dart2js: Capture typedef arguments once

tests/compiler/dart2js_extra/28749_test.dart

Index: tests/compiler/dart2js_extra/28749_test.dart
diff --git a/tests/compiler/dart2js_extra/28749_test.dart b/tests/compiler/dart2js_extra/28749_test.dart
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+++ b/tests/compiler/dart2js_extra/28749_test.dart
@@ -0,0 +1,57 @@
+// 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.
+
+// Regression test for http://dartbug.com/28749.
+//
+// This would crash at compile time because inner typedefs remain after calling
+// [type.unalias].  Expanding the typedef causes the inputs to be used multiple
+// types, breaking the invariant of HTypeInfoExpression that the type variable
+// occurrences correspond to inputs.
+
+import 'package:expect/expect.dart';
+
+typedef void F<T>(T value);
+typedef F<U> Converter<U>(F<U> function);
+typedef Converter<V> ConvertFactory<V>(int input);
+
+class B<W> {
+  final field = new Wrap<ConvertFactory<W>>();
+  @NoInline()
+  B();
+}
+
+class Wrap<X> {
+  @NoInline()
+  Wrap();
+}
+
+foo<Y>(int x) {
+  if (x == 0)
+    return new Wrap<ConvertFactory<Y>>().runtimeType;
+  else
+    return new B<Y>().field.runtimeType;
+}
+
+void main() {
+  var name = '${Wrap}';
+  if (name.length < 4) return; // minified.
+
+  Expect.equals(
+    'Wrap<(int) => ((int) => void) => (int) => void>',
+    '${new B<int>().field.runtimeType}',
+  );
+  Expect.equals(
+    'Wrap<(int) => ((bool) => void) => (bool) => void>',
+    '${new B<bool>().field.runtimeType}',
+  );
+
+  Expect.equals(
+    'Wrap<(int) => ((dynamic) => void) => (dynamic) => void>',
+    '${foo<int>(0)}',
+  );
+  Expect.equals(
+    'Wrap<(int) => ((dynamic) => void) => (dynamic) => void>',
+    '${foo<String>(1)}',
+  );
+}