drop requires an owned move-only value

Meaning

drop may consume an owned string, list, or struct. Copy-only values and borrowed values do not own a releasable allocation in this operation.

Arrays, integers, floats, booleans, characters, raw pointer scalar values, and fieldless enums use copy behavior under the current source model. A raw pointer address also does not prove ownership of its pointee.

Why it happens

Code may try to imitate manual destruction from another language or may call drop inside a function whose ordinary parameter only borrows.

Invalid code

fn main() -> Int {
    let values = [1, 2, 3]
    drop(values)
    return 0
}

Correct code

struct Box { value: Int }
fn main() -> Int {
    let box = Box { value: 1 }
    drop(box)
    return 0
}

Common fixes

Remove drop for copy-only data, or ensure the function receives ownership with sink before dropping a parameter.

For a foreign resource, use its declared compatible release operation and ownership contract rather than dropping the raw Ptr. Do not change a parameter to sink unless the function should truly consume the caller's value.