LL | #![warn(rust_2018_compatibility)]
| ^^^^^^^^^^^^^^^^^^^^^^^
= note: `#[warn(keyword_idents)]` implied by `#[warn(rust_2018_compatibility)]`
- = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+ = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
= note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
warning: 1 warning emitted