another test for too big type

tests/compile-fail/too-big-unsized.rs

@@ -0,0 +1,18 @@
+use std::mem;
+
+#[allow(unused)]
+struct MySlice {
+    prefix: u64,
+    tail: [u8],
+}
+
+#[cfg(target_pointer_width = "64")]
+const TOO_BIG: usize = 1usize << 47;
+#[cfg(target_pointer_width = "32")]
+const TOO_BIG: usize = 1usize << 31;
+
+fn main() { unsafe {
+    let ptr = Box::into_raw(Box::new(0u8));
+    // The slice part is actually not "too big", but together with the `prefix` field it is.
+    let _x: &MySlice = mem::transmute((ptr, TOO_BIG-1)); //~ ERROR: invalid reference metadata: total size is bigger than largest supported object
+} }