C++: Add failing test.

cpp/ql/test/library-tests/dataflow/dataflow-tests/test.cpp

@@ -1115,4 +1115,20 @@ void indirect_sink_const_ref(const T&);
 
 void test_temp_with_conversion_from_materialization() {
   indirect_sink_const_ref(source()); // $ ir MISSING: ast
+}
+
+void reads_input(int x) {
+  sink(x); // $ MISSING: ast,ir
+}
+
+void not_does_read_input(int x);
+
+void (*dispatch_table[])(int) = {
+  reads_input,
+  not_does_read_input
+};
+
+void test_dispatch_table(int i) {
+  int x = source();
+  dispatch_table[i](x);
 }