs:409:10:409:12 | Run | ViableCallable.cs:403:53:403:57 | M |
 | ViableCallable.cs:409:10:409:12 | Run | ViableCallable.cs:405:42:405:46 | M |
-| ViableCallable.cs:431:25:431:29 | M2 | ViableCallable.cs:442:17:442:23 | (...) => ... |
-| ViableCallable.cs:436:10:436:10 | M | ViableCallable.cs:430:23:430:24 | M1 |
-| ViableCallable.cs:436:10:436:10 | M | ViableCallable.cs:431:25:431:29 | M2 |
+| ViableCallable.cs:431:22:431:26 | M2 | ViableCallable.cs:456:14:456:29 | (...) => ... |
+| ViableCallable.cs:431:22:431:26 | M2 | ViableCallable.cs:462:14:462:29 | (...) => ... |
+| ViableCallable.cs:436:10:436:11 | M1 | ViableCallable.cs:430:23:430:24 | M1 |
+| ViableCallable.cs:436:10:436:11 | M1 | ViableCallable.cs:445:23:445:27 | M2 |
+| ViableCallable.cs:445:23:445:27 | M2 | ViableCallable.cs:442:17:442:23 | (...) => ... |
+| ViableCallable.cs:445:23:445:27 | M2 | ViableCallable.cs:456:14:456:29 | (...) => ... |
+| ViableCallable.cs:445:23:445:27 | M2 | ViableCallable.cs:462:14:462:29 | (...) => ... |
+| ViableCallable.cs:453:10:453:14 | M4 | ViableCallable.cs:431:22:431:26 | M2 |
+| ViableCallable.cs:453:10:453:14 | M4 | ViableCallable.cs:445:23:445:27 | M2 |
+| ViableCallable.cs:459:10:459:14 | M5 | ViableCallable.cs:431:22:431:26 | M2 |
+| ViableCallable.cs:459:10:459:14 | M5 | ViableCallable.cs:445:23:445:27 | M2 |

csharp/ql/test/library-tests/dispatch/GetADynamicTarget.expected

@@ -401,4 +401,8 @@
 | ViableCallable.cs:424:9:424:21 | call to method M | C15.A4.M<T1>() |
 | ViableCallable.cs:424:9:424:21 | call to method M | C15.A5.M<T1>() |
 | ViableCallable.cs:439:9:439:19 | call to method M1 | C16<String,Int32>.M1(string) |
-| ViableCallable.cs:442:9:442:24 | call to method M2 | C16<String,Int32>.M2<T>(Func<T>) |
+| ViableCallable.cs:442:9:442:24 | call to method M2 | C17.M2<T>(Func<T>) |
+| ViableCallable.cs:456:9:456:30 | call to method M2 | C16<T,Int32>.M2<T>(Func<T>) |
+| ViableCallable.cs:456:9:456:30 | call to method M2 | C17.M2<T>(Func<T>) |
+| ViableCallable.cs:462:9:462:30 | call to method M2 | C16<T,Int32>.M2<T>(Func<T>) |
+| ViableCallable.cs:462:9:462:30 | call to method M2 | C17.M2<T>(Func<T>) |

csharp/ql/test/library-tests/dispatch/ViableCallable.cs

@@ -428,17 +428,37 @@ void Run(I<int> i)
 abstract class C16<T1, T2>
 {
     public virtual T2 M1(T1 x) => throw null;
-    protected virtual T M2<T>(Func<T> x) => x();
+    public virtual T M2<T>(Func<T> x) => x();
 }
 
 class C17 : C16<string, int>
 {
-    void M(int i)
+    void M1(int i)
     {
         // Viable callables: C16<string, int>.M1()
         this.M1("");
 
         // Viable callables: C16<string, int>.M2<int>()
         this.M2(() => i);
     }
+
+    public override T M2<T>(Func<T> x) => x();
+
+    void M3<T>(T t, string s) where T : C17
+    {
+        // Viable callable: C17.M2()
+        t.M2(() => s);
+    }
+
+    void M4<T>(C16<T, int> c) where T : struct
+    {
+        // Viable callable: C16.M2() [also reports C17.M2(); false positive]
+        c.M2(() => default(T));
+    }
+
+    void M5<T>(C16<T, int> c) where T : class
+    {
+        // Viable callables: {C16,C17}.M1()
+        c.M2(() => default(T));
+    }
 }