| A type dependency cycle has been encountered. | |
| Erroneous code example: | |
| ```compile_fail,E0391 | |
| trait FirstTrait : SecondTrait { | |
| } | |
| trait SecondTrait : FirstTrait { | |
| } | |
| ``` | |
| The previous example contains a circular dependency between two traits: | |
| `FirstTrait` depends on `SecondTrait` which itself depends on `FirstTrait`. |