Merge ref '873d4682c7d2' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: rust-lang/rust@873d4682c7d285540b8f28bfe637006cef8918a6
Filtered ref: rust-lang/miri@57f1e8b76faa5c693897633867193c5f70b31337
Upstream diff: https://github.com/rust-lang/rust/compare/5a07626f4b8802d2baa260b76b2e1d0714674efe...873d4682c7d285540b8f28bfe637006cef8918a6

This merge was created using https://github.com/rust-lang/josh-sync.