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

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它只适用于Flutter 2.0.5。从Flutter 1.22.6flutter pub run build_runner build项目内部调用时，失败并显示以下错误消息：

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并flutter pub cache repair没有效果。所以问题是，需要做什么才能开始build_runner工作（现在已经过时了）Flutter version 1.22.6？非常欢迎您的建议，谢谢！

标签： flutterbuild-runner

解决方案

因为所需的第三方库阻止了迁移到 null 安全，所以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，不如说是一种解决方法，但这已经足够了。

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