Support type promotion in dart2js.

tests/language/type_promotion_functions_test.dart

Index: tests/language/type_promotion_functions_test.dart
diff --git a/tests/language/type_promotion_functions_test.dart b/tests/language/type_promotion_functions_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..e6cc0c46a249a6cf0be1d1d45aab7ecfc51076c7
--- /dev/null
+++ b/tests/language/type_promotion_functions_test.dart
@@ -0,0 +1,113 @@
+// Copyright (c) 2013, 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.
+
+// Test type promotion of functions.
+
+class A {}
+class B extends A {}
+class C {}
+
+// We have the following more specific (<<) relations between these typedefs:
+//
+//  FuncDynToDyn << FuncAtoDyn
+//  FuncDynToDyn << FuncDynToA << FuncDynToVoid
+
+typedef FuncAtoDyn(A a);
+typedef FuncDynToDyn(x);
+typedef void FuncDynToVoid(x);
+typedef A FuncDynToA(x);
+
+func(x) => x;
+
+A a;
+B b;
+C c;
+
+main() {
+  testFuncAtoDyn();
+  testFuncDynToDyn();
+  testFuncDynToVoid();
+  testFuncDynToA();
+}
+
+testFuncAtoDyn() {
+  FuncAtoDyn funcAtoDyn = func;
+  a = funcAtoDyn(new A());
+  b = funcAtoDyn(new B());
+  c = funcAtoDyn(new C()); /// 01: static type warning
+
+  if (funcAtoDyn is FuncDynToDyn) { // Promotion: FuncDynToDyn << FuncAtoDyn.
+    a = funcAtoDyn(new A());
+    b = funcAtoDyn(new B());
+    c = funcAtoDyn(new C());
+  }
+}
+
+testFuncDynToDyn() {
+  FuncDynToDyn funcDynToDyn = func;
+  a = funcDynToDyn(new A());
+  b = funcDynToDyn(new B());
+  c = funcDynToDyn(new C());
+
+  if (funcDynToDyn is FuncAtoDyn) {
+    // No promotion: FuncAtoDyn !<< FuncDynToDyn.
+    a = funcDynToDyn(new A());
+    b = funcDynToDyn(new B());
+    c = funcDynToDyn(new C());
+  }
+
+  if (funcDynToDyn is FuncDynToVoid) {
+    // No promotion: FuncDynToVoid !<< FuncDynToDyn.
+    a = funcDynToDyn(new A());
+    b = funcDynToDyn(new B());
+    c = funcDynToDyn(new C());
+  }
+
+  if (funcDynToDyn is FuncDynToA) {
+    // No promotion: FuncDynToA !<< FuncDynToDyn.
+    a = funcDynToDyn(new A());
+    b = funcDynToDyn(new B());
+    c = funcDynToDyn(new C());
+  }
+}
+
+testFuncDynToVoid() {
+  FuncDynToVoid funcDynToVoid = func;
+  a = funcDynToVoid(new A()); /// 02: static type warning
+  b = funcDynToVoid(new B()); /// 03: static type warning
+  c = funcDynToVoid(new C()); /// 04: static type warning
+
+  if (funcDynToVoid is FuncDynToDyn) {
+    // Promotion: FuncDynToDyn << FuncDynToVoid.
+    a = funcDynToVoid(new A());
+    b = funcDynToVoid(new B());
+    c = funcDynToVoid(new C());
+  }
+
+  if (funcDynToVoid is FuncDynToA) { // Promotion: FuncDynToA << FuncDynToVoid.
+    a = funcDynToVoid(new A());
+    b = funcDynToVoid(new B());
+    c = funcDynToVoid(new C()); /// 05: static type warning
+  }
+}
+
+testFuncDynToA() {
+  FuncDynToA funcDynToA = func;
+  a = funcDynToA(new A());
+  b = funcDynToA(new B());
+  c = funcDynToA(new C()); /// 06: static type warning
+
+  if (funcDynToA is FuncDynToDyn) { // Promotion: FuncDynToDyn << FuncDynToA.
+    a = funcDynToA(new A());
+    b = funcDynToA(new B());
+    c = funcDynToA(new C());
+  }
+
+  if (funcDynToA is FuncDynToVoid) {
+    // No promotion: FuncDynToVoid !<< FuncDynToA.
+    a = funcDynToA(new A());
+    b = funcDynToA(new B());
+    c = funcDynToA(new C()); /// 07: static type warning
+  }
+}