Handle for-in loops

test/checker/inferred_type_test.dart

 // Copyright (c) 2015, 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.
 
 /// Tests for type inference.
 library dev_compiler.test.inferred_type_test;
 
 import 'package:unittest/unittest.dart';
 
 import 'package:dev_compiler/src/testing.dart';
@@ skipping 569 matching lines @@
 
   test('infer types on loop indices', () {
     // foreach loop
     testChecker({
       '/main.dart': '''
       class Foo {
         int bar = 42;
       }
 
       test() {
-        var l = List<Foo>();
+        var list = <Foo>[];
         for (var x in list) {
-          String y = /*info:DynamicCast should be severe:StaticTypeError*/x;
+          String y = /*severe:StaticTypeError*/x;
+        }
+
+        for (dynamic x in list) {
+          String y = /*info:DynamicCast*/x;
+        }
+
+        for (String x in /*severe:StaticTypeError*/list) {
+          String y = x;
+        }
+
+        var z;
+        for(z in list) {
+          String y = /*info:DynamicCast*/z;
+        }
+
+        Iterable iter = list;
+        for (Foo x in /*warning:DownCastComposite*/iter) {
+          var y = x;
+        }
+
+        dynamic iter2 = list;
+        for (Foo x in /*warning:DownCastComposite*/iter2) {
+          var y = x;
+        }
+
+        var map = <String, Foo>{};
+        for (var x in /*severe:StaticTypeError*/map) {

[Siggi Cherem (dart-lang), 2015/03/30 23:42:12]

is this an error because the type is not iterable? could you add a little
comment to clarify?

[vsm, 2015/03/31 00:24:47]

Yes, a cast is needed and will fail here.  Note, I added another test case -
that one is unfortunately off.  Somehow, we're not computing that map.keys is an
Iterable<String> - at least not computing that soon enough.

+          String y = /*info:DynamicCast*/x;
         }
       }
       '''
     });
 
     // for loop, with inference
     testChecker({
       '/main.dart': '''
       test() {
         for (var i = 0; i < 10; i++) {
@@ skipping 570 matching lines @@
           static final T foo = m1(m2(m3('', '')));
           static T m1(String m) { return null; }
           static String m2(e) { return ''; }
         }
 
 
     '''
     }, inferFromOverrides: true, inferTransitively: true);
   });
 }