Use MainThreadBound instead of StaticMainThreadBound hack

MainThreadBound::new and MainThreadMarker::new_unchecked are now
available in `const`.

src/platform_impl/apple/appkit/app_state.rs

@@ -5,6 +5,7 @@ use std::sync::atomic::Ordering as AtomicOrdering;
 use std::sync::Arc;
 use std::time::Instant;
 
+use dispatch2::MainThreadBound;
 use objc2::MainThreadMarker;
 use objc2_app_kit::{NSApplication, NSApplicationActivationPolicy, NSRunningApplication};
 use objc2_foundation::NSNotification;
@@ -46,22 +47,10 @@ pub(super) struct AppState {
     // as such should be careful to not add fields that, in turn, strongly reference those.
 }
 
-// TODO(madsmtm): Use `MainThreadBound` once that is possible in `static`s.
-struct StaticMainThreadBound<T>(T);
-
-impl<T> StaticMainThreadBound<T> {
-    const fn get(&self, _mtm: MainThreadMarker) -> &T {
-        &self.0
-    }
-}
-
-unsafe impl<T> Send for StaticMainThreadBound<T> {}
-unsafe impl<T> Sync for StaticMainThreadBound<T> {}
-
-// SAFETY: Creating `StaticMainThreadBound` in a `const` context, where there is no concept of the
+// SAFETY: Creating `MainThreadBound` in a `const` context, where there is no concept of the
 // main thread.
-static GLOBAL: StaticMainThreadBound<OnceCell<Rc<AppState>>> =
-    StaticMainThreadBound(OnceCell::new());
+static GLOBAL: MainThreadBound<OnceCell<Rc<AppState>>> =
+    MainThreadBound::new(OnceCell::new(), unsafe { MainThreadMarker::new_unchecked() });
 
 impl AppState {
     pub(super) fn setup_global(

src/platform_impl/apple/uikit/app_state.rs

@@ -8,6 +8,7 @@ use std::sync::{Arc, Mutex};
 use std::time::Instant;
 use std::{mem, ptr};
 
+use dispatch2::MainThreadBound;
 use objc2::rc::Retained;
 use objc2::MainThreadMarker;
 use objc2_core_foundation::{
@@ -43,22 +44,10 @@ macro_rules! bug_assert {
 /// This is stored separately from AppState, since AppState needs to be accessible while the handler
 /// is executing.
 fn get_handler(mtm: MainThreadMarker) -> &'static EventHandler {
-    // TODO(madsmtm): Use `MainThreadBound` once that is possible in `static`s.
-    struct StaticMainThreadBound<T>(T);
-
-    impl<T> StaticMainThreadBound<T> {
-        const fn get(&self, _mtm: MainThreadMarker) -> &T {
-            &self.0
-        }
-    }
-
-    unsafe impl<T> Send for StaticMainThreadBound<T> {}
-    unsafe impl<T> Sync for StaticMainThreadBound<T> {}
-
     // SAFETY: Creating `StaticMainThreadBound` in a `const` context, where there is no concept
     // of the main thread.
-    static GLOBAL: StaticMainThreadBound<OnceCell<EventHandler>> =
-        StaticMainThreadBound(OnceCell::new());
+    static GLOBAL: MainThreadBound<OnceCell<EventHandler>> =
+        MainThreadBound::new(OnceCell::new(), unsafe { MainThreadMarker::new_unchecked() });
 
     GLOBAL.get(mtm).get_or_init(EventHandler::new)
 }