【Rust日报】 2019-08-16：Rust 1.37.0 稳定版已发布

type ByteOption = Option<u8>;

fn increment_or_zero(x: ByteOption) -> u8 {
    match x {
        ByteOption::Some(y) => y + 1,
        ByteOption::None => 0,
    }
}

impl Coin {
    fn value_in_cents(&self) -> u8 {
        match self {
            Self::Penny => 1,
            Self::Nickel => 5,
            Self::Dime => 10,
            Self::Quarter => 25,
        }
    }
}

/// Type size assertion where the first parameter
/// is a type and the second is the expected size.
#[macro_export]
macro_rules! static_assert_size {
    ($ty:ty, $size:expr) => {
        const _: [(); $size] = [(); ::std::mem::size_of::<$ty>()];
        //    ^ Note the underscore here.
    }
}

static_assert_size!(Option<Box<String>>, 8); // 1.
static_assert_size!(usize, 8); // 2.

#[repr(align(16))]
enum Align16 {
    Foo { foo: u32 },
    Bar { bar: u32 },
}

BufReader::buffer and BufWriter::buffer
Cell::from_mut
Cell::as_slice_of_cells
DoubleEndedIterator::nth_back
Option::xor
[{i,u}{8,16,32,64,128,size}::reverse_bits] and Wrapping::reverse_bits
slice::copy_within