anchor.diff:  // SharedOptions=--enable-experiment=set-literals
   import "../../Utils/expect.dart";
   import "dart:collection";
  +
  +// Class overriding `==`.
  +class C {
  +  final int id;
  +  final String name;
  +  C(this.id, this.name);
  +  int get hashCode => id;
  +  bool operator==(Object other) => other is C && id == other.id;
  +  String toString() => "C($id, $name)";
  +}
   
   main() {
     Expect.isTrue({} is LinkedHashMap<dynamic, dynamic>);
  
positive.code:   var l18 = const {1, 2};
    Expect.isTrue(l18 is Set<int>);
  
    // Class overriding `==`.
    class C {
      final int id;
      final String name;
      C(this.id, this.name);
      int get hashCode => id;
      bool operator==(Object other) => other is C && id == other.id;
      String toString() => "C($id, $name)";
    }
  
    var v19 = {C(1, "a"), C(2, "a"), C("1", "b")};
    Expect.isTrue(l19 is LinkedHashSet<C>);
    Expect.equals({C(1, "a"), C(2, "a")}, v19);
  
    var v23 = {1, 2.5};
  
negative.code:   var v24 = {1, false};
    Expect.isTrue(v24 is LinkedHashSet<Object>);
    const v26  = {1, false};
    Expect.isTrue(v26 is Set<Object>);
  }
  