Formatter behavior changes with line comment inside parameter list

[lukehutch]

With an inline comment, the last two parameters here get put on the same line, which shouldn't be the case, since the last parameter has a trailing comma:

        await _loadProfileView(
          userId: profileView.userId,
          setLikeActionType: LikeActionType.block,
          // Remove star too from any user that is blocked
          setStarAction: false, onUserActionChanged: widget.onUserActionChanged,
        );

Removing the comment, the last two parameters get put on separate lines, as expected:

        await _loadProfileView(
          userId: profileView.userId,
          setLikeActionType: LikeActionType.block,
          setStarAction: false,
          onUserActionChanged: widget.onUserActionChanged,
        );

Dart version: 3.3.0-91.0.dev

[munificent]

This is working as intended but I'm not sure at all if it's working as desired. When an argument list has a trailing comma, the formatter currently treats it exactly like a collection literal. Collection literals have some special logic where a comment inside the literal triggers a rule where it preserves the newlines and allows multiple elements/arguments on the same line.

That's probably not the most useful behavior for an argument list, though. We're working on a rewrite of the formatter (#1253) which will likely revisit this behavior. In the meantime, if you add a newline yourself between the last two arguments, it will preserve it.