Memory leaks when Rust's async function called from Swift

[b01o]

Apple's profiling tool Instruments is reporting memory leaks on each async call from Swift to Rust.

I've tried investigating this but couldn't find the cause. Could anyone help take a look?

Minimal example:

// rust side
#[uniffi::export]
async fn rust_side_function() -> u32 { 42 }

// swift side
Task {
    _ = await rustSideFunction()
}

Observed Behavior

Each call to rustSideFunction() leaks 64 + 64 + 128 bytes (256 bytes total) on my machine (M4 Mac).

I've created this repository to demonstrate the example.