Method reserve

src/derive/option.rs:81–84

(&mut self, additional: NonZeroUsize)

    }

    fn reserve(&mut self, additional: NonZeroUsize) {
        self.variants.reserve(additional);
        // We don't know how many are Some, so we can't reserve more.
    }
}

pub struct OptionDecoder<'a, T: Decode<'a>> {