Rename NonNull::empty to dangling.

Author: SimonSapin

src/libcore/ptr.rs

@@ -2370,6 +2370,7 @@ impl<T: Sized> Unique<T> {
     ///
     /// This is useful for initializing types which lazily allocate, like
     /// `Vec::new` does.
+    // FIXME: rename to dangling() to match NonNull?
     pub fn empty() -> Self {
         unsafe {
             let ptr = mem::align_of::<T>() as *mut T;
@@ -2509,7 +2510,7 @@ impl<T: Sized> NonNull<T> {
     /// This is useful for initializing types which lazily allocate, like
     /// `Vec::new` does.
     #[stable(feature = "nonnull", since = "1.24.0")]
-    pub fn empty() -> Self {
+    pub fn dangling() -> Self {
         unsafe {
             let ptr = mem::align_of::<T>() as *mut T;
             NonNull::new_unchecked(ptr)