| #### Note: this error code is no longer emitted by the compiler. | |
| A `#![feature]` attribute was declared for a feature that is stable in the | |
| current edition, but not in all editions. | |
| Erroneous code example: | |
| ```compile_fail | |
| #![feature(rust_2018_preview)] | |
| #![feature(test_2018_feature)] // error: the feature | |
| // `test_2018_feature` is | |
| // included in the Rust 2018 edition | |
| ``` |