Update to a new pinning API.
~~Blocked on #53843 because of method resolution problems with new pin type.~~
@r? @cramertj
cc @RalfJung @pythonesque anyone interested in #49150
doc: Clarify the lifetime returned by `Box::leak`
`Box::leak` mentions that it can return a `'static` reference, but it
wasn't immediately clear to me why it doesn't always do so. This is
because of the `T: 'a` constraint needed to form a valid reference, and
in general we want to be more flexible than requiring `T: 'static`.
This patch tries to clarify the relationship between `T` and `'a`.
`Box::leak` mentions that it can return a `'static` reference, but it
wasn't immediately clear to me why it doesn't always do so. This is
because of the `T: 'a` constraint needed to form a valid reference, and
in general we want to be more flexible than requiring `T: 'static`.
This patch tries to clarify the relationship between `T` and `'a`.
Inline most of the code paths for conversions with boxed slices
This helps with the specific problem described in #49541, obviously without making any large change to how inlining works in the general case.
Everything involved in the conversions is made `#[inline]`, except for the `<Vec<T>>::into_boxed_slice` entry point which is made `#[inline(always)]` after checking that duplicating the function mentioned in the issue prevented its inlining if I only annotate it with
`#[inline]`.
For the record, that function was:
```rust
pub fn foo() -> Box<[u8]> {
vec![0].into_boxed_slice()
}
```
To help the inliner's job, we also hoist a `self.capacity() != self.len` check in `<Vec<T>>::shrink_to_fit` and mark it as `#[inline]` too.
Some modules were still using the deprecated `allocator` module, use the
`alloc` module instead.
Some modules were using `super` while it's not needed.
Some modules were more or less ordering them, and other not, so the
latter have been modified to match the others.
94d1970bba moved the alloc::allocator
module to core::heap, moving e.g. Alloc and Layout out of the alloc
crate. While alloc::heap reexports them, it's better to use them from
where they really come from.
This helps with the specific problem described in #49541, obviously without
making any large change to how inlining works in the general case.
Everything involved in the conversions is made `#[inline]`, except for the
`<Vec<T>>::into_boxed_slice` entry point which is made `#[inline(always)]`
after checking that duplicating the function mentioned in the issue prevented
its inlining if I only annotate it with `#[inline]`.
For the record, that function was:
```rust
pub fn foo() -> Box<[u8]> {
vec![0].into_boxed_slice()
}
```
To help the inliner's job, we also hoist a `self.capacity() != self.len` check
in `<Vec<T>>::shrink_to_fit` and mark it as `#[inline]` too.
