Macro builtins

macro_rules! builtins {
    (@count) => { ... };
    (@count $first:tt $(, $rest:tt)*) => { ... };
    (@param_attr $default:ident) => { ... };
    (@param_attr $default:ident $name:expr) => { ... };
    (@types |$bcx:ident| { $($types_init:tt)* }
     @param_attrs |$op:ident| { $($attrs_init:tt)* }
     $($ident:ident = $(#[$attr:expr])* $name:ident($($(@[$param_attr:expr])? $params:expr),* $(,)?) $ret:expr),* $(,)?
    ) => { ... };
}

Available on crate feature ir only.