Closes rust-lang#106421

This was already fixed by
f5d43a0, but now the test cases are
added.

Fixes the explanation how to use is_finished to achieve a non-blocking
join. The updated version matches the documentation of the non-scoped
JoinHandle::is_finished.

Co-authored-by: matthewjasper <[email protected]>

Those libraries are build with `-C panic=unwind` and is expected to
be linkable to `-C panic=abort` library. To ensure unsoundness
compiler needs to prevent a `C-unwind` call to exist, as doing so may leak
foreign exceptions into `-C panic=abort`.

…r=Mark-Simulacrum

Add test cases for inlining compiler-private items

Closes rust-lang#106421

This was already fixed by rust-lang#121218, but now the test cases are added.

…slice, r=Mark-Simulacrum

Add examples for some methods on slices

Adds some examples to some methods on slice.

`is_empty` didn't have an example for an empty slice, even though `str` and the collections all have one, so I added that in.

`first_mut` and `last_mut` didn't have an example for what happens when the slice is empty, whereas `first` and `last` do, so I added that too.

…wjasper

match lowering: Split off `test_candidates` into several functions and improve comments

The logic of `test_candidates` has three steps: pick a test, sort the candidates, and generate code for everything. So I split it off into three methods.

I also ended up reworking the comments that explain the algorithm. In particular I added detailed examples. I removed the digression about rust-lang#29740 because it's no longer relevant to how the code is structured today.

r? `@matthewjasper`

…on, r=Mark-Simulacrum

Ignore compiletest test directive migration commits

Not sure if the corresponding bors commit need to be included as well, assuming not.

…-obk

promotion: don't promote int::MIN / -1

Looks like I entirely forgot about this case when adding the div-by-zero check, which was supposed to ensure that we never promote operations that can fail...
Cc rust-lang#80619

This is a breaking change, so needs a crater run.
r? `@oli-obk`

Fix incorrect doc of ScopedJoinHandle::is_finished

Fixes the explanation how to use `is_finished` to achieve a non-blocking join. The updated version matches the documentation of the non-scoped JoinHandle::is_finished.

Forbid use of `extern "C-unwind"` inside standard library

Those libraries are build with `-C panic=unwind` and is expected to be linkable to `-C panic=abort` library. To ensure unsoundness compiler needs to prevent a `C-unwind` call to exist, as doing so may leak foreign exceptions into `-C panic=abort`.

r? `@RalfJung`

Use `addr_of!`

As per rust-lang#121303 (comment)