An undeclared crate, module, or type was used.
Erroneous code example:
let map = HashMap::new();
// error: failed to resolve: use of undeclared type `HashMap`Please verify you didn’t misspell the type/module’s name or that you didn’t forget to import it:
use std::collections::HashMap; // HashMap has been imported.
let map: HashMap<u32, u32> = HashMap::new(); // So it can be used!If you’ve expected to use a crate name:
use ferris_wheel::BigO;
// error: failed to resolve: use of undeclared crate or module `ferris_wheel`Make sure the crate has been added as a dependency in Cargo.toml.
To use a module from your current crate, add the crate:: prefix to the path.