1 files changed, 30 insertions, 0 deletions
diff --git a/src/test/ui/box/thin_new.rs b/src/test/ui/box/thin_new.rs
new file mode 100644
index 000000000..53f46478b
--- /dev/null
+++ b/src/test/ui/box/thin_new.rs
@@ -0,0 +1,30 @@
+#![feature(thin_box)]
+// run-pass
+use std::boxed::ThinBox;
+use std::error::Error;
+use std::{fmt, mem};
+
+fn main() {
+    let thin_error: ThinBox<dyn Error> = ThinBox::new_unsize(Foo);
+    assert_eq!(mem::size_of::<*const i32>(), mem::size_of_val(&thin_error));
+    println!("{:?}", thin_error);
+
+    let thin = ThinBox::new(42i32);
+    assert_eq!(mem::size_of::<*const i32>(), mem::size_of_val(&thin));
+    println!("{:?}", thin);
+
+    let thin_slice = ThinBox::<[i32]>::new_unsize([1, 2, 3, 4]);
+    assert_eq!(mem::size_of::<*const i32>(), mem::size_of_val(&thin_slice));
+    println!("{:?}", thin_slice);
+}
+
+#[derive(Debug)]
+struct Foo;
+
+impl fmt::Display for Foo {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "boooo!")
+    }
+}
+
+impl Error for Foo {}