The below example code will generate VehicleDiscriminants enum with Car and Truck variants but it will be repr(usize) instead of inheriting the u8 repr of Vehicle additionally they will have the default enum representations (Car = 0 and Vehicle = 1 in this case)

// Custom discriminant tests
#[derive(EnumDiscriminants, Debug, PartialEq)]
#[strum_discriminants(derive(FromRepr))]
#[repr(u8)]
enum Vehicle {
    Car(CarModel) = 1,
    Truck(TruckModel) = 3,
}

I would have expected the above code to produce the following:

#[repr(u8)]
#[derive(FromRepr)]
enum VehicleDiscriminants {
    Car = 1,
    Truck = 3,
}