Rollup merge of rust-lang#71589 - RalfJung:unique-no-shr, r=SimonSapin

remove Unique::from for shared pointer types

r? @SimonSapin

Author: Dylan-DPC

src/liballoc/collections/btree/node.rs

@@ -131,7 +131,7 @@ impl<K, V> BoxedNode<K, V> {
     }
 
     unsafe fn from_ptr(ptr: NonNull<LeafNode<K, V>>) -> Self {
-        BoxedNode { ptr: Unique::from(ptr) }
+        BoxedNode { ptr: Unique::new_unchecked(ptr.as_ptr()) }
     }
 
     fn as_ptr(&self) -> NonNull<LeafNode<K, V>> {

src/liballoc/raw_vec.rs

@@ -151,7 +151,7 @@ impl<T, A: AllocRef> RawVec<T, A> {
 
             let memory = alloc.alloc(layout, init).unwrap_or_else(|_| handle_alloc_error(layout));
             Self {
-                ptr: memory.ptr.cast().into(),
+                ptr: unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) },
                 cap: Self::capacity_from_bytes(memory.size),
                 alloc,
             }
@@ -469,7 +469,7 @@ impl<T, A: AllocRef> RawVec<T, A> {
     }
 
     fn set_memory(&mut self, memory: MemoryBlock) {
-        self.ptr = memory.ptr.cast().into();
+        self.ptr = unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) };
         self.cap = Self::capacity_from_bytes(memory.size);
     }
 

src/libcore/ptr/unique.rs

@@ -3,7 +3,6 @@ use crate::fmt;
 use crate::marker::{PhantomData, Unsize};
 use crate::mem;
 use crate::ops::{CoerceUnsized, DispatchFromDyn};
-use crate::ptr::NonNull;
 
 // ignore-tidy-undocumented-unsafe
 
@@ -171,19 +170,3 @@ impl<T: ?Sized> From<&mut T> for Unique<T> {
         unsafe { Unique { pointer: reference as *mut T, _marker: PhantomData } }
     }
 }
-
-#[unstable(feature = "ptr_internals", issue = "none")]
-impl<T: ?Sized> From<&T> for Unique<T> {
-    #[inline]
-    fn from(reference: &T) -> Self {
-        unsafe { Unique { pointer: reference as *const T, _marker: PhantomData } }
-    }
-}
-
-#[unstable(feature = "ptr_internals", issue = "none")]
-impl<T: ?Sized> From<NonNull<T>> for Unique<T> {
-    #[inline]
-    fn from(p: NonNull<T>) -> Self {
-        unsafe { Unique::new_unchecked(p.as_ptr()) }
-    }
-}