Rust error E0523: #### Note: this error code is no longer emitted by the compiler

The compiler team's explanation

Note: this error code is no longer emitted by the compiler.

The compiler found multiple library files with the requested crate name.

// aux-build:crateresolve-1.rs
// aux-build:crateresolve-2.rs
// aux-build:crateresolve-3.rs

extern crate crateresolve;
//~^ ERROR multiple candidates for `rlib` dependency `crateresolve` found

fn main() {}

This error can occur in several different cases -- for example, when using extern crate or passing --extern options without crate paths. It can also be caused by caching issues with the build directory, in which case cargo clean may help.

In the above example, there are three different library files, all of which define the same crate name. Without providing a full path, there is no way for the compiler to know which crate it should use.

*Note that E0523 has been merged into E0464.*

From rustc --explain E0523 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.