Home for the Unsafe Code Guidelines effort. The goal of the Unsafe Code Guidelines effort is to collaboratively produce a "reference guide" to write unsafe code. This guide should ultimately be a formal specification of what kinds of things unsafe code can and cannot do. However, we are not there yet.
The primary document in this repo is the "Unsafe Code Guidelines Reference". It is largely a work-in-progress right now. It serves as a kind of table of contents to the sorts of questions that are on our radar, as well as place to collect notes and summaries about those questions.
Since we are not yet at the point where we can provide complete, definitive answers, the current goal for each section is to describe the "contours of the space". For example, we would try to specify what kinds of invariants must hold, as well as things that we expect to never be true. For other cases where there is disagreement, we will try to summarize the various options on the table -- you would do well in your unsafe code to steer clear of relying on those details.
The Unsafe Code Guidelines WG is in the process of being rebooted. We expect to be holding regular meetings focused on particular topics. Stay tuned for more announcements. -- @nikomatsakis
The Rustonomicon is a draft document discussing unsafe code. It is intended to be brought into agreement with the content here. It represents an organized effort to explain how to write Rust code, rather than a reference.
The nikomatsakis/rust-memory-model repository was a previous effort and contains a lot of good links and info.