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Any: use plain transmute instead of transmute_copy for downcasting.

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transmute_copy is no longer needed and is just slow.
This commit is contained in:
Jonathan Reem 2014-11-22 16:06:21 -08:00
parent 0d0a290614
commit 1b17eefa4a
2 changed files with 6 additions and 10 deletions
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10
src/liballoc/boxed.rs
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@ -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;
@ -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))

6
src/libcore/any.rs
View File

@ -71,7 +71,7 @@
#![stable]
use mem::{transmute, transmute_copy};
use mem::{transmute};
use option::{Option, Some, None};
use raw::TraitObject;
use intrinsics::TypeId;
@ -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))
@ -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))