Understanding Rust Error E0447

Introduction

Rust Error E0447 occurs when the pub keyword is used inside a function. When the pub keyword is used within a function, it makes no sense as items defined inside a function cannot be accessed from its surrounding code. Using the pub keyword in this context is invalid and thus the compiler emits error E0447.

Example of Erroneous Code

#![allow(unused)]
fn main() {
    fn foo() {
        pub struct Bar; // error: visibility has no effect inside functions
    }
}

Solution

To resolve Rust Error E0447, remove the pub keyword from the struct definition within the function.

Example of Corrected Code

#![allow(unused)]
fn main() {
  fn foo() {
    struct Bar;
  }
}

Conclusion

Rust Error E0447 is caused by using the pub keyword within a function, which has no effect on the item's visibility. To fix this error, simply remove the pub keyword from the item's definition. Understanding how scope and visibility work in Rust is essential to prevent such errors. You can refer to the Rust documentation on Modules and Use to Control Scope and Privacy for more information.