Macro const_type::Const

macro_rules! Const {
    (
    $(  #[  $Config:meta ]  )*
    $Visibility:vis $Struct:ident: $Type:ty
    {
      $(
        $(  #[  $Variant:meta ]  )*
        $Const:ident                 =   $Value:expr$(,)*
      )*
    }
  ) => { ... };
    (
    $(  #[  $Config:meta ]  )*
    $Visibility:vis $Struct:ident
    {
      $(
        $(  #[  $Variant:meta ]  )*
        $Const:ident                    =   $Value:expr$(,)*
      )*
    }
  ) => { ... };
}

With Const! enum-like const-types, but with aliases for variants, can be defined.