Flutter/Dart Null 安全迁移

Question

我正在尝试迁移我的 Flutter/Dart 项目以使用空安全。我已经更新了所有依赖项并将 sdk 更改为使用“>=2.12.0 <3.0.0”。但是，当我尝试使用迁移工具时，出现以下错误：

当我查看我的 flutter 和 dart 版本时，一切似乎都很好。我可能看错了，但以下是 flutter doctor 和 brew info dart 的输出：

% flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.0.6, on macOS 11.4 20F71 darwin-x64, locale en-US)
[!] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
! Some Android licenses not accepted.  To resolve this, run: flutter doctor -- 
android-licenses
[✓] Xcode - develop for iOS and macOS
[✓] Chrome - develop for the web
[✓] Android Studio (version 4.0)
[✓] VS Code (version 1.57.0)
[✓] Connected device (2 available)

! Doctor found issues in 1 category.
 % brew info dart
dart-lang/dart/dart: stable 2.12.4, HEAD
The Dart SDK
https://dart.dev
Conflicts with:
  dart-beta (because dart-beta ships the same binaries)
/usr/local/Cellar/dart/2.9.3 (509 files, 523.7MB) *
  Built from source on 2020-09-14 at 16:52:16
From: https://github.com/dart-lang/homebrew-dart/blob/HEAD/dart.rb
==> Options
--HEAD
        Install HEAD version
==> Caveats
Please note the path to the Dart SDK:
  /usr/local/opt/dart/libexec

我怀疑我可能没有像我相信的那样拥有最新的 dart sdk。如果是这种情况，我该如何升级而不破坏任何东西？

更新：

看来我正在使用最新版本的 dart。进入 Android Studio 中的设置，我可以看到它指向带有 flutter 的 dart sdk：

Answer 1

您是否在终端中运行了“flutter upgrade”？