Don't expose macOS implementation details in the public API

The `show_context_menu_for_nsview` method previously used the
`objc::runtime::Object` type, which means that the library's dependence
on `objc` is exposed as part of the public API.

Additionally, since the method is taking a raw pointer (and as such
would be unsound if passing e.g. `ptr::dangling()`), I took the
opportunity to also mark the method as `unsafe`.

This is done in preparation for transitioning to `objc2`.

.changes/make-macos-impl-details-private.md

@@ -0,0 +1,5 @@
+---
+"muda": minor
+---
+
+**Breaking Change** Changed the type of the pointer passed in `show_context_menu_for_nsview` to `c_void`, and make the method `unsafe`.

README.md

@@ -85,7 +85,7 @@ menu.show_context_menu_for_hwnd(window.hwnd() as isize, Some(position.into()));
 #[cfg(target_os = "linux")]
 menu.show_context_menu_for_gtk_window(&gtk_window, Some(position.into()));
 #[cfg(target_os = "macos")]
-menu.show_context_menu_for_nsview(nsview, Some(position.into()));
+unsafe { menu.show_context_menu_for_nsview(nsview, Some(position.into())) };
 ```
 
 ## Processing menu events

examples/tao.rs

@@ -225,7 +225,9 @@ fn show_context_menu(window: &Window, menu: &dyn ContextMenu, position: Option<P
     #[cfg(target_os = "linux")]
     menu.show_context_menu_for_gtk_window(window.gtk_window().as_ref(), position);
     #[cfg(target_os = "macos")]
-    menu.show_context_menu_for_nsview(window.ns_view() as _, position);
+    unsafe {
+        menu.show_context_menu_for_nsview(window.ns_view() as _, position);
+    }
 }
 
 fn load_icon(path: &std::path::Path) -> muda::Icon {

examples/windows-common-controls-v6/src/main.rs

@@ -213,7 +213,7 @@ fn show_context_menu(window: &Window, menu: &dyn ContextMenu, position: Option<P
     {
         use tao::rwh_06::*;
         if let RawWindowHandle::AppKit(handle) = window.window_handle().unwrap().as_raw() {
-            menu.show_context_menu_for_nsview(handle.ns_view.as_ptr() as _, position);
+            unsafe { menu.show_context_menu_for_nsview(handle.ns_view.as_ptr() as _, position) };
         }
     }
 }

examples/winit.rs

@@ -213,7 +213,7 @@ fn show_context_menu(window: &Window, menu: &dyn ContextMenu, position: Option<P
     {
         use winit::raw_window_handle::*;
         if let RawWindowHandle::AppKit(handle) = window.window_handle().unwrap().as_raw() {
-            menu.show_context_menu_for_nsview(handle.ns_view.as_ptr() as _, position);
+            unsafe { menu.show_context_menu_for_nsview(handle.ns_view.as_ptr() as _, position) };
         }
     }
 }

examples/wry.rs

@@ -310,7 +310,9 @@ fn show_context_menu(window: &Window, menu: &dyn ContextMenu, position: Option<P
     #[cfg(target_os = "linux")]
     menu.show_context_menu_for_gtk_window(window.gtk_window().as_ref(), position);
     #[cfg(target_os = "macos")]
-    menu.show_context_menu_for_nsview(window.ns_view() as _, position);
+    unsafe {
+        menu.show_context_menu_for_nsview(window.ns_view() as _, position);
+    }
 }
 
 fn load_icon(path: &std::path::Path) -> muda::Icon {

src/items/submenu.rs

@@ -246,10 +246,16 @@ impl ContextMenu for Submenu {
     }
 
     #[cfg(target_os = "macos")]
-    fn show_context_menu_for_nsview(&self, view: cocoa::base::id, position: Option<Position>) {
-        self.inner
-            .borrow_mut()
-            .show_context_menu_for_nsview(view, position)
+    unsafe fn show_context_menu_for_nsview(
+        &self,
+        view: *const std::ffi::c_void,
+        position: Option<Position>,
+    ) {
+        unsafe {
+            self.inner
+                .borrow_mut()
+                .show_context_menu_for_nsview(view, position)
+        }
     }
 
     #[cfg(target_os = "macos")]

src/lib.rs

@@ -98,15 +98,15 @@
 //! # #[cfg(target_os = "linux")]
 //! # let gtk_window = gtk::Window::builder().build();
 //! # #[cfg(target_os = "macos")]
-//! # let nsview = 0 as *mut objc::runtime::Object;
+//! # let nsview = std::ptr::null();
 //! // --snip--
 //! let position = muda::dpi::PhysicalPosition { x: 100., y: 120. };
