of the features that one might expect to be language features are library
features in Rust, so what you're looking for may be there, not here.
+Finally, this document is not normative. It may include details that are
+specific to `rustc` itself, and should not be taken as a specification for
+the Rust language. We intend to produce such a document someday, but this
+is what we have for now.
+
You may also be interested in the [grammar].
[book]: book/index.html