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Any: use plain transmute instead of transmute_copy for downcasting. #19225

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Merged
merged 1 commit into from
Nov 23, 2014
Merged

Any: use plain transmute instead of transmute_copy for downcasting. #19225

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10 changes: 3 additions & 7 deletions src/liballoc/boxed.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,6 @@ use core::clone::Clone;
use core::cmp::{PartialEq, PartialOrd, Eq, Ord, Ordering};
use core::default::Default;
use core::fmt;
use core::intrinsics;
use core::kinds::Sized;
use core::mem;
use core::option::Option;
Expand Down Expand Up @@ -104,17 +103,14 @@ pub trait BoxAny {
}

#[stable]
impl BoxAny for Box<Any+'static> {
impl BoxAny for Box<Any> {
#[inline]
fn downcast<T: 'static>(self) -> Result<Box<T>, Box<Any+'static>> {
fn downcast<T: 'static>(self) -> Result<Box<T>, Box<Any>> {
if self.is::<T>() {
unsafe {
// Get the raw representation of the trait object
let to: TraitObject =
*mem::transmute::<&Box<Any>, &TraitObject>(&self);

// Prevent destructor on self being run
intrinsics::forget(self);
mem::transmute::<Box<Any>, TraitObject>(self);

// Extract the data pointer
Ok(mem::transmute(to.data))
Expand Down
6 changes: 3 additions & 3 deletions src/libcore/any.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@

#![stable]

use mem::{transmute, transmute_copy};
use mem::{transmute};
use option::{Option, Some, None};
use raw::TraitObject;
use intrinsics::TypeId;
Expand Down Expand Up @@ -134,7 +134,7 @@ impl<'a> AnyRefExt<'a> for &'a Any {
if self.is::<T>() {
unsafe {
// Get the raw representation of the trait object
let to: TraitObject = transmute_copy(&self);
let to: TraitObject = transmute(self);

// Extract the data pointer
Some(transmute(to.data))
Expand Down Expand Up @@ -162,7 +162,7 @@ impl<'a> AnyMutRefExt<'a> for &'a mut Any {
if self.is::<T>() {
unsafe {
// Get the raw representation of the trait object
let to: TraitObject = transmute_copy(&self);
let to: TraitObject = transmute(self);

// Extract the data pointer
Some(transmute(to.data))
Expand Down