| library; | 
 | // | 
 | // Problems in library: | 
 | // | 
 | // pkg/front_end/testcases/extensions/builtin_identifiers.dart:5:11: Error: Can't use 'mixin' as a name here. | 
 | // extension mixin on int {} | 
 | //           ^^^^^ | 
 | // | 
 | // pkg/front_end/testcases/extensions/builtin_identifiers.dart:7:11: Error: Can't use 'extension' as a name here. | 
 | // extension extension on int {} | 
 | //           ^^^^^^^^^ | 
 | // | 
 | // pkg/front_end/testcases/extensions/builtin_identifiers.dart:9:11: Error: Can't use 'as' as a name here. | 
 | // extension as on int {} | 
 | //           ^^ | 
 | // | 
 | import self as self; | 
 | import "dart:core" as core; | 
 |  | 
 | extension mixin on core::int { | 
 | } | 
 | extension extension on core::int { | 
 | } | 
 | extension as on core::int { | 
 | } | 
 | static method main() → void {} |