Support for 2018 edition?

[matthewpflueger]

Hi, I recently tried using ructe in a 2018 edition project. Unfortunately the templates are generated with the old style absolute paths like:

error[E0432]: unresolved import `templates`
 --> /opt/jezila/ructe/examples/simple/target/debug/build/simple-3b5f8e3dc18a428a/out/templates/template_list.rs:4:7
  |
use ::templates::{Html,ToHtml};
  |       ^^^^^^^^^ Did you mean `crate::templates`?

Is there a way to tell ructe to generate with new style paths (that start with crate)? Please excuse my ignorance if there is an obvious answer - I'm pretty new with Rust...

Love the library btw!

[kaj]

Thank you!

I havn't really looked at the 2018 edition concept yet, but yes, ideally ructe should recognize if the project it is a build dependency of has enabled the 2018 edition, and if so generate the new-style use lines. I don't know if that is possible.

If it can't be done "automagically", it could be either a parameter set in the build script or a feature defined on the dependency. I guess a future would be the best way then?

I'll look into it.

[kaj]

I have asked for an environment variable to use at https://users.rust-lang.org/t/detect-edition-2018-from-cargo-build-rs/21134 .

Failing that, I now think it would be better to actually look for an edition setting in $CARGO_MANIFEST_DIR/Cargo.toml than to require a feature flag or a call parameter in build.rs itself.

[kaj]

It seems that it is possible to formulate the use lines in such a way that they are compatible with both edition 2015 and edition 2018, so my current hope is that detecting edition 2018 should not be necessary. There are still some details that fails, but I hope to get back to it in a few hours.