1 files changed, 20 insertions, 0 deletions

diff --git a/src/test/ui/issues/issue-36278-prefix-nesting.rs b/src/test/ui/issues/issue-36278-prefix-nesting.rs
new file mode 100644
index 000000000..a809f7f13
--- /dev/null
+++ b/src/test/ui/issues/issue-36278-prefix-nesting.rs
@@ -0,0 +1,20 @@
+// run-pass
+// Issue 36278: On an unsized struct with >1 level of nontrivial
+// nesting, ensure we are computing dynamic size of prefix correctly.
+
+use std::mem;
+
+const SZ: usize = 100;
+#[allow(unused_tuple_struct_fields)]
+struct P<T: ?Sized>([u8; SZ], T);
+
+type Ack<T> = P<P<T>>;
+
+fn main() {
+    let size_of_sized; let size_of_unsized;
+    let x: Box<Ack<[u8; 0]>> = Box::new(P([0; SZ], P([0; SZ], [0; 0])));
+    size_of_sized = mem::size_of_val::<Ack<_>>(&x);
+    let y: Box<Ack<[u8   ]>> = x;
+    size_of_unsized = mem::size_of_val::<Ack<_>>(&y);
+    assert_eq!(size_of_sized, size_of_unsized);
+}