How Rust Determines If an Array Is Copy Based on Its Element Type

In Rust, whether an array implements the Copy trait depends entirely on whether its element type does. Primitive types like i32 and bool implement Copy, so arrays containing them — such as [i32; 3] — are also Copy, meaning they are duplicated rather than moved when passed to a loop. In contrast, types like String and Vec do not implement Copy, so arrays or collections holding them are moved into the iterator, making the original variable inaccessible afterward. This behaviour is not special compiler logic but is defined in Rust's standard library via a blanket implementation: impl Copy for [T; N] where T: Copy. Understanding this rule helps developers predict ownership and borrowing behaviour when iterating over arrays in Rust.