This is the first (known) step towards starting to use `unix_sigpipe` in
the wild. Eventually, `rustc_driver::set_sigpipe_handler` can be removed
and all clients can use `unix_sigpipe` instead.

For now we just start using `unix_sigpipe` in once place: `rustc`
itself.

It is easy to manually verify this change. If you remove
`#[unix_sigpipe = "sig_dfl"]` and run `./x.py build` you will get an ICE
when you do `./build/x86_64-unknown-linux-gnu/stage1/bin/rustc --help |
false`. Add back `#[unix_sigpipe = "sig_dfl"]` and the ICE disappears
again.

These targets have system limits on the thread names, 16 and 64 bytes
respectively, and `pthread_setname_np` returns an error if the name is
longer. However, we're not in a context that can propagate errors when
we call this, and we used to implicitly truncate on Linux with `prctl`,
so now we manually truncate these names ahead of time.

Co-authored-by: Amanieu d'Antras <amanieu@gmail.com>

Stabilize `Option::unzip()`

Stabilizes `Option::unzip()`, closes rust-lang#87800

`@rustbot` modify labels: +T-libs-api

…h726

rustc: Use `unix_sigpipe` instead of `rustc_driver::set_sigpipe_handler`

This is the first (known) step towards starting to use `unix_sigpipe` in the wild. Eventually, `rustc_driver::set_sigpipe_handler` can be removed and all clients can use `unix_sigpipe` instead.

For now we just start using `unix_sigpipe` in one place: `rustc` itself.

It is easy to manually verify this change. If you remove `#[unix_sigpipe = "sig_dfl"]` and run `./x.py build` you will get an ICE when you do `./build/x86_64-unknown-linux-gnu/stage1/bin/rustc --help | false`. Add back `#[unix_sigpipe = "sig_dfl"]` and the ICE disappears again.

PR that added `set_sigpipe_handler`: rust-lang#49606

Tracking issue for `unix_sigpipe`: rust-lang#97889

Not sure exactly how to label this PR. Going with T-libs for now since this is a T-libs feature.

``@rustdoc`` labels +T-libs

Prevent foreign Rust exceptions from being caught

Fix rust-lang#102715

Use the address of a static variable (which is guaranteed to be unique per copy of std) to tell apart if a Rust exception comes from local or foreign Rust code, and abort for the latter.

Remove misc_cast and validate types when casting

Continuing our work in rust-lang#102675

r? ``@oli-obk``

…omcc

Truncate thread names on Linux and Apple targets

These targets have system limits on the thread names, 16 and 64 bytes
respectively, and `pthread_setname_np` returns an error if the name is
longer. However, we're not in a context that can propagate errors when
we call this, and we used to implicitly truncate on Linux with `prctl`,
so now we manually truncate these names ahead of time.

r? ````@thomcc````

…llot

Name the `impl Trait` in region bound suggestions

Slightly more descriptive message