Including an internal module produces "maybe a missing crate `module2`"

user_6449910 0
Viewed 785

I have the following project structure:

src
├── module1
│   └── mod.rs
├── main.rs
└── module2
    └── mod.rs

but I get a

error[E0432]: unresolved import `crate::module2`
 --> src/module2/mod.rs:6:14
  |
6 |   use crate::module2::SomeStruct;
  |              ^^^^^^^ maybe a missing crate `module2`?

When the contents of the files as as follows.

src/module1/mod.rs

pub mod module1 {

  // -- snip --

  use crate::module2::SomeStruct;

  }

  // -- snip --

}

src/module2/mod.rs

pub mod module2 {

  // --snip--

  pub struct SomeStruct;

  }

  // -- snip--

}

src/main.rs

mod module1;

fn main() {
  // -- snip--
}

Why is this and how can it be fixed? All relevant modules and structs are public. A relevant chapter in the Rust Book.

rust compiler-errors import module
1 Answers

The declaration of a module (e.g. pub mod module1) happens outside of that module. There are two kinds of module declarations: one where the definition is right after (inside braces), and one where the definition is in another file.

For modules in a separate file, you'll simply say pub mod module1; in that module's parent. For your structure, you'll want to have pub mod module1; and pub mod module2 in main.rs.

Inside the module file (e.g. src/module1/mod.rs), you don't need pub mod module1 at all. You can just have its items directly in the file.

So your setup should be

src/main.rs

pub mod module1;
pub mod module2;

src/module1/mod.rs

// -- snip --

use crate::module2::SomeStruct;

// -- snip

src/module2/mod.rs

// --snip--

pub struct SomeStruct;

// -- snip--
user_46392730
Related