1 error[E0659]: `core` is ambiguous
2 --> $DIR/issue-57539.rs:4:9
7 = note: ambiguous because of multiple potential import sources
8 = note: `core` could refer to a built-in crate
9 = help: use `::core` to refer to this crate unambiguously
10 note: `core` could also refer to the module imported here
11 --> $DIR/issue-57539.rs:5:9
15 = help: use `self::core` to refer to this module unambiguously
17 error: aborting due to previous error
19 For more information about this error, try `rustc --explain E0659`.