Why I need Copy trait here?

[steffahn]

This error message stems from the fact that array initialization of the form [expr; N] requires the type of expr to implement Copy.

See also this website.

In your case, you can just use e.g. control_tx: Default::default().

Another option that has come up in a recent thread (that I’m currently not finding for some reason) is to define some const NO_SENDER: Option<Sender<ControlCommand>> = None; and use [NO_SENDER; 8]. I’m personally feeling like: if constants work, they ought to, eventually, get around to make None work directly as well. Edit2: Nevermind it’s already implemented, just not stabilized. On nightly with #![feature(const_in_array_repeat_expressions)], using None directly works.

Edit - this thread:

How to Initialize an array of Optional Mutable Objects?

Because mutable references are not Copy I get a compiler error when trying to use the array initialization syntax to create a new instance of an array of mutable values. How do I initialize this array with all Nones? #![allow(warnings)] fn main() { let array: [Option<&mut str>; 16] = [None; 16]; } (Playground) Errors: Compiling playground v0.0.1 (/playground) error[E0277]: the trait bound `std::option::Option<&mut str>: std::marker::Copy` is not satisfied --> src/main.rs:4:41 | 4…