Missing "derive" feature for serde dependency?

[paulgoetze]

Hey Jérémie, I was just trying to update the Elixir mjml_nif lib to use mrml v1.2.2 and came across this error when compiling the crate:

Compiling mrml v1.2.2
error[E0433]: failed to resolve: could not find `Serialize` in `serde`
  --> /home/paul/.asdf/installs/rust/1.51.0/registry/src/github.com-1ecc6299db9ec823/mrml-1.2.2/src/mj_accordion/children.rs:16:44
   |
16 | #[cfg_attr(feature = "json", derive(serde::Serialize, serde::Deserialize))]
   |                                            ^^^^^^^^^ could not find `Serialize` in `serde`

error[E0433]: failed to resolve: could not find `Deserialize` in `serde`
  --> /home/paul/.asdf/installs/rust/1.51.0/registry/src/github.com-1ecc6299db9ec823/mrml-1.2.2/src/mj_accordion/children.rs:16:62
   |
16 | #[cfg_attr(feature = "json", derive(serde::Serialize, serde::Deserialize))]
   |                                                              ^^^^^^^^^^^ could not find `Deserialize` in `serde`

The dependencies in my Cargo.toml looked like this when compiling failed:

[dependencies]
rustler = "0.22.0-rc.1"
mrml = "1.2.2"

When I put an additonal explicit serde dependency with reference to its derive feature, like the following, compiling succeeds:

[dependencies]
rustler = "0.22.0-rc.1"
serde = { version = "1.0", features = ["derive"] }
mrml = "1.2.2"

(This also fetches an additional serde_derive v1.0.126)

I'm not too familiar with serde and the usage of macros, but might there be a missing features = ["derive"] for the serde dependency (or an explicit serde_derive dependency) in the mrml-core Cargo.toml?

Or did I miss sth. that changed from mrml v1.0.0 to v1.2.2 in terms of setup/installation?

[jdrouet]

@paulgoetze thanks for this issue, I completely forgot to update the installation steps. You do need to install serde = { version = "1.0", features = ["derive"] }.

If you don't need the json part, you can do the following

mrml = { version = "1.2", default-features = false, features = ["parse", "render"] }

[paulgoetze]

Thanks a lot @jdrouet - the latter works perfectly in my use case.
Also you get the Quickest-Maintainer-Reply-Award (weekend edition) 🏆 😉

[jdrouet]

Thank you very much! I'll keep it on my desk!