NSPanel deallocated on .close even with setReleasedWhenClosed(false)

[Elawphant]

Description:
In Rust using objc2, dropping a Retained deallocates the panel even when setReleasedWhenClosed(false) (the default). According to Apple docs, the panel should remain retained by AppKit unless setReleasedWhenClosed(true) is set. This behavior differs from Objective-C/Swift expectations and is relevant for memory management in Rust. Also setting it to true, crashes the app on closing the window.

Minimal Repro Example:

use std::sync::{Arc, RwLock};
use objc2::{define_class, rc::Retained, MainThreadMarker};
use objc2_app_kit::NSPanel;

define_class!(
    #[unsafe(super = NSPanel)]
    #[thread_kind = MainThreadOnly]
    #[derive(Debug)]
    pub struct TestPanel;

    impl TestPanel {
        #[unsafe(method(close))]
        fn close(&self) {
            println!("Panel closed");
            unsafe { let _: () = objc2::msg_send![super(self), close]; }
        }
    }
);

impl TestPanel {
    pub fn new() -> Retained<Self> {
        let mtm = MainThreadMarker::new().unwrap();
        let panel = Self::alloc(mtm).set_ivars(());
        unsafe { objc2::msg_send![super(panel), init] }
    }
}

impl Drop for TestPanel {
    fn drop(&mut self) {
        println!("Panel dropped");
    }
}

fn main() {
    let panel = TestPanel::new();
    panel.close(); // Prints "Panel closed (windowWillClose), Prints "Panel dropped" even without setReleasedWhenClosed(true)
}

Observed Behavior:

• "Panel closed" prints.
• "Panel dropped" prints immediately after dropping the Rust Retained.
• Panel is deallocated even though setReleasedWhenClosed(false) was never set, checked with NSZombieEnabled = "YES"

Expected Behavior (according to Apple docs):

• The panel should remain in memory until setReleasedWhenClosed(true) is called. see Apple Docs 1, Apple Docs 2

Environment:

• macOS 15.6.1
• objc2-app-kit version 0.3.1

Notes:

• This behavior appears safe, but differs from the ObjC documentation.
• Useful for clarifying Rust + objc2 memory semantics.

[madsmtm]

Hmm, I'm on macOS 15.6.1, and I can't seem to reproduce using the following?

#!/usr/bin/env cargo +nightly -Zscript
---
[dependencies]
objc2 = "0.6.2"
objc2-foundation = "0.3.1"
objc2-app-kit = "0.3.1"
---
use objc2::{define_class, rc::Retained, MainThreadMarker, MainThreadOnly};
use objc2_app_kit::NSPanel;

define_class!(
    #[unsafe(super = NSPanel)]
    #[thread_kind = MainThreadOnly]
    #[derive(Debug)]
    pub struct TestPanel;

    impl TestPanel {
        #[unsafe(method(close))]
        fn __close(&self) {
            println!("Panel closed");
            unsafe { let _: () = objc2::msg_send![super(self), close]; }
        }
    }
);

impl TestPanel {
    pub fn new() -> Retained<Self> {
        let mtm = MainThreadMarker::new().unwrap();
        let panel = Self::alloc(mtm).set_ivars(());
        unsafe { objc2::msg_send![super(panel), init] }
    }
}

impl Drop for TestPanel {
    fn drop(&mut self) {
        println!("Panel dropped");
    }
}

fn main() {
    objc2::rc::autoreleasepool(|_| {
        let panel = objc2::rc::autoreleasepool(|_| { TestPanel::new() });
        panel.close(); // Prints "Panel closed"
        println!("end of pool");
    }); // Prints "Panel dropped"
    println!("end");
}