error[E0433]: failed to resolve: maybe a missing crate `core`? --> $DIR/issue-102156.rs:4:5 | LL | use core::convert::{From, TryFrom}; | ^^^^ | | | maybe a missing crate `core`? | help: try using `std` instead of `core`: `std` error[E0433]: failed to resolve: maybe a missing crate `core`? --> $DIR/issue-102156.rs:4:5 | LL | use core::convert::{From, TryFrom}; | ^^^^ | | | maybe a missing crate `core`? | help: try using `std` instead of `core`: `std` | = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0433`.