macro_rules! declare_features { ($( $(#[doc = $doc:tt])* (accepted, $feature:ident, $ver:expr, $issue:expr), )+) => { ... }; }
macro_rules! declare_features { ($( $(#[doc = $doc:tt])* (accepted, $feature:ident, $ver:expr, $issue:expr), )+) => { ... }; }