如何修复 Flutter build_runner 错误：无法预编译 build_runner:build_runner：

Posted 2023-04-14

【中文标题】如何修复 Flutter build_runner 错误：无法预编译 build_runner:build_runner：

【英文标题】：How to fix Flutter build_runner error: Failed to precompile build_runner:build_runner:

【发布时间】：2021-08-03 17:19:15

【问题描述】：

我正在开发两个 Flutter 项目，其中一个已经迁移到 null 安全并使用 Flutter 2.0.5。第二个项目，即导致问题的项目，尚未迁移到 null 安全性并使用 Flutter 1.22.6。只需重命名 Flutter SDK 文件夹即可切换项目。

现在的问题是 build_runner 仅适用于 Flutter 2.0.5。从 Flutter 1.22.6 项目内部调用 flutter pub run build_runner build 时，失败 带有以下错误消息：

Failed to precompile build_runner:build_runner:
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/http_multi_server-2.1.0/lib/src/multi_headers.dart:97:8: Error: The method 'MultiHeaders.add' has fewer named arguments than those of overridden method 'HttpHeaders.add'.
  void add(String name, Object value) 
       ^
org-dartlang-sdk:///sdk/lib/_http/http.dart:698:8: Context: This is the overridden method ('add').
  void add(String name, Object value,
       ^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/http_multi_server-2.1.0/lib/src/multi_headers.dart:129:8: Error: The method 'MultiHeaders.set' has fewer named arguments than those of overridden method 'HttpHeaders.set'.
  void set(String name, Object value) 
       ^
org-dartlang-sdk:///sdk/lib/_http/http.dart:707:8: Context: This is the overridden method ('set').
  void set(String name, Object value,
       ^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/build_runner-1.11.0/lib/src/entrypoint/runner.dart:23:31: Error: No named parameter with the name 'usageLineLength'.
  final argParser = ArgParser(usageLineLength: lineLength);
                              ^^^^^^^^^^^^^^^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/args-1.4.4/lib/src/arg_parser.dart:43:11: Context: Found this candidate, but the arguments don't match.
  factory ArgParser(bool allowTrailingOptions: true) =>
          ^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/build_runner-1.11.0/bin/src/commands/clean.dart:18:31: Error: No named parameter with the name 'usageLineLength'.
  final argParser = ArgParser(usageLineLength: lineLength);
                              ^^^^^^^^^^^^^^^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/args-1.4.4/lib/src/arg_parser.dart:43:11: Context: Found this candidate, but the arguments don't match.
  factory ArgParser(bool allowTrailingOptions: true) =>
          ^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/build_runner-1.11.0/bin/src/commands/generate_build_script.dart:18:31: Error: No named parameter with the name 'usageLineLength'.
  final argParser = ArgParser(usageLineLength: lineLength);
                              ^^^^^^^^^^^^^^^
../../../Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/args-1.4.4/lib/src/arg_parser.dart:43:11: Context: Found this candidate, but the arguments don't match.
  factory ArgParser(bool allowTrailingOptions: true) =>

奇怪的是，所有这些错误都在项目之外。 调用flutter clean 和flutter pub cache repair 无效。所以问题是，需要做什么才能让build_runner 继续工作（现在已经过时）Flutter version 1.22.6？ 非常欢迎您的建议，谢谢！

【参考方案1】：

由于必需的第三方库阻止迁移到 null 安全，唯一的解决方案是通过从生成的 json 切换到手写的来消除 build_runner。

与其说是解决方案，不如说是一种变通方法，但已经足够了。