Add generic types for strong mode

lib/src/protobuf/extension_field_set.dart

Index: lib/src/protobuf/extension_field_set.dart
diff --git a/lib/src/protobuf/extension_field_set.dart b/lib/src/protobuf/extension_field_set.dart
index e2bbd27ef3a419115895137aad6a47bed39ca8a8..87782624bb8cfd910d7171abba1a762a54f95c39 100644
--- a/lib/src/protobuf/extension_field_set.dart
+++ b/lib/src/protobuf/extension_field_set.dart
@@ -38,19 +38,19 @@ class _ExtensionFieldSet {
   ///
   /// If it doesn't exist, creates the list and saves the extension.
   /// Suitable for public API and decoders.
-  List _ensureRepeatedField(Extension fi) {
+  List/*<T>*/ _ensureRepeatedField/*<T>*/(Extension/*<T>*/ fi) {
     assert(fi.isRepeated);
     assert(fi.extendee == _parent._messageName);
 
     var list = _values[fi.tagNumber];
-    if (list != null) return list;
+    if (list != null) return list as List/*<T>*/;

[Leaf, 2016/04/01 17:09:56]

Is this going to have the right dynamic type (and hence work in DDC), or is it
going to be List<dynamic>?

[skybrian, 2016/04/01 18:01:40]

It's not statically checkable but the intent is that it always has the right
type. (The list should always be created by fi._createRepeatedField, below, and
the FieldInfo object should have been created with the right dynamic type.)

I'd be happier if I had a way to test this, though.

[skybrian, 2016/04/01 18:04:35]

On second thought, maybe this doesn't work? I'm returning a PbList<T> in place
of a List<T>. Will the "as" check succeed?

[Leaf, 2016/04/01 18:15:59]

If PbList<T> implements or extends List<T>, then yes.

 
     // Add info and create list.
     _validateInfo(fi);
-    list = _parent._message.createRepeatedField(fi.tagNumber, fi);
+    var newList = fi._createRepeatedField(_parent._message);
     _addInfoUnchecked(fi);
-    _setFieldUnchecked(fi, list);
-    return list;
+    _setFieldUnchecked(fi, newList);
+    return newList;
   }
 
   _getFieldOrNull(Extension extension) => _values[extension.tagNumber];