Macro implement_decl 

macro_rules! implement_decl {
    (
        impl < $($gp:ident),+ $(,)? >
            $name:ident as $impl_vis:vis $impl_name:ident
        : [
            $( $ifty:ty ),+ $(,)?
        ]
        where $($wc:tt)+
    ) => { ... };
    (
        impl $name:ident as $impl_vis:vis $impl_name:ident : [
            $( $iface:ident ),+ $(,)?
        ] $(,)?
    ) => { ... };
}

Declares a Rust type as the COM implementer of one or more interfaces, without using the #[implement] proc-macro.