False positives for Dart APIs annotated with `@Deprecated.implement`

[LuuPNH]

🐛 False positives for Dart APIs annotated with @Deprecated.implement

Summary

SonarQ reports false positives for Dart APIs annotated with @Deprecated.implement, treating them as fully deprecated even when they are only instantiated or used, not implemented or extended.

This causes valid Dart code to be flagged incorrectly by rule
S1874 – Code annotated as deprecated should not be used.

SonarQ Issue

<Type> is deprecated and shouldn't be used.
This class will become 'final' in a future release.
<Interface> may be a more appropriate interface to implement.

Important distinction:

@Deprecated.implement applies only when a class implements or extends the annotated type

Expected behavior

• Do not flag usage or instantiation of APIs annotated with @Deprecated.implement

• Only flag cases where a class implements or extends those APIs

---

Environment

• SonarQube: v2025.1.4 (113907)
• Quality Profiles:Sonar way 2025-05-20
• Rule ID: dart:S1874
• Dart SDK: 3.10.1
• Flutter: 3.38.3

---

Example code triggering the issue

From the Dart SDK (dart:core)

@Deprecated.implement(
  "This class will become 'final' in a future release. "
  "'Pattern' may be a more appropriate interface to implement.",
)
abstract interface class RegExp implements Pattern {
   /// ...
}

Code triggering the issue

final regex = RegExp(r'\d+');
final isMatch = regex.hasMatch('123');

Issue message:

'RegExp' is deprecated and shouldn't be used. This class will become 'final' in a future release. 'Pattern' may be a more appropriate interface to implement. 

[trungnghia-bosch]

This issue also reproduced on my side with flutter version 3.38