| A feature attribute named a feature that was disallowed in the compiler | |
| command line flags. | |
| Erroneous code example: | |
| ```ignore (can't specify compiler flags from doctests) | |
| #![feature(extern_item_impls)] | |
| //~^ error: the feature `extern_item_impls` | |
| // is not in the list of allowed features | |
| ``` | |
| Delete the offending feature attribute, or add it to the list of allowed | |
| features in the `-Z allow_features` flag. |