Question

我已将 // @dart=2.9 添加到我的所有文件中，但 build_runner 不会在不抛出此错误的情况下执行其操作：

Warning: Operand of null-aware operation '?.' has type 'SendPort' which excludes null. - 'SendPort' is from 'dart:isolate'.  sendPort?.send(result);  ^Error: Cannot run with sound null safety, because the following dependencies don't support null safety: 
- package:build_runner_core 
- package:json_serializable 
- package:moor_generator 
- package:objectbox_generator 
- package:retrofit_generator 
- package:source_gen 
- package:build_config 
- package:build_runner 
- package:build 
- package:json_annotation 
- package:glob 
- package:pool 
- package:crypto 
- package:logging 
- package:watcher 
- package:build_resolvers 
- package:timing 
- package:graphs 
- package:package_config 
- package:yaml 
- package:analyzer 
- package:sqlparser 
- package:objectbox 
- package:dart_style 
- package:built_collection 
- package:code_builder 
- package:dio 
- package:tuple 
- package:retrofit 
- package:pedantic 
- package:checked_yaml 
- package:pubspec_parse 
- package:build_daemon 
- package:args 
- package:io 
- package:convert 
- package:pub_semver 
- package:ffi 
- package:quiver 
- package:moor 
- package:recase 
- package:_fe_analyzer_shared 
- package:built_value 
- package:http_parser 
- package:http_multi_server 
- package:shelf 
- package:stream_transform 
- package:mime 
- package:shelf_web_socket 
- package:web_socket_channel 
- package:cli_util 
- package:fixnum 
- package:synchronizedFor solutions, see https://dart.dev/go/unsound-null-safety.dart_tool/build/entrypoint/build.dart:44:44: Error: The parameter 'sendPort' can't have a value of 'null' because of its type 'SendPort', but the implicit default value is 'null'. - 'SendPort' is from 'dart:isolate'.Try adding either an explicit non-'null' default value or the 'required' modifier.void main(List<String> args, [_i8.SendPort sendPort]) async {

Answer 1

请确保您的所有软件包都更新为各自的空安全版本。对于构建运行程序，请使用 ^1.12.2，然后在当前工作目录中的终端中运行以下命令。

flutter clean
flutter pub cache repair
flutter pub run build_runner clean
flutter pub get

然后运行 build runner 命令。

这对我有用，我已经使用构建运行器成功生成了文件。

Answer 2

删除flutter文件夹内的.pub-cache文件夹，然后运行pub upgrade，之后你应该可以运行：

flutter packages pub run build_runner build --delete-conflicting-outputs

Answer 3

对于那些正在使用完整的 null-safety 的人，即没有使用 @dart=2.9 或其他方式来忽略 null-safety。

在您的 pubspec.yaml 文件中，较低的 SDK 版本应为 >=2.12。

environment:
  sdk: '>=2.12.0 <3.0.0'

使用以下版本（都是空安全的）

json_annotation: ^4.0.1
json_serializable: ^4.1.2
build_runner: ^2.0.3

我迁移到空安全，我不能运行“flutter pub run build_runner build”而不抛出错误

3 个答案: