Added the following (all unstable):

* Defaulted type pararameter `A: Allocator`.
* `UniqueRc::new_in()`.
* `T:  ?Sized` where possible.
* `impl CoerceUnsized for UniqueRc`.
* Drive-by doc polish: links and periods at the end of sentences.

These changes are motivated by supporting the implementation of unsized
`Rc::make_mut()` (PR rust-lang#116113), but are also intended to be obvious
generalizations of `UniqueRc` to support the things `Rc` does.

Since we support solaris 11 and macOs Sierra as minimum, we can get rid
of the runtime overhead.

… candidates

We don't build LLVM when using the precompiled version from the CI builder.

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Always emit `native-static-libs` note, even if it is empty

Fixes rust-lang#108825.

change method resolution to constrain hidden types instead of rejecting method candidates

Some of these are in probes and may affect inference. This is therefore a breaking change.

This allows new code to compile on stable:

```rust
trait Trait {}

impl Trait for u32 {}

struct Bar<T>(T);

impl Bar<u32> {
    fn foo(self) {}
}

fn foo(x: bool) -> Bar<impl Sized> {
    if x {
        let x = foo(false);
        x.foo();
        //^ this used to not find the `foo` method, because while we did equate `x`'s type with possible candidates, we didn't allow opaque type inference while doing so
    }
    todo!()
}
```

r? `````@compiler-errors`````

fixes  rust-lang#121404

cc rust-lang#116652

`UniqueRc`: support allocators and `T: ?Sized`.

Added the following (all unstable):

* Defaulted type pararameter `A: Allocator`.
* `UniqueRc::new_in()`.
* `T:  ?Sized` where possible.
* `impl CoerceUnsized for UniqueRc`.

These changes are motivated by supporting the implementation of unsized `Rc::make_mut()` (PR rust-lang#116113), but are also intended to be obvious generalizations of `UniqueRc` to support the things `Rc` does.

r? ```@the8472```

…rochenkov

Add pub struct with allow(dead_code) into worklist

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Fixes rust-lang#126289

Avoid ICES after reporting errors on erroneous patterns

fixes rust-lang#109812
fixes rust-lang#125914
fixes rust-lang#124004

Remove some msys2 utils

`dos2unix` should no longer be necessary. I suspect `diffutils` might not be needed either as (I think) only `diff` is used and that seems to be shipped with git bash at least.

try-job: x86_64-msvc
try-job: x86_64-msvc-ext
try-job: dist-x86_64-msvc

std::unix::fs::link using direct linkat call for Solaris.

Since we support solaris 11 as minimum, we can get rid of the runtime overhead.

try-job: dist-various-2

extend the check for LLVM build

We don't build LLVM when using the precompiled version from the CI builder.

Closes rust-lang#126156