library /*isNonNullableByDefault*/;
//
// Problems in library:
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:25:14: Error: The argument type 'B?' can't be assigned to the parameter type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   fooContext(x); // Error.
//              ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:26:9: Error: A value of type 'B?' can't be assigned to a variable of type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   A a = x; // Error.
//         ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:27:10: Error: Can't assign spread elements of type 'B?' to collection elements of type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   <A>[...l]; // Error.
//          ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:28:10: Error: An expression whose value can be 'null' must be null-checked before it can be dereferenced.
//   <A>[...l2]; // Error.
//          ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:29:13: Error: Can't assign spread entry keys of type 'B?' to map entry keys of type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   <A, A>{...m}; // Error.
//             ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:29:13: Error: Can't assign spread entry values of type 'B?' to map entry values of type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   <A, A>{...m}; // Error.
//             ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:30:13: Error: An expression whose value can be 'null' must be null-checked before it can be dereferenced.
//   <A, A>{...m2}; // Error.
//             ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:31:10: Error: A value of type 'B?' can't be assigned to a variable of type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
// Try changing the type of the variable.
//   for (A y in l) {} // Error.
//          ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:32:15: Error: The type 'List<B>?' used in the 'for' loop must implement 'Iterable<dynamic>' because 'List<B>?' is nullable and 'Iterable<dynamic>' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'Iterable' is from 'dart:core'.
//   for (A y in l2) {} // Error.
//               ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:34:16: Error: Type 'A' of the case expression is not a subtype of type 'B?' of this switch expression.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//     case const A():
//                ^
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:33:11: Context: The switch expression is here.
//   switch (x) /*  Error. */ {
//           ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:39:10: Error: A value of type 'B?' can't be returned from a function with return type 'A' because 'B?' is nullable and 'A' isn't.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   return x; // Error.
//          ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:43:14: Error: The argument type 'List<B?>' can't be assigned to the parameter type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   barContext(x); // Error.
//              ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:44:15: Error: A value of type 'List<B?>' can't be assigned to a variable of type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   List<A> y = x; // Error.
//               ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:45:16: Error: Can't assign spread elements of type 'List<B?>' to collection elements of type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   <List<A>>[...l]; // Error.
//                ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:46:25: Error: Can't assign spread entry keys of type 'List<B?>' to map entry keys of type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   <List<A>, List<A>>{...m}; // Error.
//                         ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:46:25: Error: Can't assign spread entry values of type 'List<B?>' to map entry values of type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   <List<A>, List<A>>{...m}; // Error.
//                         ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:47:16: Error: A value of type 'List<B?>' can't be assigned to a variable of type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
// Try changing the type of the variable.
//   for (List<A> y in l) {} // Error.
//                ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:48:10: Error: A value of type 'List<B?>' can't be returned from a function with return type 'List<A>' because 'B?' is nullable and 'A' isn't.
//  - 'List' is from 'dart:core'.
//  - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//  - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
//   return x; // Error.
//          ^
//
// pkg/front_end/testcases/nnbd/assignability_error_messages.dart:52:14: Error: The argument type 'num? Function()' can't be assigned to the parameter type 'num Function()' because 'num?' is nullable and 'num' isn't.
//   bazContext(c);
//              ^
//
import self as self;
import "dart:core" as core;

class A extends core::Object /*hasConstConstructor*/  {
  const constructor •() → self::A
    : super core::Object::•()
    ;
}
class B extends self::A {
  synthetic constructor •() → self::B
    : super self::A::•()
    ;
}
class C extends core::Object {
  synthetic constructor •() → self::C
    : super core::Object::•()
    ;
  method call() → core::num? {}
}
static method fooContext(self::A x) → void {}
static method barContext(core::List<self::A> x) → void {}
static method bazContext(() → core::num f) → void {}
static method foo(self::B? x, core::List<self::B?> l, core::Map<self::B?, self::B?> m, core::List<self::B>? l2, core::Map<self::B, self::B>? m2) → self::A {
  self::fooContext(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:25:14: Error: The argument type 'B?' can't be assigned to the parameter type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  fooContext(x); // Error.
             ^" in x);
  self::A a = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:26:9: Error: A value of type 'B?' can't be assigned to a variable of type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  A a = x; // Error.
        ^" in x;
  <self::A>[invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:27:10: Error: Can't assign spread elements of type 'B?' to collection elements of type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  <A>[...l]; // Error.
