json_serializable disregards the page_width setting in analysis_options.yaml and uses the default value of 80. Therefore, if a different page_width is specified in the project's analysis_options.yaml, a separate formatting step is required after running build_runner build.

Steps to Reproduce

This behavior can be reproduced in the json_serializable.dart project.

1. Set a page_width value other than 80 in /analysis_options.yaml:

   formatter:
     page_width: 120

2. Navigate to the /example.
3. Run dart run build_runner build -d.
   • The generated code is formatted with page_width 80.
4. Run dart format lib/.
   • The generated code is formatted with page_width 120.
5. Run dart run build_runner build -d.
   • The generated code is formatted with page_width 80.

Proposal

How about adding the line // dart format width=80 to the generated code?

https://github.com/dart-lang/dart_style/blob/bacc9bf8fcec6fffc15ad7e9257b7faba5298ea9/CHANGELOG.md#300

Trailing comma

As reported in #1486, the trailing commas option is also not reflected. However, since commas are removed when formatted with TrailingCommas.automate, I cannot think of any cases where additional formatting would be necessary.