# As-yet-undocumented Features

Several accepted, stabilized, and implemented RFCs lack documentation in this reference, The Book, Rust by Example, or some combination of those three. Until we have written reference documentation for these features, we provide links to other sources of information about them. Therefore, expect this list to shrink!

- `libstd` facade
- Trait reform – some partial documentation exists (the use of `Self`), but not for everything: e.g. coherence and orphan rules.
- Attributes on `match` arms – the underlying idea is documented in the [Attributes] section, but the applicability to internal items is never specified.
- Flexible target specification - Some---but not all---flags are documented in Conditional compilation
- [Require parentheses for chained comparisons]
- `dllimport` - one element mentioned but not explained at FFI attributes
- define `crt_link`
- define `unaligned_access`