main.rs

trait T {}

struct A {}
struct B {}

impl T for A {}
impl T for B {}

fn main() {
    println!("Hello, world!");
    get();
}

fn get() -> [Option<(i32, Box<T>, i32)>; 2] {
    // let l: [Option<(i32, Box<T>, i32)>; 2] = [None; 2]; within `(i32, std::boxed::Box<T>, i32)`, the trait `std::marker::Copy` is not implemented for `std::boxed::Box<T>`
    let a: Box<(T)> = Box::new(A{});
    let b: Box<(T)> = Box::new(B{});
    let ta: Option<(i32, Box<T>, i32)> = Some((2, a, 3));
    let tb: Option<(i32, Box<T>, i32)> = Some((2, b, 3));

    [ta, tb] // use l instead
}