.pub-cache/hosted/pub.flutter-io.cn/source_span-1.7.0/lib/src/file.dart:437:1: Error: This requires

/D:/rruanjian/flutter/.pub-cache/hosted/pub.flutter-io.cn/source_span-1.7.0/lib/src/file.dart:437:1: Error: This requires the 'extension-methods' experiment to be enabled.

Try enabling this experiment by adding it to the command line when compiling and running.

extension FileSpanExtension on FileSpan {

^^^^^^^^^

/D:/rruanjian/flutter/.pub-cache/hosted/pub.flutter-io.cn/source_span-1.7.0/lib/src/file.dart:437:32: Error: A function declaration needs an explicit list of parameters.

Try adding a parameter list to the function declaration.

extension FileSpanExtension on FileSpan {

                               ^^^^^^^^

用的最新版本一直报这错，我是把flutter的版本降了几个，好了