Macro define_index_type

macro_rules! define_index_type {
    (
    $(#[$attrs:meta])*
    $v:vis struct $type:ident for $target:ident $(<$($l:lifetime),*>)? = $raw:ident;
    $($CONFIG_NAME:ident = $value:expr;)* $(;)?
  ) => { ... };
}

Creates a new index type and associates it with an object type.

This is a thin wrapper around index_vec::define_index_type. The only modification is the for $TYPE syntax that generates the IndexedValue implementation.