Add tests

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/ui/impl-trait/trait_upcasting.rs b/tests/ui/impl-trait/trait_upcasting.rs
new file mode 100644
index 00000000000..cb3c17e87b4
--- /dev/null
+++ b/tests/ui/impl-trait/trait_upcasting.rs
@@ -0,0 +1,26 @@
+//! Test that we allow unsizing `Trait<Concrete>` to `Trait<Opaque>` and vice versa
+
+trait Trait<T> {}
+
+impl<T, U> Trait<T> for U {}
+
+fn hello() -> &'static (dyn Trait<impl Sized> + Send) {
+    if false {
+        let x = hello();
+        let _: &'static dyn Trait<()> = x;
+        //~^ ERROR: mismatched types
+    }
+    todo!()
+}
+
+fn bye() -> &'static dyn Trait<impl Sized> {
+    if false {
+        let mut x = bye();
+        let y: &'static (dyn Trait<()> + Send) = &();
+        x = y;
+        //~^ ERROR: mismatched types
+    }
+    todo!()
+}
+
+fn main() {}