         ^"];
  <self::A>[invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:28:10: Error: An expression whose value can be 'null' must be null-checked before it can be dereferenced.
  <A>[...l2]; // Error.
         ^"];
  <self::A, self::A>{invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:29:13: Error: Can't assign spread entry keys of type 'B?' to map entry keys of type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  <A, A>{...m}; // Error.
            ^": invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:29:13: Error: Can't assign spread entry values of type 'B?' to map entry values of type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  <A, A>{...m}; // Error.
            ^"};
  <self::A, self::A>{invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:30:13: Error: An expression whose value can be 'null' must be null-checked before it can be dereferenced.
  <A, A>{...m2}; // Error.
            ^": null};
  {
    core::Iterator<self::B?> :sync-for-iterator = l.{core::Iterable::iterator};
    for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
      final self::B? #t3 = :sync-for-iterator.{core::Iterator::current};
      {
        self::A y = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:31:10: Error: A value of type 'B?' can't be assigned to a variable of type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
Try changing the type of the variable.
  for (A y in l) {} // Error.
         ^" in #t3;
      }
    }
  }
  {
    core::Iterator<dynamic> :sync-for-iterator = (let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:32:15: Error: The type 'List<B>?' used in the 'for' loop must implement 'Iterable<dynamic>' because 'List<B>?' is nullable and 'Iterable<dynamic>' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'Iterable' is from 'dart:core'.
  for (A y in l2) {} // Error.
              ^" in l2).{core::Iterable::iterator};
    for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
      self::A y = :sync-for-iterator.{core::Iterator::current};
      {}
    }
  }
  #L1:
  switch(x) {
    #L2:
    case #C1:
      {
        break #L1;
      }
    #L3:
    default:
      {
        break #L1;
      }
  }
  return let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:39:10: Error: A value of type 'B?' can't be returned from a function with return type 'A' because 'B?' is nullable and 'A' isn't.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  return x; // Error.
         ^" in x;
}
static method bar(core::List<self::B?> x, core::List<core::List<self::B?>> l, core::Map<core::List<self::B?>, core::List<self::B?>> m) → core::List<self::A> {
  self::barContext(let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:43:14: Error: The argument type 'List<B?>' can't be assigned to the parameter type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  barContext(x); // Error.
             ^" in x);
  core::List<self::A> y = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:44:15: Error: A value of type 'List<B?>' can't be assigned to a variable of type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  List<A> y = x; // Error.
              ^" in x;
  <core::List<self::A>>[invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:45:16: Error: Can't assign spread elements of type 'List<B?>' to collection elements of type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  <List<A>>[...l]; // Error.
               ^"];
  <core::List<self::A>, core::List<self::A>>{invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:46:25: Error: Can't assign spread entry keys of type 'List<B?>' to map entry keys of type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  <List<A>, List<A>>{...m}; // Error.
                        ^": invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:46:25: Error: Can't assign spread entry values of type 'List<B?>' to map entry values of type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  <List<A>, List<A>>{...m}; // Error.
                        ^"};
  {
    core::Iterator<core::List<self::B?>> :sync-for-iterator = l.{core::Iterable::iterator};
    for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
      final core::List<self::B?> #t9 = :sync-for-iterator.{core::Iterator::current};
      {
        core::List<self::A> y = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:47:16: Error: A value of type 'List<B?>' can't be assigned to a variable of type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
Try changing the type of the variable.
  for (List<A> y in l) {} // Error.
               ^" in #t9;
      }
    }
  }
  return let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:48:10: Error: A value of type 'List<B?>' can't be returned from a function with return type 'List<A>' because 'B?' is nullable and 'A' isn't.
 - 'List' is from 'dart:core'.
 - 'B' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
 - 'A' is from 'pkg/front_end/testcases/nnbd/assignability_error_messages.dart'.
  return x; // Error.
         ^" in x;
}
static method baz(self::C c) → void {
  self::bazContext(let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/assignability_error_messages.dart:52:14: Error: The argument type 'num? Function()' can't be assigned to the parameter type 'num Function()' because 'num?' is nullable and 'num' isn't.
  bazContext(c);
             ^" in let final self::C #t13 = c in #t13.==(null) ?{() → core::num?} null : #t13.{self::C::call});
}
static method main() → dynamic {}

constants  {
  #C1 = self::A {}
}