Make core::ops::Place an unsafe trait
Consumers of `Place` would reasonably expect that the `pointer` function returns a valid pointer to memory that can actually be written to.
Thew `_raw` prefix is included because the fact that `Box`’s ownership
semantics are "dissolved" or recreated seem more important than the exact
parameter type or return type.
Add Box::leak<'a>(Box<T>) -> &'a mut T where T: 'a
Adds:
```rust
impl<T: ?Sized> Box<T> {
pub fn leak<'a>(b: Box<T>) -> &'a mut T where T: 'a {
unsafe { &mut *Box::into_raw(b) }
}
}
```
which is useful for when you just want to put some stuff on the heap and then have a reference to it for the remainder of the program.
r? @sfackler
cc @durka
Improve raw Box conversions
This PR has two goals:
- Reduce use of `mem::transmute` in `Box` conversions
I understand that `mem::transmute`-ing non `#[repr(C)]` types is implementation-defined behavior. This may not matter within the reference implementation of Rust, but I believe it's important to remain consistent. For example, I noticed that `str::from_utf8_unchecked` went from using `mem::transmute` to using pointer casts.
- Make `Box` pointer conversions more straightforward regarding `Unique`
Provides a reasonable interface for Box::from_raw implementation.
Does not get around the requirement of mem::transmute for converting
back and forth between Unique and Box.
This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.
[RFC 1974]: https://github.com/rust-lang/rfcs/pull/197
The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.
cc #27389
Replaced by adding extra imports, adding hidden code (`# ...`), modifying
examples to be runnable (sorry Homura), specifying non-Rust code, and
converting to should_panic, no_run, or compile_fail.
Remaining "```ignore"s received an explanation why they are being ignored.
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
