How to get host memory from a host function?

[orsinium]

I can define a host function that uses module-defined memory like this:

linker.func_wrap("env", "hline", |mut caller: C, x: i32, y: i32, len: u32| {
    let mem = match caller.get_export("memory") {
        Some(wasmi::Extern::Memory(mem)) => mem,
        _ => panic!("memory not found"),
    };
    let (data, bridge) = mem.data_and_store_mut(&mut caller);
    let frame_buf = FrameBuf::from_memory(data);
    bridge.wasm4_hline(frame_buf, x, y, len)
})?;

However, if I define a memory on the host side:

let mem_type = wasmi::MemoryType::new(1, Some(1)).unwrap();
let mem = wasmi::Memory::new(&mut store, mem_type).unwrap();
linker.define("env", "memory", mem).unwrap();

I can't simply use mem after that because linker.define takes ownership of it. I need to get is somehow back from the store. Outside of the host-defined functions, I can do something like this:

let memory = match linker.get(&mut store, "env", "memory") {
    Some(wasmi::Extern::Memory(memory)) => memory,
    _ => panic!("memory not found"),
};

However, if I try to do the same inside of a linker.func_wrap closure, I get a compilation error:

borrowed data escapes outside of function
`linker` escapes the function body here

Is there a way to get access to the memory inside the linker from a wasmi::Func? I don't see how to keep its ownership after calling linker.define and I don't see any method for that in the wasmi::Caller.

[Robbepop]

Wasm types such as Memory, Table, Global and Func are deliberately Copy and Clone types and thus cheap to clone. This works since they are just fancy, typed indices into some tables into the Store.

Thus you can simply copy the mem before passing it to the Linker in one of your examples and even put mem into the HostState to access it via host functions amongst others.