Function smoke_test_gc_impl

tests/all/gc.rs:30–86

(use_epochs: bool)

}

fn smoke_test_gc_impl(use_epochs: bool) -> Result<()> {
    let (mut store, module) = ref_types_module(
        use_epochs,
        r#"
            (module
                (import "" "" (func $do_gc))
                (func $recursive (export "func") (param i32 externref) (result externref)
                    local.get 0
                    i32.eqz
                    if (result externref)
                        call $do_gc
                        local.get 1
                    else
                        local.get 0
                        i32.const 1
                        i32.sub
                        local.get 1
                        call $recursive
                    end
                )
            )
        "#,
    )?;

    let do_gc = Func::wrap(&mut store, |mut caller: Caller<'_, _>| {
        // Do a GC with `externref`s on the stack in Wasm frames.
        caller.gc(None)
    });
    let instance = Instance::new(&mut store, &module, &[do_gc.into()])?;
    let func = instance.get_func(&mut store, "func").unwrap();

    let inner_dropped = Arc::new(AtomicBool::new(false));

    {
        let mut scope = RootScope::new(&mut store);

        let r = ExternRef::new(&mut scope, SetFlagOnDrop(inner_dropped.clone()))?;
        {
            let args = [Val::I32(5), Val::ExternRef(Some(r))];
            func.call(&mut scope, &args, &mut [Val::I32(0)])?;
        }

        // Doing a GC should see that there aren't any `externref`s on the stack in
        // Wasm frames anymore.
        scope.as_context_mut().gc(None)?;

        // But the scope should still be rooting `r`.
        assert!(!inner_dropped.load(SeqCst));
    }

    // Exiting the scope and unrooting `r` should have dropped the inner
    // `SetFlagOnDrop` value.
    store.gc(None)?;
    assert!(inner_dropped.load(SeqCst));

    Ok(())
}