Derive Macro Niche 

#[derive(Niche)]
{
    // Attributes available to this derive:
    #[niche]
}

Automatically derives a Niche implementation for a struct type.

You must mark one of the fields with a #[niche] attribute. This field’s type must already implement Niche. The None value for the struct will be uninitialized memory, except for the chosen field, which will be filled in with its None niche value. (This requires that the Niche implementation for the field’s type must have the same layout for its Self and Output types.)