tests/language/generic/super_bounded_types_and_variance_test.dart

// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// Testing that instantiate-to-bound and super-bounded types take the
// variance of formal type parameters into account when a type alias is
// used as a raw type.

// Standard type comparison support.

typedef F<X> = void Function<Y extends X>();
F<X> toF<X>(X x) => throw 0;

// Material specific to this test.

typedef Fcov<X> = X Function();
typedef Fcon<X> = Function(X);
typedef Finv<X> = X Function(X);

typedef FcovBound<X extends num> = X Function();
typedef FconBound<X extends num> = Function(X);
typedef FinvBound<X extends num> = X Function(X);

class A<X> {}

typedef FcovCyclicBound<X extends A<X>> = X Function();
typedef FconCyclicBound<X extends A<X>> = Function(X);
typedef FinvCyclicBound<X extends A<X>> = X Function(X);

typedef FcovCyclicCoBound<X extends Function(X)> = X Function();
typedef FconCyclicCoBound<X extends Function(X)> = Function(X);
typedef FinvCyclicCoBound<X extends Function(X)> = X Function(X);

class B<X> {}

void testTopLevel() {
  // I2b initial value for a covariant type parameter w/o bound: dynamic.
  void f1(Fcov source1) {
    var fsource1 = toF(source1);
    F<Fcov<dynamic>> target1 = fsource1;
  }

  // I2b initial value for a contravariant type parameter w/o bound: dynamic.
  void f2(Fcon source2) {
    var fsource2 = toF(source2);
    F<Fcon<dynamic>> target2 = fsource2;
  }

  // I2b initial value for an invariant type parameter w/o bound: dynamic.
  void f3(Finv source3) {
    var fsource3 = toF(source3);
    F<Finv<dynamic>> target3 = fsource3;
  }

  // I2b initial value for a covariant type parameter: bound.
  void f4(FcovBound source4) {
    var fsource4 = toF(source4);
    F<FcovBound<num>> target4 = fsource4;
  }

  // I2b initial value for a contravariant type parameter: bound.
  void f5(FconBound source5) {
    var fsource5 = toF(source5);
    F<FconBound<num>> target5 = fsource5;
  }

  // I2b initial value for an invariant type parameter: bound.
  void f6(FinvBound source6) {
    var fsource6 = toF(source6);
    F<FinvBound<num>> target6 = fsource6;
  }

  // I2b for a covariant type parameter w F-bound: Use bound, then break
  // cycle by replacing covariant occurrence by `dynamic`. Resulting type
  // is super-bounded: FcovCyclicBound<A<Never>> is regular-bounded.
  void f7(FcovCyclicBound source7) {
    var fsource7 = toF(source7);
    F<FcovCyclicBound<A<dynamic>>> target7 = fsource7;
  }

  // I2b for a contravariant type parameter w F-bound: Use bound, then break
  // cycle by replacing contravariant occurrence by `Never`. Resulting type
  // is super-bounded: FconCyclicBound<A<Object?>> is regular-bounded.
  void f8(FconCyclicBound source8) {
    var fsource8 = toF(source8);
    F<FconCyclicBound<A<Never>>> target8 = fsource8;
  }

  // I2b for an invariant type parameter w F-bound: Use bound, then break
  // cycle by replacing invariant occurrence by `dynamic`. Resulting type is
  // super-bounded: FinvCyclicBound<A<Never>> is regular-bounded.
  void f9(FinvCyclicBound source9) {
    var fsource9 = toF(source9);
    F<FinvCyclicBound<A<dynamic>>> target9 = fsource9;
  }

  // I2b for a covariant type parameter w F-bound: Use bound, then break
  // cycle by replacing contravariant occurrence by `Never`. Resulting type
  // is super-bounded: FcovCyclicBound<Function(Object?)> is regular-bounded.
  void f10(FcovCyclicCoBound source10) {
    var fsource10 = toF(source10);
    F<FcovCyclicCoBound<Function(Never)>> target10 = fsource10;
  }

  // I2b for a contravariant type parameter w F-bound: Use bound, then break
  // cycle by replacing covariant occurrence by `dynamic`. Resulting type
  // FconCyclicCoBound<Function(dynamic)> is regular-bounded.
  void f11(FconCyclicCoBound source11) {
    var fsource11 = toF(source11);
    F<FconCyclicCoBound<Function(dynamic)>> target11 = fsource11;
  }

  // I2b for an invariant type parameter w F-bound: Use bound, then break
  // cycle by replacing invariant occurrence by `dynamic`. Resulting type
  // F<FinvCyclicCoBound<Function(dynamic)>> is regular-bounded.
  void f12(FinvCyclicCoBound source12) {
    var fsource12 = toF(source12);
    F<FinvCyclicCoBound<Function(dynamic)>> target12 = fsource12;
  }
}

void testNested() {
  // Everything gets the same treatment when the cases from
  // `testTopLevel` are duplicated at the nested level.

  void f1(B<Fcov> source1) {
    var fsource1 = toF(source1);
    F<B<Fcov<dynamic>>> target1 = fsource1;
  }

  void f2(B<Fcon> source2) {
    var fsource2 = toF(source2);
    F<B<Fcon<dynamic>>> target2 = fsource2;
  }

  void f3(B<Finv> source3) {
    var fsource3 = toF(source3);
    F<B<Finv<dynamic>>> target3 = fsource3;
  }

  void f4(B<FcovBound> source4) {
    var fsource4 = toF(source4);
    F<B<FcovBound<num>>> target4 = fsource4;
  }

  void f5(B<FconBound> source5) {
    var fsource5 = toF(source5);
    F<B<FconBound<num>>> target5 = fsource5;
  }

  void f6(B<FinvBound> source6) {
    var fsource6 = toF(source6);
    F<B<FinvBound<num>>> target6 = fsource6;
  }

  void f7(B<FcovCyclicBound> source7) {
    var fsource7 = toF(source7);
    F<B<FcovCyclicBound<A<dynamic>>>> target7 = fsource7;
  }

  void f8(B<FconCyclicBound> source8) {
    var fsource8 = toF(source8);
    F<B<FconCyclicBound<A<Never>>>> target8 = fsource8;
  }

  void f9(B<FinvCyclicBound> source9) {
    var fsource9 = toF(source9);
    F<B<FinvCyclicBound<A<dynamic>>>> target9 = fsource9;
  }

  void f10(B<FcovCyclicCoBound> source10) {
    var fsource10 = toF(source10);
    F<B<FcovCyclicCoBound<Function(Never)>>> target10 = fsource10;
  }

  void f11(B<FconCyclicCoBound> source11) {
    var fsource11 = toF(source11);
    F<B<FconCyclicCoBound<Function(dynamic)>>> target11 = fsource11;
  }

  void f12(B<FinvCyclicCoBound> source12) {
    var fsource12 = toF(source12);
    F<B<FinvCyclicCoBound<Function(dynamic)>>> target12 = fsource12;
  }
}

main() {
  testTopLevel();
  testNested();
}