Auto merge of #46952 - SimonSapin:nonnull, r=alexcrichton

Rename std::ptr::Shared to NonNull and stabilize it

This implements the changes proposed at https://github.com/rust-lang/rust/issues/27730#issuecomment-352800629:

> * Rename `Shared<T>` to `NonNull<T>` and stabilize it. (Being in the `ptr` module is enough to say that it’s a pointer. I’m not very attached to this specific name though.)
> * Rename `Box<T>` methods ~~`from_unique`~~/`into_unique` to ~~`from_nonnull`~~/`into_nonnull` (or whatever names are deemed appropriate), replace `Unique<T>` with `NonNull<T>` in their signatures, and stabilize them.
> *  Replace `Unique<T>` with `NonNull<T>` in the signatures of methods of the `Alloc` trait.
> * Mark `Unique` “permanently-unstable” by replacing remaining occurrences of `#[unstable(feature = "unique", issue = "27730")]` with:
>
>   ```rust
>   #[unstable(feature = "ptr_internals", issue = "0", reason = "\
>       use NonNull instead and consider PhantomData<T> (if you also use #[may_dangle]), \
>       Send, and/or Sync")]
>   ```
>
>   (Maybe the `reason` string is only useful on the struct definition.) Ideally it would be made private to some crate instead, but it needs to be used in both liballoc and libstd.
> * (Leave `NonZero` and `Zeroable` unstable for now, and subject to future bikeshedding.)

1 files changed, 10 insertions, 10 deletions

diff --git a/src/liballoc/allocator.rs b/src/liballoc/allocator.rs
index c2a8f5f8ff9..55e8c0b430f 100644
--- a/src/liballoc/allocator.rs
+++ b/src/liballoc/allocator.rs
@@ -19,7 +19,7 @@ use core::cmp;
 use core::fmt;
 use core::mem;
 use core::usize;
-use core::ptr::{self, Unique};
+use core::ptr::{self, NonNull};
 
 /// Represents the combination of a starting address and
 /// a total capacity of the returned block.
@@ -895,12 +895,12 @@ pub unsafe trait Alloc {
     /// Clients wishing to abort computation in response to an
     /// allocation error are encouraged to call the allocator's `oom`
     /// method, rather than directly invoking `panic!` or similar.
-    fn alloc_one<T>(&mut self) -> Result<Unique<T>, AllocErr>
+    fn alloc_one<T>(&mut self) -> Result<NonNull<T>, AllocErr>
         where Self: Sized
     {
         let k = Layout::new::<T>();
         if k.size() > 0 {
-            unsafe { self.alloc(k).map(|p| Unique::new_unchecked(p as *mut T)) }
+            unsafe { self.alloc(k).map(|p| NonNull::new_unchecked(p as *mut T)) }
         } else {
             Err(AllocErr::invalid_input("zero-sized type invalid for alloc_one"))
         }
@@ -923,7 +923,7 @@ pub unsafe trait Alloc {
     /// * `ptr` must denote a block of memory currently allocated via this allocator
     ///
     /// * the layout of `T` must *fit* that block of memory.
-    unsafe fn dealloc_one<T>(&mut self, ptr: Unique<T>)
+    unsafe fn dealloc_one<T>(&mut self, ptr: NonNull<T>)
         where Self: Sized
     {
         let raw_ptr = ptr.as_ptr() as *mut u8;
@@ -963,7 +963,7 @@ pub unsafe trait Alloc {
     /// Clients wishing to abort computation in response to an
     /// allocation error are encouraged to call the allocator's `oom`
     /// method, rather than directly invoking `panic!` or similar.
-    fn alloc_array<T>(&mut self, n: usize) -> Result<Unique<T>, AllocErr>
+    fn alloc_array<T>(&mut self, n: usize) -> Result<NonNull<T>, AllocErr>
         where Self: Sized
     {
         match Layout::array::<T>(n) {
@@ -971,7 +971,7 @@ pub unsafe trait Alloc {
                 unsafe {
                     self.alloc(layout.clone())
                         .map(|p| {
-                            Unique::new_unchecked(p as *mut T)
+                            NonNull::new_unchecked(p as *mut T)
                         })
                 }
             }
@@ -1012,15 +1012,15 @@ pub unsafe trait Alloc {
     /// reallocation error are encouraged to call the allocator's `oom`
     /// method, rather than directly invoking `panic!` or similar.
     unsafe fn realloc_array<T>(&mut self,
-                               ptr: Unique<T>,
+                               ptr: NonNull<T>,
                                n_old: usize,
-                               n_new: usize) -> Result<Unique<T>, AllocErr>
+                               n_new: usize) -> Result<NonNull<T>, AllocErr>
         where Self: Sized
     {
         match (Layout::array::<T>(n_old), Layout::array::<T>(n_new), ptr.as_ptr()) {
             (Some(ref k_old), Some(ref k_new), ptr) if k_old.size() > 0 && k_new.size() > 0 => {
                 self.realloc(ptr as *mut u8, k_old.clone(), k_new.clone())
-                    .map(|p|Unique::new_unchecked(p as *mut T))
+                    .map(|p| NonNull::new_unchecked(p as *mut T))
             }
             _ => {
                 Err(AllocErr::invalid_input("invalid layout for realloc_array"))
@@ -1048,7 +1048,7 @@ pub unsafe trait Alloc {
     /// constraints.
     ///
     /// Always returns `Err` on arithmetic overflow.
-    unsafe fn dealloc_array<T>(&mut self, ptr: Unique<T>, n: usize) -> Result<(), AllocErr>
+    unsafe fn dealloc_array<T>(&mut self, ptr: NonNull<T>, n: usize) -> Result<(), AllocErr>
         where Self: Sized
     {
         let raw_ptr = ptr.as_ptr() as *mut u8;