auto_impl has a few issues for beginners interested in working with the new proc macro API. With the crate auto_impl, you can easily implement your trait for certain "wrapper types" (e.g. &T where T: YourTrait).
We'd love to get more people involved! I'd be glad to mentor anyone interested in helping out.
I'm looking for someone to update the parser in macro_railroad, the syntax-diagram generator for macro_rules!()-syntax, to syn-0.15 (from 0.14). There are some bugs in the current parser which we also never got around to fixing. Tracking issue is here.
macro_railroad is looking for a contributor in the underlying syntax-diagram library: Most macros' syntax runs wide horizontally, making the resulting diagram hard to read on small screens. We can easily mitigate this in the underlying presentation layer by overflowing long-running Sequences into Stacks. The required primitives are basically already in place.
The content-security-policy spec is long. Implementing it and testing it takes all day just translating stuff from English to Rust; I figure many hands makes light work, if anyone's interested in working on a small corner of Servo and Ammonia.