f94d671bfa
This commit revisits the `cast` module in libcore and libstd, and scrutinizes
all functions inside of it. The result was to remove the `cast` module entirely,
folding all functionality into the `mem` module. Specifically, this is the fate
of each function in the `cast` module.
* transmute - This function was moved to `mem`, but it is now marked as
#[unstable]. This is due to planned changes to the `transmute`
function and how it can be invoked (see the #[unstable] comment).
For more information, see RFC 5 and #12898
* transmute_copy - This function was moved to `mem`, with clarification that is
is not an error to invoke it with T/U that are different
sizes, but rather that it is strongly discouraged. This
function is now #[stable]
* forget - This function was moved to `mem` and marked #[stable]
* bump_box_refcount - This function was removed due to the deprecation of
managed boxes as well as its questionable utility.
* transmute_mut - This function was previously deprecated, and removed as part
of this commit.
* transmute_mut_unsafe - This function doesn't serve much of a purpose when it
can be achieved with an `as` in safe code, so it was
removed.
* transmute_lifetime - This function was removed because it is likely a strong
indication that code is incorrect in the first place.
* transmute_mut_lifetime - This function was removed for the same reasons as
`transmute_lifetime`
* copy_lifetime - This function was moved to `mem`, but it is marked
`#[unstable]` now due to the likelihood of being removed in
the future if it is found to not be very useful.
* copy_mut_lifetime - This function was also moved to `mem`, but had the same
treatment as `copy_lifetime`.
* copy_lifetime_vec - This function was removed because it is not used today,
and its existence is not necessary with DST
(copy_lifetime will suffice).
In summary, the cast module was stripped down to these functions, and then the
functions were moved to the `mem` module.
transmute - #[unstable]
transmute_copy - #[stable]
forget - #[stable]
copy_lifetime - #[unstable]
copy_mut_lifetime - #[unstable]
[breaking-change]
86 lines
2.6 KiB
Rust
86 lines
2.6 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![feature(macro_rules)]
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use std::{option, mem};
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// Iota-reduction is a rule in the Calculus of (Co-)Inductive Constructions,
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// which "says that a destructor applied to an object built from a constructor
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// behaves as expected". -- http://coq.inria.fr/doc/Reference-Manual006.html
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//
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// It's a little more complicated here, because of pointers and regions and
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// trying to get assert failure messages that at least identify which case
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// failed.
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enum E<T> { Thing(int, T), Nothing((), ((), ()), [i8, ..0]) }
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impl<T> E<T> {
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fn is_none(&self) -> bool {
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match *self {
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Thing(..) => false,
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Nothing(..) => true
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}
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}
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fn get_ref<'r>(&'r self) -> (int, &'r T) {
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match *self {
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Nothing(..) => fail!("E::get_ref(Nothing::<{}>)", stringify!(T)),
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Thing(x, ref y) => (x, y)
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}
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}
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}
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macro_rules! check_option {
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($e:expr: $T:ty) => {{
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check_option!($e: $T, |ptr| assert!(*ptr == $e));
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}};
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($e:expr: $T:ty, |$v:ident| $chk:expr) => {{
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assert!(option::None::<$T>.is_none());
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let e = $e;
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let s_ = option::Some::<$T>(e);
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let $v = s_.get_ref();
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$chk
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}}
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}
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macro_rules! check_fancy {
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($e:expr: $T:ty) => {{
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check_fancy!($e: $T, |ptr| assert!(*ptr == $e));
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}};
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($e:expr: $T:ty, |$v:ident| $chk:expr) => {{
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assert!(Nothing::<$T>((), ((), ()), [23i8, ..0]).is_none());
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let e = $e;
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let t_ = Thing::<$T>(23, e);
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match t_.get_ref() {
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(23, $v) => { $chk }
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_ => fail!("Thing::<{}>(23, {}).get_ref() != (23, _)",
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stringify!($T), stringify!($e))
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}
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}}
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}
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macro_rules! check_type {
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($($a:tt)*) => {{
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check_option!($($a)*);
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check_fancy!($($a)*);
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}}
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}
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pub fn main() {
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check_type!(&17: &int);
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check_type!(box 18: Box<int>);
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check_type!(@19: @int);
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check_type!("foo".to_owned(): ~str);
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check_type!(vec!(20, 22): Vec<int> );
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let mint: uint = unsafe { mem::transmute(main) };
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check_type!(main: fn(), |pthing| {
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assert!(mint == unsafe { mem::transmute(*pthing) })
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});
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}
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