1 files changed, 35 insertions, 0 deletions
diff --git a/third_party/rust/fallible_collections/src/rc.rs b/third_party/rust/fallible_collections/src/rc.rs
new file mode 100644
index 0000000000..4fc16dc2af
--- /dev/null
+++ b/third_party/rust/fallible_collections/src/rc.rs
@@ -0,0 +1,35 @@
+//! Implement a Fallible Rc
+use super::FallibleBox;
+use crate::TryReserveError;
+use alloc::boxed::Box;
+use alloc::rc::Rc;
+/// trait to implement Fallible Rc
+pub trait FallibleRc<T> {
+    /// try creating a new Rc, returning a Result<Box<T>,
+    /// TryReserveError> if allocation failed
+    fn try_new(t: T) -> Result<Self, TryReserveError>
+    where
+        Self: Sized;
+}
+
+impl<T> FallibleRc<T> for Rc<T> {
+    fn try_new(t: T) -> Result<Self, TryReserveError> {
+        let b = <Box<T> as FallibleBox<T>>::try_new(t)?;
+        Ok(Rc::from(b))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn fallible_rc() {
+        use std::rc::Rc;
+
+        let mut x = Rc::new(3);
+        *Rc::get_mut(&mut x).unwrap() = 4;
+        assert_eq!(*x, 4);
+
+        let _y = Rc::clone(&x);
+        assert!(Rc::get_mut(&mut x).is_none());
+    }
+}