 //! #[cfg(target_os = "windows")]
 //! menu.show_context_menu_for_hwnd(window_hwnd, Some(position.into()));
 //! #[cfg(target_os = "linux")]
 //! menu.show_context_menu_for_gtk_window(&gtk_window, Some(position.into()));
 //! #[cfg(target_os = "macos")]
-//! menu.show_context_menu_for_nsview(nsview, Some(position.into()));
+//! unsafe { menu.show_context_menu_for_nsview(nsview, Some(position.into())) };
 //! ```
 //! # Processing menu events
 //!
@@ -336,10 +336,21 @@ pub trait ContextMenu {
     /// Shows this menu as a context menu for the specified `NSView`.
     ///
     /// - `position` is relative to the window top-left corner, if `None`, the cursor position is used.
+    ///
+    /// # Safety
+    ///
+    /// The view must be a pointer to a valid `NSView`.
     #[cfg(target_os = "macos")]
-    fn show_context_menu_for_nsview(&self, view: cocoa::base::id, position: Option<dpi::Position>);
+    unsafe fn show_context_menu_for_nsview(
+        &self,
+        view: *const std::ffi::c_void,
+        position: Option<dpi::Position>,
+    );
 
     /// Get the underlying NSMenu reserved for context menus.
+    ///
+    /// The returned pointer is valid for as long as the `ContextMenu` is. If
+    /// you need it to be alive for longer, retain it.
     #[cfg(target_os = "macos")]
     fn ns_menu(&self) -> *mut std::ffi::c_void;
 }

src/menu.rs

@@ -370,10 +370,17 @@ impl ContextMenu for Menu {
     }
 
     #[cfg(target_os = "macos")]
-    fn show_context_menu_for_nsview(&self, view: cocoa::base::id, position: Option<Position>) {
-        self.inner
-            .borrow_mut()
-            .show_context_menu_for_nsview(view, position)
+    unsafe fn show_context_menu_for_nsview(
+        &self,
+        view: *const std::ffi::c_void,
+        position: Option<Position>,
+    ) {
+        // SAFETY: Upheld by caller
+        unsafe {
+            self.inner
+                .borrow_mut()
+                .show_context_menu_for_nsview(view, position)
+        }
     }
 
     #[cfg(target_os = "macos")]

src/platform_impl/macos/mod.rs

@@ -8,7 +8,7 @@ mod util;
 
 pub(crate) use icon::PlatformIcon;
 
-use std::{cell::RefCell, collections::HashMap, rc::Rc, sync::Once};
+use std::{cell::RefCell, collections::HashMap, ffi::c_void, rc::Rc, sync::Once};
 
 use cocoa::{
     appkit::{self, CGFloat, NSApp, NSApplication, NSEventModifierFlags, NSMenu, NSMenuItem},
@@ -179,8 +179,13 @@ impl Menu {
         unsafe { NSApp().setMainMenu_(NSMenu::new(nil) as _) }
     }
 
-    pub fn show_context_menu_for_nsview(&self, view: id, position: Option<Position>) {
-        show_context_menu(self.ns_menu.1, view, position)
+    pub unsafe fn show_context_menu_for_nsview(
+        &self,
+        view: *const c_void,
+        position: Option<Position>,
+    ) {
+        // SAFETY: Upheld by caller
+        unsafe { show_context_menu(self.ns_menu.1, view, position) }
     }
 
     pub fn ns_menu(&self) -> *mut std::ffi::c_void {
@@ -655,8 +660,13 @@ impl MenuChild {
             .collect()
     }
 
-    pub fn show_context_menu_for_nsview(&self, view: id, position: Option<Position>) {
-        show_context_menu(self.ns_menu.as_ref().unwrap().1, view, position)
+    pub unsafe fn show_context_menu_for_nsview(
+        &self,
+        view: *const c_void,
+        position: Option<Position>,
+    ) {
+        // SAFETY: Upheld by caller
+        unsafe { show_context_menu(self.ns_menu.as_ref().unwrap().1, view, position) }
     }
 
     pub fn set_as_windows_menu_for_nsapp(&self) {
@@ -1066,8 +1076,9 @@ fn menuitem_set_native_icon(menuitem: id, icon: Option<NativeIcon>) {
     }
 }
 
-fn show_context_menu(ns_menu: id, view: id, position: Option<Position>) {
+unsafe fn show_context_menu(ns_menu: id, view: *const c_void, position: Option<Position>) {
     unsafe {
+        let view = view as id;
         let window: id = msg_send![view, window];
         let scale_factor: CGFloat = msg_send![window, backingScaleFactor];
         let (location, in_view) = if let Some(pos) = position.map(|p| p.to_logical(scale_factor)) {