1 files changed, 14 insertions, 0 deletions
diff --git a/tests/ui/box/into-boxed-slice-fail.rs b/tests/ui/box/into-boxed-slice-fail.rs
new file mode 100644
index 00000000000..49dbb170f8e
--- /dev/null
+++ b/tests/ui/box/into-boxed-slice-fail.rs
@@ -0,0 +1,14 @@
+#![feature(box_into_boxed_slice)]
+
+use std::boxed::Box;
+use std::fmt::Debug;
+fn main() {
+    let boxed_slice = Box::new([1,2,3]) as Box<[u8]>;
+    let _ = Box::into_boxed_slice(boxed_slice);
+    //~^ ERROR the size for values of type `[u8]` cannot be known at compilation time
+    //~^^ ERROR the size for values of type `[u8]` cannot be known at compilation time
+    let boxed_trait: Box<dyn Debug> = Box::new(5u8);
+    let _ = Box::into_boxed_slice(boxed_trait);
+    //~^ ERROR the size for values of type `dyn Debug` cannot be known at compilation time
+    //~^^ ERROR the size for values of type `dyn Debug` cannot be known at compilation time
+}