TY: Introduce array of unknown size

This code is ok, but syntax checker marks array as wrong

const COUNT: usize = 2;

struct Foo {
    v: [usize; COUNT]
}

fn bar(f: Foo) {}

fn main() {
    bar(Foo{
        v:[10, 20] // E308, expected [usize], found [usize; 2]
    });
}

Mentoring instructions can be found in this comment

[vlad20012]

Btw, we should probably use Long instead of Int for array size. Just because if usize is even 32-bit it’s still more than java’s int and our type inference will fail on 3Gb arrays =D

[mkaput]

Unfortunately, now I don’t have a lot of time to grab large task, but I want to help too.

I know that feel bro