Support runtime check of function types.

tests/language/function_subtype0_test.dart

+// 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.
+// Dart test program for constructors and initializers.
+
+// Check function subtyping.
+
+import 'package:expect/expect.dart';
+
+typedef t__();
+typedef void t_void_();
+typedef void t_void_2();
+typedef int t_int_();
+typedef int t_int_2();
+typedef Object t_Object_();
+typedef double t_double_();
+typedef void t_void__int(int i);
+typedef int t_int__int(int i);
+typedef int t_int__int2(int i);
+typedef int t_int__Object(Object o);
+typedef Object t_Object__int(int i);
+typedef int t_int__double(double d);
+typedef int t_int__int_int(int i1, int i2);
+typedef void t_inline_void_(void f());
+typedef void t_inline_void__int(void f(int i));
+
+void _() => null;
+void void_() {}
+void void_2() {}
+int int_() => 0;
+int int_2() => 0;
+Object Object_() => null;
+double double_() => 0.0;
+void void__int(int i) {}
+int int__int(int i) => 0;
+int int__int2(int i) => 0;
+int int__Object(Object o) => 0;
+Object Object__int(int i) => null;
+int int__double(double d) => 0;
+int int__int_int(int i1, int i2) => 0;
+void inline_void_(void f()) {}
+void inline_void__int(void f(int i)) {}
+
+main() {
+  // () -> int <: Function
+  Expect.isTrue(int_ is Function);
+  // () -> dynamic <: () -> dynamic
+  Expect.isTrue(_ is t__);
+  // () -> dynamic <: () -> void
+  Expect.isTrue(_ is t_void_);
+  // () -> void <: () -> dynamic
+  Expect.isTrue(void_ is t__);
+  // () -> int <: () -> void
+  Expect.isTrue(int_ is t_void_);
+  // () -> void <: () -> int
+  Expect.isFalse(void_ is t_int_);
+  // () -> void <: () -> void
+  Expect.isTrue(void_ is t_void_2);
+  // () -> int <: () -> int
+  Expect.isTrue(int_ is t_int_2);
+  // () -> int <: () -> Object
+  Expect.isTrue(int_ is t_Object_);
+  // () -> int <: () -> double
+  Expect.isFalse(int_ is t_double_);
+  // () -> int <: (int) -> void
+  Expect.isFalse(int_ is t_void__int);
+  // () -> void <: (int) -> int
+  Expect.isFalse(void_ is t_int__int);
+  // () -> void <: (int) -> void
+  Expect.isFalse(void_ is t_void__int);
+  // (int) -> int <: (int) -> int
+  Expect.isTrue(int__int is t_int__int2);
+  // (Object) -> int <: (int) -> Object
+  Expect.isTrue(int__Object is t_Object__int);
+  // (int) -> int <: (double) -> int
+  Expect.isFalse(int__int is t_int__double);
+  // () -> int <: (int) -> int
+  Expect.isFalse(int_ is t_int__int);
+  // (int) -> int <: (int,int) -> int
+  Expect.isFalse(int__int is t_int__int_int);
+  // (int,int) -> int <: (int) -> int
+  Expect.isFalse(int__int_int is t_int__int);
+  // (()->void) -> void <: ((int)->void) -> void
+  Expect.isFalse(inline_void_ is t_inline_void__int);
+  // ((int)->void) -> void <: (()->void) -> void
+  Expect.isFalse(inline_void__int is t_inline_void_);
+}