don't use drop_in_place as an intrinsic

Author: Gankra

src/doc/nomicon/destructors.md

@@ -26,12 +26,11 @@ this is totally fine.
 For instance, a custom implementation of `Box` might write `Drop` like this:
 
 ```rust
-#![feature(alloc, heap_api, core_intrinsics, unique)]
+#![feature(alloc, heap_api, drop_in_place, unique)]
 
 extern crate alloc;
 
-use std::ptr::Unique;
-use std::intrinsics::drop_in_place;
+use std::ptr::{drop_in_place, Unique};
 use std::mem;
 
 use alloc::heap;
@@ -58,12 +57,11 @@ use-after-free the `ptr` because when drop exits, it becomes inaccessible.
 However this wouldn't work:
 
 ```rust
-#![feature(alloc, heap_api, core_intrinsics, unique)]
+#![feature(alloc, heap_api, drop_in_place, unique)]
 
 extern crate alloc;
 
-use std::ptr::Unique;
-use std::intrinsics::drop_in_place;
+use std::ptr::{drop_in_place, Unique};
 use std::mem;
 
 use alloc::heap;
@@ -137,12 +135,11 @@ The classic safe solution to overriding recursive drop and allowing moving out
 of Self during `drop` is to use an Option:
 
 ```rust
-#![feature(alloc, heap_api, core_intrinsics, unique)]
+#![feature(alloc, heap_api, drop_in_place, unique)]
 
 extern crate alloc;
 
-use std::ptr::Unique;
-use std::intrinsics::drop_in_place;
+use std::ptr::{drop_in_place, Unique};
 use std::mem;
 
 use alloc::heap;

src/liballoc/arc.rs

@@ -77,7 +77,7 @@ use core::borrow;
 use core::fmt;
 use core::cmp::Ordering;
 use core::mem::{align_of_val, size_of_val};
-use core::intrinsics::{drop_in_place, abort};
+use core::intrinsics::abort;
 use core::mem;
 use core::ops::{Deref, CoerceUnsized};
 use core::ptr::{self, Shared};
@@ -304,7 +304,7 @@ impl<T: ?Sized> Arc<T> {
 
         // Destroy the data at this time, even though we may not free the box
         // allocation itself (there may still be weak pointers lying around).
-        drop_in_place(&mut (*ptr).data);
+        ptr::drop_in_place(&mut (*ptr).data);
 
         if self.inner().weak.fetch_sub(1, Release) == 1 {
             atomic::fence(Acquire);

src/liballoc/rc.rs

@@ -160,7 +160,7 @@ use core::cell::Cell;
 use core::cmp::Ordering;
 use core::fmt;
 use core::hash::{Hasher, Hash};
-use core::intrinsics::{assume, drop_in_place, abort};
+use core::intrinsics::{assume, abort};
 use core::marker::{self, Unsize};
 use core::mem::{self, align_of_val, size_of_val, forget};
 use core::ops::{CoerceUnsized, Deref};
@@ -460,7 +460,7 @@ impl<T: ?Sized> Drop for Rc<T> {
                 self.dec_strong();
                 if self.strong() == 0 {
                     // destroy the contained object
-                    drop_in_place(&mut (*ptr).value);
+                    ptr::drop_in_place(&mut (*ptr).value);
 
                     // remove the implicit "strong weak" pointer now that we've
                     // destroyed the contents.

src/libcollections/lib.rs

@@ -65,6 +65,7 @@
 #![feature(dropck_parametricity)]
 #![feature(unsafe_no_drop_flag, filling_drop)]
 #![feature(decode_utf16)]
+#![feature(drop_in_place)]
 #![cfg_attr(test, feature(clone_from_slice, rand, test))]
 
 #![feature(no_std)]

src/libcollections/vec.rs

@@ -65,7 +65,7 @@ use alloc::heap::EMPTY;
 use core::cmp::Ordering;
 use core::fmt;
 use core::hash::{self, Hash};
-use core::intrinsics::{arith_offset, assume, drop_in_place, needs_drop};
+use core::intrinsics::{arith_offset, assume, needs_drop};
 use core::iter::FromIterator;
 use core::mem;
 use core::ops::{Index, IndexMut, Deref};
@@ -1394,7 +1394,7 @@ impl<T> Drop for Vec<T> {
                 // Without the branch, dropping Vec<u8> takes linear time.
                 if needs_drop::<T>() {
                     for x in self.iter_mut() {
-                        drop_in_place(x);
+                        ptr::drop_in_place(x);
                     }
                 }
             }

src/libcore/intrinsics.rs

@@ -198,7 +198,7 @@ extern "rust-intrinsic" {
 
     /// Executes the destructor (if any) of the pointed-to value.
     ///
-    /// This has two usecases:
+    /// This has two use cases:
     ///
     /// * It is *required* to use `drop_in_place` to drop unsized types like
     ///   trait objects, because they can't be read out onto the stack and
@@ -209,7 +209,7 @@ extern "rust-intrinsic" {
     ///   as the compiler doesn't need to prove that it's sound to elide the
     ///   copy.
     ///
-    /// # Undefined Behaviour
+    /// # Undefined Behavior
     ///
     /// This has all the same safety problems as `ptr::read` with respect to
     /// invalid pointers, types, and double drops.

src/libstd/lib.rs

@@ -251,6 +251,8 @@
 #![feature(vec_push_all)]
 #![feature(wrapping)]
 #![feature(zero_one)]
+#![feature(drop_in_place)]
+
 #![cfg_attr(windows, feature(str_utf16))]
 #![cfg_attr(test, feature(float_from_str_radix, range_inclusive, float_extras))]
 #![cfg_attr(test, feature(test, rustc_private))]

src/libstd/thread/local.rs

@@ -411,7 +411,7 @@ mod imp {
         if cfg!(target_os = "macos") {
             ptr::read((*ptr).inner.get());
         } else {
-            intrinsics::drop_in_place((*ptr).inner.get());
+            ptr::drop_in_place((*ptr).inner.get());
         }
     }
 }

src/test/run-pass/extern_fat_drop.rs

@@ -10,14 +10,14 @@
 
 // aux-build:fat_drop.rs
 
-#![feature(core_intrinsics)]
+#![feature(drop_in_place)]
 
 extern crate fat_drop;
 
 fn main() {
     unsafe {
         let s: &mut fat_drop::S = std::mem::uninitialized();
-        std::intrinsics::drop_in_place(s);
+        std::ptr::drop_in_place(s);
         assert!(fat_drop::DROPPED);
     }
 }