Rollup merge of #62514 - stephaneyfx:box-ffi, r=nikomatsakis

[rust.git] / src / librustc_error_codes / error_codes / E0635.md

The `#![feature]` attribute specified an unknown feature.

Erroneous code example:

```compile_fail,E0635
#![feature(nonexistent_rust_feature)] // error: unknown feature
```