Merge ref '425a9c0a0e36' from rust-lang/rust

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

Upstream ref: 425a9c0a0e365c0b8c6cfd00c2ded83a73bed9a0
Filtered ref: 7e955d5a6c676a099595bdfaec0705d3703e7a3c

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

Author: The Miri Cronjob Bot

src/SUMMARY.md

@@ -107,7 +107,6 @@
     - [Installation](./autodiff/installation.md)
     - [How to debug](./autodiff/debugging.md)
     - [Autodiff flags](./autodiff/flags.md)
-    - [Current limitations](./autodiff/limitations.md)
 
 # Source Code Representation