Checks whether an interface is implemented multiple times.

It is a compile-time error if an interface appears multiple times
across the extends and implements clauses.

This CL implements a check to detect the aforementioned case. A
previous commit implemented this by expanding and refactoring the
restricted super types check in source_loader.dart
(c.f. checkSemantics method). The restricted super types check decides
whether a type is allowed to appear in an 'extends', 'implements', or
'with' clause. However, it turned out it may have sat too early in the
compilation pipeline as it failed to detect the following case

   class A implements Object {}

I decided that it was somewhat suboptimal to implement a special case
for "Object". Therefore I have moved the check to a later stage in the
pipeline, where classes without a super class have had the Object
class injected as their default super class. The check is now
implemented in kernel_class_builder.dart (c.f. checkSupertypes
method).

Closes https://github.com/dart-lang/sdk/issues/34193

Change-Id: Ie7153c896337b589118cac4b80e9df8ea5a09daa
Reviewed-on: https://dart-review.googlesource.com/70864
Commit-Queue: Daniel Hillerström <hillerstrom@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>
12 files changed
tree: c396d230835344d746ced889e98182b9bd542b89
  1. .github/
  2. build/
  3. client/
  4. docs/
  5. pkg/
  6. runtime/
  7. samples/
  8. samples-dev/
  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. .packages
  21. AUTHORS
  22. BUILD.gn
  23. CHANGELOG.md
  24. codereview.settings
  25. CONTRIBUTING.md
  26. dartdoc_options.yaml
  27. DEPS
  28. LICENSE
  29. PATENTS
  30. PRESUBMIT.py
  31. README.dart-sdk
  32. README.md
  33. WATCHLISTS
README.md

Dart

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Using Dart

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