| library /*isNonNullableByDefault*/; | 
 | // | 
 | // Problems in library: | 
 | // | 
 | // pkg/front_end/testcases/general/covariant_super_check.dart:16:27: Error: The parameter 'a' of the method 'C.method' has type 'String', which does not match the corresponding type, 'num', in the overridden method, 'A.method'. | 
 | // Change to a supertype of 'num', or, for a covariant parameter, a subtype. | 
 | //   method(covariant String a) {} | 
 | //                           ^ | 
 | // pkg/front_end/testcases/general/covariant_super_check.dart:6:3: Context: This is the overridden method ('method'). | 
 | //   method(num a) {} | 
 | //   ^ | 
 | // | 
 | import self as self; | 
 | import "dart:core" as core; | 
 |  | 
 | class A extends core::Object { | 
 |   synthetic constructor •() → self::A | 
 |     ; | 
 |   method method(core::num a) → dynamic | 
 |     ; | 
 | } | 
 | class B extends self::A { | 
 |   synthetic constructor •() → self::B | 
 |     ; | 
 |   method method(dynamic a) → dynamic | 
 |     ; | 
 | } | 
 | class C extends self::B { | 
 |   synthetic constructor •() → self::C | 
 |     ; | 
 |   method method(covariant-by-declaration core::String a) → dynamic | 
 |     ; | 
 | } | 
 | static method main() → dynamic | 
 |   ; |