#[lang_item] for core::ptr::Unique

library/core/src/ptr/unique.rs

@@ -32,6 +32,8 @@ use crate::ptr::NonNull;
 )]
 #[doc(hidden)]
 #[repr(transparent)]
+// Lang item used experimentally by Miri to define the semantics of `Unique`.
+#[cfg_attr(not(bootstrap), lang = "ptr_unique")]
 pub struct Unique<T: ?Sized> {
     pointer: NonNull<T>,
     // NOTE: this marker has no consequences for variance, but is necessary