1 files changed, 13 insertions, 0 deletions
diff --git a/src/test/ui/cross/cross-borrow-trait.rs b/src/test/ui/cross/cross-borrow-trait.rs
new file mode 100644
index 000000000..180a75e3d
--- /dev/null
+++ b/src/test/ui/cross/cross-borrow-trait.rs
@@ -0,0 +1,13 @@
+// Test that cross-borrowing (implicitly converting from `Box<T>` to `&T`) is
+// forbidden when `T` is a trait.
+
+struct Foo;
+trait Trait { fn foo(&self) {} }
+impl Trait for Foo {}
+
+pub fn main() {
+    let x: Box<dyn Trait> = Box::new(Foo);
+    let _y: &dyn Trait = x; //~ ERROR E0308
+                            //~| expected reference `&dyn Trait`
+                            //~| found struct `Box<dyn Trait>`
+}