Merge pull request #73 from Mark-Simulacrum/fix

Fix nomicon for allocator changes

Author: steveklabnik

src/destructors.md

@@ -28,17 +28,18 @@ For instance, a custom implementation of `Box` might write `Drop` like this:
 ```rust
 #![feature(ptr_internals, allocator_api, unique)]
 
-use std::alloc::{Global, GlobalAlloc, Layout};
+use std::alloc::{Alloc, Global, GlobalAlloc, Layout};
 use std::mem;
-use std::ptr::{drop_in_place, Unique};
+use std::ptr::{drop_in_place, NonNull, Unique};
 
 struct Box<T>{ ptr: Unique<T> }
 
 impl<T> Drop for Box<T> {
     fn drop(&mut self) {
         unsafe {
             drop_in_place(self.ptr.as_ptr());
-            Global.dealloc(self.ptr.as_ptr() as *mut _, Layout::new::<T>())
+            let c: NonNull<T> = self.ptr.into();
+            Global.dealloc(c.cast(), Layout::new::<T>())
         }
     }
 }
@@ -54,8 +55,8 @@ However this wouldn't work:
 ```rust
 #![feature(allocator_api, ptr_internals, unique)]
 
-use std::alloc::{Global, GlobalAlloc, Layout};
-use std::ptr::{drop_in_place, Unique};
+use std::alloc::{Alloc, Global, GlobalAlloc, Layout};
+use std::ptr::{drop_in_place, Unique, NonNull};
 use std::mem;
 
 struct Box<T>{ ptr: Unique<T> }
@@ -64,7 +65,8 @@ impl<T> Drop for Box<T> {
     fn drop(&mut self) {
         unsafe {
             drop_in_place(self.ptr.as_ptr());
-            Global.dealloc(self.ptr.as_ptr() as *mut _, Layout::new::<T>());
+            let c: NonNull<T> = self.ptr.into();
+            Global.dealloc(c.cast(), Layout::new::<T>());
         }
     }
 }
@@ -76,7 +78,8 @@ impl<T> Drop for SuperBox<T> {
         unsafe {
             // Hyper-optimized: deallocate the box's contents for it
             // without `drop`ing the contents
-            Global.dealloc(self.my_box.ptr.as_ptr() as *mut _, Layout::new::<T>());
+            let c: NonNull<T> = self.my_box.ptr.into();
+            Global.dealloc(c.cast::<u8>(), Layout::new::<T>());
         }
     }
 }
@@ -125,8 +128,8 @@ of Self during `drop` is to use an Option:
 ```rust
 #![feature(allocator_api, ptr_internals, unique)]
 
-use std::alloc::{GlobalAlloc, Global, Layout};
-use std::ptr::{drop_in_place, Unique};
+use std::alloc::{Alloc, GlobalAlloc, Global, Layout};
+use std::ptr::{drop_in_place, Unique, NonNull};
 use std::mem;
 
 struct Box<T>{ ptr: Unique<T> }
@@ -135,7 +138,8 @@ impl<T> Drop for Box<T> {
     fn drop(&mut self) {
         unsafe {
             drop_in_place(self.ptr.as_ptr());
-            Global.dealloc(self.ptr.as_ptr() as *mut _, Layout::new::<T>());
+            let c: NonNull<T> = self.ptr.into();
+            Global.dealloc(c.cast(), Layout::new::<T>());
         }
     }
 }
@@ -149,7 +153,8 @@ impl<T> Drop for SuperBox<T> {
             // without `drop`ing the contents. Need to set the `box`
             // field as `None` to prevent Rust from trying to Drop it.
             let my_box = self.my_box.take().unwrap();
-            Global.dealloc(my_box.ptr.as_ptr() as *mut _, Layout::new::<T>());
+            let c: NonNull<T> = my_box.ptr.into();
+            Global.dealloc(c.cast(), Layout::new::<T>());
             mem::forget(my_box);
         }
     }

src/vec-final.md

@@ -5,11 +5,11 @@
 #![feature(allocator_api)]
 #![feature(unique)]
 
-use std::ptr::{Unique, self};
+use std::ptr::{Unique, NonNull, self};
 use std::mem;
 use std::ops::{Deref, DerefMut};
 use std::marker::PhantomData;
-use std::alloc::{GlobalAlloc, Layout, Global, oom};
+use std::alloc::{Alloc, GlobalAlloc, Layout, Global, oom};
 
 struct RawVec<T> {
     ptr: Unique<T>,
@@ -38,18 +38,23 @@ impl<T> RawVec<T> {
                 (1, ptr)
             } else {
                 let new_cap = 2 * self.cap;
-                let ptr = Global.realloc(self.ptr.as_ptr() as *mut _,
+                let c: NonNull<T> = self.ptr.into();
+                let ptr = Global.realloc(c.cast(),
                                          Layout::array::<T>(self.cap).unwrap(),
                                          Layout::array::<T>(new_cap).unwrap().size());
                 (new_cap, ptr)
             };
 
             // If allocate or reallocate fail, oom
-            if ptr.is_null() {
-                oom()
+            if ptr.is_err() {
+                oom(Layout::from_size_align_unchecked(
+                    new_cap * elem_size,
+                    mem::align_of::<T>(),
+                ))
             }
+            let ptr = ptr.unwrap();
 
-            self.ptr = Unique::new_unchecked(ptr as *mut _);
+            self.ptr = Unique::new_unchecked(ptr.as_ptr() as *mut _);
             self.cap = new_cap;
         }
     }
@@ -60,7 +65,8 @@ impl<T> Drop for RawVec<T> {
         let elem_size = mem::size_of::<T>();
         if self.cap != 0 && elem_size != 0 {
             unsafe {
-                Global.dealloc(self.ptr.as_ptr() as *mut _,
+                let c: NonNull<T> = self.ptr.into();
+                Global.dealloc(c.cast(),
                                Layout::array::<T>(self.cap).unwrap());
             }
         }