Add MissingSdkLibraryResult and centralize SDK checks

Introduce a dedicated result type, `MissingSdkLibraryResult`, returned
when required SDK libraries (e.g., `dart:core`, `dart:async`) are not
available. The analysis driver now detects missing SDK libraries early
and completes all pending requests for the affected library with this
typed result.

What changes
- New public API:
  - `abstract class MissingSdkLibraryResult` (exposes `missingUri`)
  - `MissingSdkLibraryResultImpl` implementation
- Driver behavior:
  - New helper `_completeRequestsIfMissingSdkLibrary(...)` short-circuits
    analysis when `dart:core` or `dart:async` is missing, completing:
    - `getErrors`, `getResolvedUnit`, `getResolvedLibrary`,
      `getUnitElement`, `getLibraryByUri` with `MissingSdkLibraryResult`
    - `getIndex` with `null` for index data
  - Removes duplicated per-call checks and ad-hoc error creation
- Result printing updated to render `MissingSdkLibraryResult`
- Old path that produced an `ErrorsResult` with a synthetic
  `missingDartLibrary` diagnostic is removed

Why
- Provide a clear, explicit signal to callers that the SDK is incomplete
- Unify behavior across APIs and reduce duplicated logic
- Avoid relying on temporary diagnostics for a systemic environment issue

Behavioral / API notes
- Calls that previously could yield an `ErrorsResult` containing a
  synthetic “missing SDK library” diagnostic will now return
  `MissingSdkLibraryResult`. Clients should handle this result type and
  surface the `missingUri` to users as appropriate.

Change-Id: Ib71ceb05269d5b9fe4276a03155278aef64daf56
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/447005
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
6 files changed
tree: 7bc6a68d11039ead445f6c59b2a74f0699df8a28
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. docs/
  6. pkg/
  7. runtime/
  8. samples/
  9. sdk/
  10. tests/
  11. third_party/
  12. tools/
  13. utils/
  14. .clang-format
  15. .gitattributes
  16. .gitconfig
  17. .gitignore
  18. .gn
  19. .mailmap
  20. .style.yapf
  21. AUTHORS
  22. BUILD.gn
  23. CHANGELOG.md
  24. codereview.settings
  25. CONTRIBUTING.md
  26. DEPS
  27. LICENSE
  28. OWNERS
  29. PATENT_GRANT
  30. PRESUBMIT.py
  31. pubspec.yaml
  32. README.dart-sdk
  33. README.md
  34. sdk.code-workspace
  35. sdk_args.gni
  36. sdk_packages.yaml
  37. SECURITY.md
  38. WATCHLISTS
README.md

Dart

An approachable, portable, and productive language for high-quality apps on any platform

Dart is:

  • Approachable: Develop with a strongly typed programming language that is consistent, concise, and offers modern language features like null safety and patterns.

  • Portable: Compile to ARM, x64, or RISC-V machine code for mobile, desktop, and backend. Compile to JavaScript or WebAssembly for the web.

  • Productive: Make changes iteratively: use hot reload to see the result instantly in your running app. Diagnose app issues using DevTools.

Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:

  • Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

  • Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).

Dart platforms illustration

License & patents

Dart is free and open source.

See LICENSE and PATENT_GRANT.

Using Dart

Visit dart.dev to learn more about the language, tools, and to find codelabs.

Browse pub.dev for more packages and libraries contributed by the community and the Dart team.

Our API reference documentation is published at api.dart.dev, based on the stable release. (We also publish docs from our beta and dev channels, as well as from the primary development branch).

Building Dart

If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.

There are more documents in our repo at docs.

Contributing to Dart

The easiest way to contribute to Dart is to file issues.

You can also contribute patches, as described in Contributing.

Roadmap

Future plans for Dart are included in the combined Dart and Flutter roadmap on the Flutter wiki.