Bump its stabilization version several times along
the way to accommodate changes in release processes.

Co-authored-by: Mara Bos <[email protected]>
Co-authored-by: Trevor Gross <[email protected]>

Stabilize const-weak-new

This is a fairly uncontroversial library stabilization, so I'm going ahead and proposing it to ride the trains to stable.

This stabilizes the following APIs, which are defined to be non-allocating constructors.

```rust
// alloc::rc
impl<T> Weak<T> {
    pub const fn new() -> Weak<T>;
}

// alloc::sync
impl<T> Weak<T> {
    pub const fn new() -> Weak<T>;
}
```

Closes rust-lang#95091

`@rustbot` modify labels: +needs-fcp

…ngjubilee

Use `LazyLock` to lazily resolve backtraces

By using TAIT to name the initializing closure, `LazyLock` can be used to replace the current `LazilyResolvedCapture`.

…-missing-opaque, r=spastorino

Don't install default projection bound for return-position `impl Trait` in trait methods with no body

This ensures that we never try to project to an opaque type in a trait method that has no body to infer its hidden type, which means we never later call `type_of` on that opaque. This is because opaque types try to reveal their hidden type when proving auto traits.

I thought about this a lot, and I think this is a fix that's less likely to introduce other strange downstream ICEs than rust-lang#113461.

r? `@spastorino`

…er-errors

Fix simd_bswap for i8/u8

rust-lang#114156 missed this test case ☹️
cc `@workingjubilee`

Fix empty_write since rust version attribute

Fixup of rust-lang#98154 for the rust version.

r? `@workingjubilee`