call the mut version as_mut_ptr and also add an as_ptr-like method to NonNull slices

Author: RalfJung

src/libcore/lib.rs

@@ -93,6 +93,7 @@
 #![feature(const_slice_ptr_len)]
 #![feature(const_type_name)]
 #![feature(const_likely)]
+#![feature(const_slice_ptr_ptr)]
 #![feature(custom_inner_attributes)]
 #![feature(decl_macro)]
 #![feature(doc_cfg)]

src/libcore/ptr/mut_ptr.rs

@@ -1041,12 +1041,12 @@ impl<T> *mut [T] {
     /// use std::ptr;
     ///
     /// let slice: *mut [i8] = ptr::slice_from_raw_parts_mut(ptr::null_mut(), 3);
-    /// assert_eq!(slice.as_ptr(), 0 as *mut i8);
+    /// assert_eq!(slice.as_mut_ptr(), 0 as *mut i8);
     /// ```
     #[inline]
     #[unstable(feature = "slice_ptr_ptr", issue = "none")]
     #[rustc_const_unstable(feature = "const_slice_ptr_ptr", issue = "none")]
-    pub const fn as_ptr(self) -> *mut T {
+    pub const fn as_mut_ptr(self) -> *mut T {
         self as *mut T
     }
 }

src/libcore/ptr/non_null.rs

@@ -204,6 +204,26 @@ impl<T> NonNull<[T]> {
     pub const fn len(self) -> usize {
         self.as_ptr().len()
     }
+
+    /// Returns a non-null pointer to the slice's buffer.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// #![feature(slice_ptr_ptr, nonnull_slice_from_raw_parts)]
+    ///
+    /// use std::ptr::NonNull;
+    ///
+    /// let slice: NonNull<[i8]> = NonNull::slice_from_raw_parts(NonNull::dangling(), 3);
+    /// assert_eq!(slice.as_non_null_ptr(), NonNull::new(1 as *mut i8).unwrap());
+    /// ```
+    #[inline]
+    #[unstable(feature = "slice_ptr_ptr", issue = "none")]
+    #[rustc_const_unstable(feature = "const_slice_ptr_ptr", issue = "none")]
+    pub const fn as_non_null_ptr(self) -> NonNull<T> {
+        // SAFETY: We know `self` is non-null.
+        unsafe { NonNull::new_unchecked(self.as_ptr().as_mut_ptr()) }
+    }
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]