Can't resolve Dart App Engine dependency - google-app-engine

Question

I am trying to build a Dart application for Google App Engine but Dart can't resolve any appengine dependency except for the 0.0.1 version. Here is my pubspec.yaml:
name: MyApp
version: 0.0.1
dependencies:
angular2: 2.0.0-alpha.44
browser: ^0.10.0
appengine: '>=0.3.0 < 0.4.0'
transformers:
- angular2:
entry_points: web/main.dart
This is the error I get:
Package appengine has no versions that match >=0.3.0 <0.4.0 derived from:
- MyApp depends on version >=0.3.0 <0.4.0
I have tried every appengine version from https://pub.dartlang.org/packages/appengine/versions but the only one that works is ^0.0.1
Downloading appengine 0.0.1...
Got dependencies!
I would really like to use something newer than 0.0.1. Is something broken or am I missing something?
*Update:
I ran in verbose mode as per Günter Zöchbauer's suggestion and this is the output:
ERR : Package appengine has no versions that match >=0.0.2 <0.4.0 derived from:
| - MyApp depends on version >=0.0.2 <0.4.0
FINE: Exception type: NoVersionException
FINE: package:pub/src/entrypoint.dart 154 Entrypoint.acquireDependencies.<async>
| ===== asynchronous gap ===========================
| dart:async _Completer.completeError
| package:pub/src/entrypoint.dart 199 Entrypoint.acquireDependencies.<async>
| ===== asynchronous gap ===========================
| dart:async _Future.then
| package:pub/src/entrypoint.dart 152 Entrypoint.acquireDependencies.<async>
| ===== asynchronous gap ===========================
| dart:async Future.Future.microtask
| package:pub/src/entrypoint.dart Entrypoint.acquireDependencies
| package:pub/src/command/get.dart 30 GetCommand.run
| package:args/command_runner.dart 178 CommandRunner.runCommand.<fn>
| dart:async Future.Future.sync
| package:args/command_runner.dart 131 CommandRunner.runCommand
| package:pub/src/command_runner.dart 130 PubCommandRunner.runCommand.<async>.<fn>
| dart:async Future.Future.sync
| package:pub/src/utils.dart 103 captureErrors.<fn>
| package:stack_trace Chain.capture
| package:pub/src/utils.dart 117 captureErrors
| package:pub/src/command_runner.dart 130 PubCommandRunner.runCommand.<async>
I expanded the version to include anything between 0.0.2 and 0.4.0 and it fails. It is definitely throwing a no version found error even though I can manually download the versions from the web.

Answer 1

This is a known issue with pub. If it can't resolve a matching set of dependencies it sometimes prints misleading messages.
pub upgrade --verbose
should reveal more information that allows to investigate what dependencies pub is unable to find compatible versions of.
The conflict is the protobuf package.
appengine 0.3.2 depends on protobuf 0.5.0
angular2 2.0.0-alpha.44 depends on protobuf 0.4.2
but angular2 2.0.0-alpha.45 also depends on protobuf 0.5.0
If you change your angular dependency to
angular2: ^2.0.0-alpha.44
or
angular2: 2.0.0-alpha.45
or
angular2: ^2.0.0-alpha
pub can resolve all dependencies just fine.