Declarations ​

Each unused statement is tried not to be included in the C++ output. This does not pose much of a problem with global declarations and should not be a hindrance to compilation. But you have to use the declarations you make in your code blocks, if you don't the compiler will throw an error for each one.

For example:

fn main() {
    let a: int = 0
}

The variable a seen is declared but unused. This will cause you to get an error by the compiler and not be able to compile the code.