Flutter use_build_context_synchronously and SearchDelegate.close after await - flutter

Question

My use case: I show a search UI the user can pick an item with - when the user taps an item, something async happens and depending on the result, close (https://api.flutter.dev/flutter/material/SearchDelegate/close.html) is called with either the picked item or a null. In my snippet below the async something is simply asking the user for confirmation with an AlertDialog.
This works without an issue but I updated the lint rules recently, and turned this one on: https://dart-lang.github.io/linter/lints/use_build_context_synchronously.html. Now the linter complains about the BuildContext being used after an await in the call to close. Here is the snippet (full reproducible sample below, written with Flutter 2.10.4):
onTap: () async {
final confirmed = await _confirm(context, item) ?? false;
// Triggers 'Do not use BuildContexts across async gaps.'
// https://dart-lang.github.io/linter/lints/use_build_context_synchronously.html
close(context, confirmed ? item : null);
},
I guess this makes sense and could be dangerous in some scenarios, so I'd better fix it. My question is: how do I implement my use case the 'right' way? One solution that works is to extract suggestions to a separate StatefulWidget and guard the call with a isMounted check, but this has the following drawbacks:
It requires a separate StatefulWidget that I would otherwise not need (boilerplate I don't want).
I need to pass a callback to the widget to call close (it belongs to SearchDelegate but now it will be called by code in the widget).
As close requires a BuildContext, I either have to pass the one that the SearchDelegate has to the widget to use (yuck) or just use the one from my widget - in this case it works (as close just uses Navigator.of(context)), but what if it were necessary to pass exactly the one from SearchDelegate?
Full code:
import 'package:flutter/material.dart';
void main() {
runApp(App());
}
class App extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: _Home(),
);
}
}
class _Home extends StatefulWidget {
#override
State<_Home> createState() => _HomeState();
}
class _HomeState extends State<_Home> {
String? _picked;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
TextButton(
onPressed: () => _maybePick(context),
child: const Text('Maybe pick'),
),
Center(
child: Text(_picked != null ? 'Last pick: $_picked' : 'No pick'),
),
],
),
);
}
Future<void> _maybePick(BuildContext context) async {
final result = await showSearch<String?>(
context: context,
delegate: _PickerDelegate(),
);
if (result != null) {
setState(() {
_picked = result;
});
}
}
}
class _PickerDelegate extends SearchDelegate<String?> {
final _allItems = List.generate(200, (index) => 'Item $index');
#override
Widget buildLeading(BuildContext context) {
return IconButton(
onPressed: () => close(context, null),
icon: const BackButtonIcon(),
);
}
#override
List<Widget> buildActions(BuildContext context) {
return [
IconButton(
onPressed: () => query = '',
icon: const Icon(Icons.clear),
),
];
}
#override
Widget buildSuggestions(BuildContext context) {
final items = _allItems.where((element) => element.contains(query));
return ListView(
children: items.map((item) {
return ListTile(
title: Text(item),
onTap: () async {
final confirmed = await _confirm(context, item) ?? false;
// Triggers 'Do not use BuildContexts across async gaps.'
// https://dart-lang.github.io/linter/lints/use_build_context_synchronously.html
close(context, confirmed ? item : null);
},
);
}).toList(growable: false),
);
}
#override
Widget buildResults(BuildContext context) {
// Keep it simple for the snippet.
throw UnimplementedError('results are not supported');
}
Future<bool?> _confirm(BuildContext context, String item) async {
return showDialog<bool>(
context: context,
builder: (context) {
return AlertDialog(
content: Text("Pick '$item'?"),
actions: [
TextButton(
onPressed: () => Navigator.of(context).pop(true),
child: const Text('Yes'),
),
TextButton(
onPressed: () => Navigator.of(context).pop(false),
child: const Text('No'),
),
],
);
},
);
}
}