[analyzer] ConvertToStateless should consider non-constant fields

[asashour]

import 'package:flutter/material.dart';

class Abc extends StatefulWidget {
  const Abc({super.key});

  @override
  State<Abc> createState() => _AbcState();
}

class _AbcState extends State<Abc> {
  GlobalKey<FormState> key = GlobalKey();

  @override
  Widget build(BuildContext context) => Container();
}

has an assist to convert it to

import 'package:flutter/material.dart';

class Abc extends StatelessWidget {
  const Abc({super.key});

  GlobalKey<FormState> key = GlobalKey();

  @override
  Widget build(BuildContext context) => Container();
}

which gives a compile error, because const constructor conflicts with the non-constant field.

In this case, it is better to also remove the const keyword. This would also lead to the necessity of the removal of const in the construction invocation, but that's outside the scope of the assist.

[bwilkerson]

I don't know how often this is impacting users, so the priority might need to be adjusted.

[bwilkerson]

In this case, it is better to also remove the const keyword.

It isn't clear to me whether we want to remove the const keyword or whether we want to not offer the assist in this case. The reason I think it might not be good to remove the const keyword is that doing so could introduce errors anywhere that the class is being instantiated in a constant context.

It's possible that when the new refactoring support is completed we might want to consider making this a refactoring (which would allow us to clean up visible use cases). (I'm not sure that's ideal either, but it's worth considering.)