---

name: deprecated-api-detection description: Detects and flags deprecated Flutter/Dart APIs, suggests modern equivalents. Use when reviewing code, refactoring, or ensuring code uses modern APIs.

Deprecated API Detection

Mandatory Rule

✅ Zero deprecated API warnings - always use modern Flutter/Dart APIs ✅ Check Flutter/Dart migration guides for modern equivalents

Common Deprecations

Flutter Widgets

❌ Deprecated:

CopyRaisedButton(
  onPressed: () {},
  child: Text('Click'),
)

✅ Modern:

CopyElevatedButton(
  onPressed: () {},
  child: Text('Click'),
)

Flutter Testing

❌ Deprecated:

Copytester.binding.window.physicalSize = Size(800, 600);

✅ Modern:

Copytester.view.physicalSize = Size(800, 600);

Flutter Text Theme

❌ Deprecated:

CopyTheme.of(context).textTheme.headline

✅ Modern:

CopyTheme.of(context).textTheme.headlineMedium

Detection Methods

IDE Warnings

Most IDEs highlight deprecated APIs automatically:

• Yellow squiggly lines
• Deprecation warnings in Problems panel
• Hover tooltips showing deprecation info

Static Analysis

Run static analysis to detect deprecations:

Copyflutter analyze
dart analyze

Migration Guides

Check Flutter/Dart migration guides for common deprecations:

• Flutter Migration Guide
• Dart Migration Guide
• Breaking Changes documentation

Modern API Patterns

Material 3

Use Material 3 widgets when available:

Copy// ✅ Modern Material 3
Card(
  elevation: 0, // Use shadowColor instead
  shape: RoundedRectangleBorder(...),
)

Null Safety

Use null-safe APIs:

Copy// ✅ Modern null-safe
String? getValue() => _value;
final result = getValue() ?? 'default';

Async/Await

Use async/await instead of deprecated patterns:

Copy// ✅ Modern async/await
Future<String> fetchData() async {
  return await repository.getData();
}

Refactoring Pattern

When encountering deprecated API:

1. Identify deprecation - Read deprecation message
2. Find modern equivalent - Check migration guide
3. Update code - Replace with modern API
4. Test changes - Verify behavior unchanged
5. Remove old code - Clean up deprecated usage

Common Deprecations Checklist

• No RaisedButton (use ElevatedButton)
• No FlatButton (use TextButton)
• No OutlineButton (use OutlinedButton)
• No tester.binding.window (use tester.view)
• No deprecated text theme names (use headlineMedium not headline)
• No deprecated HTTP methods
• No deprecated image loading APIs
• No deprecated route APIs

Tools

• Flutter analyze - Detects deprecations
• IDE warnings - Highlights deprecated APIs
• Migration guides - Provides modern equivalents

Reference

• Flutter Migration Guide
• Dart Migration Guide
• Breaking Changes documentation