How do I fix Encodable/Decodable deprecation?

Question

A few repos (e.g. https://github.com/sebcrozet/nalgebra) have errors along the lines of

warning: deriving(Decodable) is deprecated in favor of deriving(RustcDeco         


        

Answer 1

I believe that your error comes from this commit:

This commit completes the deprecation story for the in-tree serialization library. The compiler will now emit a warning whenever it encounters deriving(Encodable) or deriving(Decodable), and the library itself is now marked #[unstable] for when feature staging is enabled.

All users of serialization can migrate to the rustc-serialize crate on crates.io which provides the exact same interface as the libserialize library in-tree. The new deriving modes are named RustcEncodable and RustcDecodable and require extern crate "rustc-serialize" as rustc_serialize at the crate root in order to expand correctly.

To migrate all crates, add the following to your Cargo.toml:

[dependencies]
rustc-serialize = "0.1.1"

And then add the following to your crate root:

extern crate "rustc-serialize" as rustc_serialize;

Finally, rename Encodable and Decodable deriving modes to RustcEncodable and RustcDecodable.