Error code E0254

Attempt was made to import an item whereas an extern crate with this name has already been imported.

Erroneous code example:

extern crate core; mod foo { pub trait core { fn do_something(); } } use foo::core; // error: an extern crate named `core` has already // been imported in this module fn main() {}

To fix this issue, you have to rename at least one of the two imports. Example:

extern crate core as libcore; // ok! mod foo { pub trait core { fn do_something(); } } use foo::core; fn main() {}