Macro access_mask 

macro_rules! access_mask {
    (
        $(#[$meta:meta])*
        $vis:vis struct $name:ident {
        $(
            $(#[$field_meta:meta])*
            $field_name:ident : $field_ty:ty,
        )*
    }) => { ... };
}

Macro for defining a bitfield for an access mask.

In windows, the upper word of access mask dword is always a set of common fields. Therefore, implementing this macro helps saving bunch of code for different access masks.

It’s input is the name of the struct to generate, and in {}, the list of fields to add before the common fields. include support for #[skip] fields, without visibility (all fields are public).