从 Dart 2 开始，pub 不再支持 pub build、pub serve 以及变换器。它们均由 build_runner 工具中的 build system 替代。

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.

有关在 Dart 2 中构建和提供应用的更多信息请查阅：

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

• build_runner 文档

  build_runner documentation

• 编译系统文档，包括 开始使用 build_runner

  Build system documents, including getting started with build_runner

获取从 Dart 1 切换到 Dart 2 的帮助请查阅：

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

• 语言和核心库迁移指南

  Language and core library migration guide

• Web 应用迁移指南

  Web app migration guide