Initialize a fixed size array of structs

Question

I want to initialize an array of self defined structs automatically with a given rule.

With primitive types and types that implement Copy, I would do something like let x: [u8; 5] = [0; 5];, but with a type which can't derive Copy I have to do something else.

I probably could write down the whole list, but that is quite inconvenient, especially if I just want dummy values which will be altered later, equivalent to initializing an integer array with zeros.

I have tried a for loop like this

use std::collections::LinkedList;

enum CourseType {
    Dummy1,
    Dummy2,
}

struct Week {
    number: u64,
    days: [Day; 5], //Mo-Fr
}

struct Day {
    courses: LinkedList<Course>, // LinkedList prevents Copy
}

struct Course {
    beginning: u8,
    courseType: CourseType,
}

fn get_weeks() -> Option<Vec<Week>> {
    let mut weeks = Vec::with_capacity(20);
    for i in 1..14 {
        let week = Week {
            number: i,
            days: {
                let mut ret: [Day; 5]; // definition of the array
                for i in 0..4 {
                    // loop to initialize
                    ret[i] = Day {
                        courses: LinkedList::new(),
                    } //error[E0381]
                }
                ret //error[E0381]
            },
        };
        weeks.push(week);
    }
    Some(weeks)
}

As commented in the snippet, I get an error[E0381] by "initializing" this way:

error[E0381]: use of possibly uninitialized variable: `ret`
  --> src/main.rs:31:21
   |
31 | /                     ret[i] = Day {
32 | |                         courses: LinkedList::new(),
33 | |                     }
   | |_____________________^ use of possibly uninitialized `ret`

error[E0381]: use of possibly uninitialized variable: `ret`
  --> src/main.rs:35:17
   |
35 |                 ret
   |                 ^^^ use of possibly uninitialized `ret`

How would I initialize an array of this kind?

I have a fixed size of data in this case, since the (work)week only has 5 days. Using a dynamic type, like a vector, seems to be imprecise. I tried tuples before, but there I had a comparable problem where I had to iterate through the tuple indices. It seemed impossible (with variables) to address the index with a variable (something like tuple.index instead of e.g tuple.3).

Maybe I have to use some kind of a slice (&[Day; 5]) instead of an array, but I guess my understanding of Rust isn't quite there yet.