Rollup merge of rust-lang#123868 - eduardosm:stabilize-slice_ptr_len, r=jhpratt

Stabilize (const_)slice_ptr_len and (const_)slice_ptr_is_empty_nonnull

Stabilized API:

```rust
impl<T> *mut [T] {
    pub const fn len(self) -> usize;
    pub const fn is_empty(self) -> bool;
}

impl<T> *const [T] {
    pub const fn len(self) -> usize;
    pub const fn is_empty(self) -> bool;
}

impl<T> NonNull<[T]> {
    pub const fn is_empty(self) -> bool;
}
```

FCP completed in tracking issue: rust-lang#71146

Author: jhpratt

library/alloc/src/lib.rs

@@ -151,7 +151,6 @@
 #![feature(slice_from_ptr_range)]
 #![feature(slice_index_methods)]
 #![feature(slice_ptr_get)]
-#![feature(slice_ptr_len)]
 #![feature(slice_range)]
 #![feature(std_internals)]
 #![feature(str_internals)]

library/core/src/lib.rs

@@ -159,7 +159,6 @@
 #![feature(const_slice_from_raw_parts_mut)]
 #![feature(const_slice_from_ref)]
 #![feature(const_slice_index)]
-#![feature(const_slice_ptr_len)]
 #![feature(const_slice_split_at_mut)]
 #![feature(const_str_from_utf8_unchecked_mut)]
 #![feature(const_strict_overflow_ops)]

library/core/src/ptr/const_ptr.rs

@@ -1647,16 +1647,15 @@ impl<T> *const [T] {
     /// # Examples
     ///
     /// ```rust
-    /// #![feature(slice_ptr_len)]
-    ///
     /// use std::ptr;
     ///
     /// let slice: *const [i8] = ptr::slice_from_raw_parts(ptr::null(), 3);
     /// assert_eq!(slice.len(), 3);
     /// ```
     #[inline]
-    #[unstable(feature = "slice_ptr_len", issue = "71146")]
-    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    #[stable(feature = "slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_allow_const_fn_unstable(ptr_metadata)]
     pub const fn len(self) -> usize {
         metadata(self)
     }
@@ -1666,15 +1665,14 @@ impl<T> *const [T] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(slice_ptr_len)]
     /// use std::ptr;
     ///
     /// let slice: *const [i8] = ptr::slice_from_raw_parts(ptr::null(), 3);
     /// assert!(!slice.is_empty());
     /// ```
     #[inline(always)]
-    #[unstable(feature = "slice_ptr_len", issue = "71146")]
-    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    #[stable(feature = "slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
     pub const fn is_empty(self) -> bool {
         self.len() == 0
     }
@@ -1804,7 +1802,7 @@ impl<T, const N: usize> *const [T; N] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(array_ptr_get, slice_ptr_len)]
+    /// #![feature(array_ptr_get)]
     ///
     /// let arr: *const [i32; 3] = &[1, 2, 4] as *const [i32; 3];
     /// let slice: *const [i32] = arr.as_slice();

library/core/src/ptr/mut_ptr.rs

@@ -1909,15 +1909,15 @@ impl<T> *mut [T] {
     /// # Examples
     ///
     /// ```rust
-    /// #![feature(slice_ptr_len)]
     /// use std::ptr;
     ///
     /// let slice: *mut [i8] = ptr::slice_from_raw_parts_mut(ptr::null_mut(), 3);
     /// assert_eq!(slice.len(), 3);
     /// ```
     #[inline(always)]
-    #[unstable(feature = "slice_ptr_len", issue = "71146")]
-    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    #[stable(feature = "slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_allow_const_fn_unstable(ptr_metadata)]
     pub const fn len(self) -> usize {
         metadata(self)
     }
@@ -1927,15 +1927,14 @@ impl<T> *mut [T] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(slice_ptr_len)]
     /// use std::ptr;
     ///
     /// let slice: *mut [i8] = ptr::slice_from_raw_parts_mut(ptr::null_mut(), 3);
     /// assert!(!slice.is_empty());
     /// ```
     #[inline(always)]
-    #[unstable(feature = "slice_ptr_len", issue = "71146")]
-    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    #[stable(feature = "slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_ptr_len", since = "CURRENT_RUSTC_VERSION")]
     pub const fn is_empty(self) -> bool {
         self.len() == 0
     }

library/core/src/ptr/non_null.rs

@@ -1562,7 +1562,6 @@ impl<T> NonNull<[T]> {
     /// ```
     #[stable(feature = "slice_ptr_len_nonnull", since = "1.63.0")]
     #[rustc_const_stable(feature = "const_slice_ptr_len_nonnull", since = "1.63.0")]
-    #[rustc_allow_const_fn_unstable(const_slice_ptr_len)]
     #[must_use]
     #[inline]
     pub const fn len(self) -> usize {
@@ -1574,14 +1573,16 @@ impl<T> NonNull<[T]> {
     /// # Examples
     ///
     /// ```rust
-    /// #![feature(slice_ptr_is_empty_nonnull)]
     /// use std::ptr::NonNull;
     ///
     /// let slice: NonNull<[i8]> = NonNull::slice_from_raw_parts(NonNull::dangling(), 3);
     /// assert!(!slice.is_empty());
     /// ```
-    #[unstable(feature = "slice_ptr_is_empty_nonnull", issue = "71146")]
-    #[rustc_const_unstable(feature = "const_slice_ptr_is_empty_nonnull", issue = "71146")]
+    #[stable(feature = "slice_ptr_is_empty_nonnull", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(
+        feature = "const_slice_ptr_is_empty_nonnull",
+        since = "CURRENT_RUSTC_VERSION"
+    )]
     #[must_use]
     #[inline]
     pub const fn is_empty(self) -> bool {

library/core/tests/lib.rs

@@ -54,7 +54,6 @@
 #![feature(sort_internals)]
 #![feature(slice_take)]
 #![feature(slice_from_ptr_range)]
-#![feature(slice_ptr_len)]
 #![feature(slice_split_once)]
 #![feature(split_as_slice)]
 #![feature(maybe_uninit_fill)]

library/std/src/lib.rs

@@ -265,7 +265,6 @@
     feature(slice_index_methods, coerce_unsized, sgx_platform)
 )]
 #![cfg_attr(any(windows, target_os = "uefi"), feature(round_char_boundary))]
-#![cfg_attr(target_os = "xous", feature(slice_ptr_len))]
 #![cfg_attr(target_family = "wasm", feature(stdarch_wasm_atomic_wait))]
 #![cfg_attr(
     all(any(target_arch = "x86_64", target_arch = "x86"), target_os = "uefi"),

tests/ui/consts/const_fn_unsize.rs

@@ -1,5 +1,4 @@
 //@ run-pass
-#![feature(slice_ptr_len)]
 
 use std::ptr::NonNull;