The name for an item declaration conflicts with an external crate's name.

Erroneous code example:

```compile_fail,E0260
extern crate core;

struct core;

fn main() {}
```

There are two possible solutions:

Solution #1: Rename the item.

```
extern crate core;

struct xyz;
```

Solution #2: Import the crate with a different name.

```
extern crate core as xyz;

struct abc;
```

See the Declaration Statements section of the reference for more information
about what constitutes an Item declaration and what does not:

https://doc.rust-lang.org/reference.html#statements