Fix 'covariant' bit propagation in mixin applications

In the upstream CL https://dart-review.googlesource.com/c/sdk/+/100580 the
'covariant' bit on parameters of class methods isn't propagated correctly in the
case of mixins.  Effectively, if it's used in a member of the superclass of the
mixin application, it won't be propagated to the mixin application or its
subclasses.  Consider the following:

```
class A {
  void foo(covariant num x) {}
}

class B {
  void foo(num x) {}
}

class C {
  void foo(num x) {}
}

class D extends A with B implements C {
  void foo(int x) {}
}
```

The program above doesn't have any errors, and overriding foo in D using int as
the type of the parameter is allowed, because D's superclass A declares the
parameter as 'covariant'.  Without the changes from this CL, the code will
result in a compile-time error.  With the change, the 'covariant' bit is
propagated correctly, and the program compiles.

An existing test already covers the described behavior: see class Mixed in
tests/language_2/covariant_override/tear_off_type_test.dart.

Change-Id: Ia508a224527c95f5ef04c1f1fb02614f8ff43714
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/101284
Reviewed-by: Aske Simon Christensen <askesc@google.com>
15 files changed
tree: a5169d04e60a57025f8daeee8fc4018880765dca
  1. .clang-format
  2. .gitattributes
  3. .gitconfig
  4. .github/
  5. .gitignore
  6. .gn
  7. .mailmap
  8. .packages
  9. .vpython
  10. AUTHORS
  11. BUILD.gn
  12. CHANGELOG.md
  13. CONTRIBUTING.md
  14. DEPS
  15. LICENSE
  16. PATENTS
  17. PRESUBMIT.py
  18. README.dart-sdk
  19. README.md
  20. WATCHLISTS
  21. build/
  22. client/
  23. codereview.settings
  24. docs/
  25. pkg/
  26. runtime/
  27. samples-dev/
  28. samples/
  29. sdk/
  30. tests/
  31. third_party/
  32. tools/
  33. utils/
README.md

Dart

A client-optimized language for fast apps on any platform

Dart is:

  • Optimized for UI: Develop with a programming language specialized around the needs of user interface creation

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