Rust error E0260: the name `core` is defined multiple times

What rustc prints

error[E0260]: the name `core` is defined multiple times
 --> main.rs:3:1
  |
1 | extern crate core;
  | ------------------ previous import of the extern crate `core` here
2 |
3 | struct core;
  | ^^^^^^^^^^^^ `core` redefined here
  |
  = note: `core` must be defined only once in the type namespace of this module
help: you can use `as` to change the binding name of the import
  |
1 | extern crate core as other_core;
  |                   +++++++++++++

Real output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.

extern crate core;

struct core;

fn main() {}

extern crate core;

struct xyz;

extern crate core as xyz;

struct abc;

Related errors

• E0425cannot find value in this scope
• E0603is private
• E0432unresolved import
• E0005refutable pattern in local binding
• E0255the name `foo` is defined multiple times
• E0259the name `core` is defined multiple times
• E0365`foo` is only public within the crate, and cannot be re-exported outside
• E0423cannot find function, tuple struct or tuple variant `Foo` in this scope

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