Cannot derive Trace for a Copy object. #87

It seems that if I try to derive both Copy and Trace in a simple structure, I get this error:

The Copy trait was implemented on a type with a Drop implementation.

Erroneous code example:

#[derive(Copy)]
struct Foo; // error!

impl Drop for Foo {
    fn drop(&mut self) {
    }
}

Explicitly implementing both Drop and Copy trait on a type is currently
disallowed. This feature can make some sense in theory, but the current
implementation is incorrect and can lead to memory unsafety (see
issue #20126), so it has been disabled for now.

But from my understanding, a simple Copy structure such as:

#[derive(Debug, Clone, Copy, Trace)]
struct Sym(usize);

should be easy to implement, and the Trace implementation could be empty, right? Is there a proper way to do this? It's currently blocking doing type-safe string interning in Boa.