[Breaking Change] dart:mirrors is deprecated in Dart 3.14 and scheduled for removal in Dart 4.0
>The Dart core library `dart:mirrors` is formally deprecated starting in the November 2026 stable release (Dart 3.14), with complete removal planned for Dart 4.0.
>As of Dart SDK commit 2d4ba07 (https://dart-review.googlesource.com/c/sdk/+/541360), `dart:mirrors` is annotated with `@deprecated` on `main`.
>Timeline:
- Dart 3.14 (November 2026): Importing `dart:mirrors` emits deprecation warnings, while continuing to execute on the standalone Dart VM throughout Dart 3.x.
>- Dart 4.0: `dart:mirrors` will be removed from the Dart SDK.
>Recommended Alternatives & Common Migrations:
- Resolving Package or Script Paths: Replace `currentMirrorSystem().findLibrary(...)` or `ClosureMirror.function.location` file lookups with `Isolate.resolvePackageUriSync(Uri.parse('package:foo/foo.dart'))` (`dart:isolate`) or `Platform.script` (`dart:io`).
>- Static Code Inspection (Tests & Tooling): Replace `reflectClass` / `LibraryMirror` declaration checks in tests and linters with `package:analyzer` (`parseString` from `package:analyzer/dart/analysis/utilities.dart` for fast single-file AST inspection, or `AnalysisContextCollection` when resolved element types are needed).
>- Enums, Dispatch & Test Runners: Replace reflective enum iteration and string-based method dispatch (`InstanceMirror.invoke`) with built-in `Enum.values` / `.byName()`, exhaustive `switch` expressions, and standard `package:test` `group()` / `test()` blocks.
>- Code Generation: Use `package:build`, `package:build_runner`, and `package:source_gen` (or `json_serializable`, `built_value`, `freezed`) for serialization, dependency injection, and boilerplate generation.
>- Ahead-of-Time Reflection: For workloads requiring reflection-like runtime capabilities, use pre-generated reflection via `package:reflectable` and `package:reflectable_builder`.
>Full details and discussion:
https://github.com/dart-lang/sdk/issues/44489