Test some more complex cases of covariant generic parameters.

pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_complex.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*@testedFeatures=checks*/
+library test;
+
+class C<T> {
+  // List<T> is covariant in T so it needs checking
+  void f1(List<T> /*@checkFormal=semiSafe*/ x) {}
+
+  // () -> T is covariant in T so it needs checking
+  void f2(T /*@checkFormal=semiSafe*/ callback()) {}
+
+  // (T) -> T is partially covariant in T so it needs checking
+  void f3(T /*@checkFormal=semiSafe*/ callback(T x)) {}
+
+  // (T) -> void is contravariant in T so it doesn't need checking
+  void f4(void callback(T x)) {}
+}
+
+void g1(C<num> c, List<num> l) {
+  c.f1 /*@checkCall=interface(semiTyped:0)*/ (l);
+}
+
+void g2(C<num> c, num callback()) {
+  c.f2 /*@checkCall=interface(semiTyped:0)*/ (callback);
+}
+
+void g3(C<num> c, num callback(num x)) {
+  c.f3 /*@checkCall=interface(semiTyped:0)*/ (callback);
+}
+
+void g4(C<num> c, void callback(num x)) {
+  c.f4(callback);
+}
+
+main() {}