stabilized needs_drop (fixes #41890)

Author: budziq

src/libarena/lib.rs

@@ -28,7 +28,6 @@
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(generic_param_attrs)]
-#![feature(needs_drop)]
 #![cfg_attr(test, feature(test))]
 
 #![allow(deprecated)]

src/libcore/mem.rs

@@ -332,7 +332,6 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
 /// Here's an example of how a collection might make use of needs_drop:
 ///
 /// ```
-/// #![feature(needs_drop)]
 /// use std::{mem, ptr};
 ///
 /// pub struct MyCollection<T> {
@@ -359,7 +358,7 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
 /// }
 /// ```
 #[inline]
-#[unstable(feature = "needs_drop", issue = "41890")]
+#[stable(feature = "needs_drop", since = "1.22.0")]
 pub fn needs_drop<T>() -> bool {
     unsafe { intrinsics::needs_drop::<T>() }
 }

src/libstd/lib.rs

@@ -276,7 +276,6 @@
 #![feature(macro_reexport)]
 #![feature(macro_vis_matcher)]
 #![feature(needs_panic_runtime)]
-#![feature(needs_drop)]
 #![feature(never_type)]
 #![feature(num_bits_bytes)]
 #![feature(old_wrapping)]