Backport official GLib iterator safety fix for Linux desktop

apps/desktop/src-tauri/vendor/glib/src/clone.rs

@@ -0,0 +1,101 @@
+// Take a look at the license at the top of the repository in the LICENSE file.
+
+use std::{
+    marker::PhantomData,
+    rc::{self, Rc},
+    sync::{self, Arc},
+};
+
+// rustdoc-stripper-ignore-next
+/// Trait for generalizing downgrading a strong reference to a weak reference.
+pub trait Downgrade
+where
+    Self: Sized,
+{
+    // rustdoc-stripper-ignore-next
+    /// Weak reference type.
+    type Weak;
+
+    // rustdoc-stripper-ignore-next
+    /// Downgrade to a weak reference.
+    fn downgrade(&self) -> Self::Weak;
+}
+
+// rustdoc-stripper-ignore-next
+/// Trait for generalizing upgrading a weak reference to a strong reference.
+pub trait Upgrade
+where
+    Self: Sized,
+{
+    // rustdoc-stripper-ignore-next
+    /// Strong reference type.
+    type Strong;
+
+    // rustdoc-stripper-ignore-next
+    /// Try upgrading a weak reference to a strong reference.
+    fn upgrade(&self) -> Option<Self::Strong>;
+}
+
+impl<T: Downgrade + crate::ObjectType> Upgrade for crate::WeakRef<T> {
+    type Strong = T;
+
+    fn upgrade(&self) -> Option<Self::Strong> {
+        self.upgrade()
+    }
+}
+
+impl<T> Downgrade for PhantomData<T> {
+    type Weak = PhantomData<T>;
+
+    fn downgrade(&self) -> Self::Weak {
+        PhantomData
+    }
+}
+
+impl<T: Downgrade> Downgrade for &T {
+    type Weak = T::Weak;
+
+    fn downgrade(&self) -> Self::Weak {
+        T::downgrade(*self)
+    }
+}
+
+impl<T> Downgrade for Arc<T> {
+    type Weak = sync::Weak<T>;
+
+    fn downgrade(&self) -> Self::Weak {
+        Arc::downgrade(self)
+    }
+}
+
+impl<T> Upgrade for PhantomData<T> {
+    type Strong = PhantomData<T>;
+
+    fn upgrade(&self) -> Option<Self::Strong> {
+        Some(PhantomData)
+    }
+}
+
+impl<T> Upgrade for sync::Weak<T> {
+    type Strong = Arc<T>;
+
+    fn upgrade(&self) -> Option<Self::Strong> {
+        self.upgrade()
+    }
+}
+
+impl<T> Downgrade for Rc<T> {
+    type Weak = rc::Weak<T>;
+
+    fn downgrade(&self) -> Self::Weak {
+        Rc::downgrade(self)
+    }
+}
+
+impl<T> Upgrade for rc::Weak<T> {
+    type Strong = Rc<T>;
+
+    fn upgrade(&self) -> Option<Self::Strong> {
+        self.upgrade()
+    }
+}