Don't CoerceUnsized dyn* to dyn*

1 files changed, 26 insertions, 0 deletions

diff --git a/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs
new file mode 100644
index 00000000000..b4ff8a22286
--- /dev/null
+++ b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs
@@ -0,0 +1,26 @@
+// check-pass
+
+#![feature(dyn_star)]
+#![allow(incomplete_features)]
+
+trait AddOne {
+    fn add1(&mut self) -> usize;
+}
+
+impl AddOne for usize {
+    fn add1(&mut self) -> usize {
+        *self += 1;
+        *self
+    }
+}
+
+fn add_one(i: &mut (dyn* AddOne + '_)) -> usize {
+    i.add1()
+}
+
+fn main() {
+    let mut x = 42usize as dyn* AddOne;
+
+    println!("{}", add_one(&mut x));
+    println!("{}", add_one(&mut x));
+}