Add (currently failing) test for correct virtual call resolution.

tests/mini/virtcall2.d

@@ -0,0 +1,78 @@
+enum {
+ COMMON,
+ INPUT,
+ OUTPUT,
+ CONDUIT,
+ OTHER
+}
+
+interface Common
+{ int common(); }
+
+interface Input : Common
+{ int input(); }
+
+interface Output : Common
+{ int output(); }
+
+interface Conduit : Input, Output
+{ abstract int conduit(); }
+
+class Abstract : Conduit
+{
+  abstract int conduit();
+  abstract int output();
+  abstract int input();
+  int common() { return COMMON; }
+}
+
+interface Other
+{ int other(); }
+
+class Impl : Abstract, Other
+{
+  int conduit() { return CONDUIT; }
+  int output() { return OUTPUT; }
+  int other() { return OTHER; }
+  int input() { return INPUT; }
+}
+
+void main()
+{
+  auto impl = new Impl;
+  
+  {
+    auto i = impl;
+    assert(i.common() == COMMON);
+    assert(i.input() == INPUT);
+    assert(i.output() == OUTPUT);
+    assert(i.conduit() == CONDUIT);
+    assert(i.other() == OTHER);
+  }
+  
+  {
+    Abstract i = impl;
+    assert(i.common() == COMMON);
+    assert(i.input() == INPUT);
+    assert(i.output() == OUTPUT);
+    assert(i.conduit() == CONDUIT);
+  }
+  
+  {
+    Conduit i = impl;
+    assert(i.common() == COMMON);
+    assert(i.input() == INPUT);
+    assert(i.output() == OUTPUT);
+    assert(i.conduit() == CONDUIT);
+  }
+
+  {
+    Output i = impl;
+    assert(i.output() == OUTPUT);
+  }
+  
+  {
+    Common i = impl;
+    assert(i.common() == COMMON);
+  }  
+}