Implement Encodable/Decodable traits for [T; 32+]

[noiseless]

As I can see it is possible to simply implement this by adding needed numbers to

array! {
32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16,
15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
}

(https://github.com/rust-lang-nursery/rustc-serialize/blob/master/src/serialize.rs#L1306)

What caused the current number of implementations?

I want to serialize [u8, 64], now for this I need to create my own type and to write implementation for it, there is no way to create trait implementation for non-foreing type (rust-lang/rfcs#1023).

[bluss]

The number is of course arbitrary, but libstd itself is using 0–32 inclusive as well. Past that range, arrays don't impl PartialEq or AsRef etc, a range of traits. So there's a certain consistency.

[dtolnay]

In Serde we plan to support this by generating smarter code rather than by extending the array impls to bigger sizes. serde-rs/serde#631

#[derive(Serialize)]
struct S {
    array: [u8; 64],
}

Here the generated code should see that the array is bigger than our biggest array impl so it should generate a loop to serialize the array rather than trying to delegate to [u8; 64]'s implementation of Serialize (which doesn't exist).

[alexcrichton]

I'm going to close this now that this crate is deprecated in favor of serde. We're discontinuing feature development in rustc-serialize but will still continue to merge bug fixes if they arise.