Error code E0040

It is not allowed to manually call destructors in Rust.

Erroneous code example:

struct Foo {
    x: i32,
}

impl Drop for Foo {
    fn drop(&mut self) {
        println!("kaboom");
    }
}

fn main() {
    let mut x = Foo { x: -7 };
    x.drop(); // error: explicit use of destructor method
}
ⓘ

It is unnecessary to do this since drop is called automatically whenever a value goes out of scope. However, if you really need to drop a value by hand, you can use the std::mem::drop function:

struct Foo {
    x: i32,
}
impl Drop for Foo {
    fn drop(&mut self) {
        println!("kaboom");
    }
}
fn main() {
    let mut x = Foo { x: -7 };
    drop(x); // ok!
}