stabilize `nonnull_cast` feature

src/liballoc/lib.rs

@@ -99,7 +99,6 @@
 #![feature(lang_items)]
 #![feature(libc)]
 #![feature(needs_allocator)]
-#![feature(nonnull_cast)]
 #![feature(nonzero)]
 #![feature(optin_builtin_traits)]
 #![feature(pattern)]

src/libcore/ptr.rs

@@ -2742,7 +2742,7 @@ impl<T: ?Sized> NonNull<T> {
     }
 
     /// Cast to a pointer of another type
-    #[unstable(feature = "nonnull_cast", issue = "47653")]
+    #[stable(feature = "nonnull_cast", since = "1.27.0")]
     pub fn cast<U>(self) -> NonNull<U> {
         unsafe {
             NonNull::new_unchecked(self.as_ptr() as *mut U)

src/libstd/lib.rs

@@ -275,7 +275,6 @@
 #![feature(macro_reexport)]
 #![feature(macro_vis_matcher)]
 #![feature(needs_panic_runtime)]
-#![feature(nonnull_cast)]
 #![feature(exhaustive_patterns)]
 #![feature(nonzero)]
 #![feature(num_bits_bytes)]

src/test/run-pass/realloc-16687.rs

@@ -13,7 +13,7 @@
 // Ideally this would be revised to use no_std, but for now it serves
 // well enough to reproduce (and illustrate) the bug from #16687.
 
-#![feature(heap_api, allocator_api, nonnull_cast)]
+#![feature(heap_api, allocator_api)]
 
 use std::alloc::{Global, Alloc, Layout};
 use std::ptr::{self, NonNull};