As of Dart 2, pub no longer supports pub build, pub serve, or transformers. They’re replaced by the build system, which includes the build_runner tool.

For information about building and serving apps in Dart 2, see the following:

• build_runner documentation
• Build system documents, including getting started with build_runner

For help in switching from Dart 1.x to Dart 2, see the Dart 2 migration guides:

• Language and core library migration guide
• Web app migration guide