How to go from android_activity::AndroidApp to ndk::NativeActivity?

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1

I created an Android app that uses NativeActivity. It starts up and as desired, calls my android_main(app: AndroidApp) function that I defined in Rust. Here are the docs for android_activity::AndroidApp.

There is another type, in the ndk crate, called NativeActivity. It has a method I'd like to call, internal_data_path(). But I can't figure out how to go from that AndroidApp to a NativeActivity.

I tried writing the code below, but I'm pretty sure that pointer cast there is bad. Because once I try to call internal_data_path() on that NativeActivity, the app crashes.

// Set this when app starts up.
static mut ANDROID_APP: Option<AndroidApp> = None;

pub fn native_activity() -> NativeActivity {
    unsafe {
        let app = ANDROID_APP.as_ref().unwrap();        
        let ptr = NonNull::new(app.activity_as_ptr() as *mut _).unwrap();
        NativeActivity::from_ptr(ptr)
    }
}
...
#[no_mangle]
fn android_main(app: AndroidApp) {
    unsafe { ANDROID_APP = Some(app.clone()); }
    ...

Docs for AndroidApp::activity_as_ptr().