Function recursion

tests/all/call_hook.rs:347–412

()

#[test]
fn recursion() -> Result<(), Error> {
    // Make sure call hook behaves reasonably when called recursively

    let engine = Engine::default();
    let mut store = Store::new(&engine, State::default());
    store.call_hook(sync_call_hook);
    let mut linker = Linker::new(&engine);

    linker.func_wrap("host", "f", |mut caller: Caller<State>, n: i32| {
        assert_eq!(caller.data().context.last(), Some(&Context::Host));

        assert_eq!(caller.data().calls_into_host, caller.data().calls_into_wasm);

        // Recurse
        if n > 0 {
            caller
                .get_export("export")
                .expect("caller exports \"export\"")
                .into_func()
                .expect("export is a func")
                .typed::<i32, ()>(&caller)
                .expect("export typing")
                .call(&mut caller, n - 1)
                .unwrap()
        }
    })?;

    let wat = r#"
        (module
            (import "host" "f"
                (func $f (param i32)))
            (func (export "export") (param i32)
                (call $f (local.get 0)))
        )
    "#;
    let module = Module::new(&engine, wat)?;

    let inst = linker.instantiate(&mut store, &module)?;
    let export = inst
        .get_export(&mut store, "export")
        .expect("get export")
        .into_func()
        .expect("export is func");

    // Recursion depth:
    let n: usize = 10;

    export.call(&mut store, &[Val::I32(n as i32)], &mut [])?;

    // Recurse down to 0: n+1 calls
    assert_eq!(store.data().calls_into_host, n + 1);
    assert_eq!(store.data().returns_from_host, n + 1);
    assert_eq!(store.data().calls_into_wasm, n + 1);
    assert_eq!(store.data().returns_from_wasm, n + 1);

    export
        .typed::<i32, ()>(&store)?
        .call(&mut store, n as i32)?;