Auto merge of #56352 - alexcrichton:beta-next, r=alexcrichton

Rollup beta backports

* https://github.com/rust-lang/rust/pull/56264
* https://github.com/rust-lang/rust/pull/56300
* https://github.com/rust-lang/rust/pull/56322
* https://github.com/rust-lang/rust/pull/56329

Neither https://github.com/rust-lang/rust/pull/56300 nor https://github.com/rust-lang/rust/pull/56329 applied cleanly, but I think I've gotten it working with @nikic's [help](https://github.com/rust-lang/rust/pull/56300#issuecomment-442950648) (thanks!)

Closes https://github.com/rust-lang/rust/issues/56311
Closes https://github.com/rust-lang/rust/issues/56263