This may fix #109

Thanks. I like the idea but i'd prefer this to be opt out rather than opt in for bindgen. I think we should be using environment variables for this too rather than Cargo features. It seems more of a built time problem rather than some configuration with extra features you enable.

While I do like the upgrade to Rust 2018 could you move that part to a separate PR.

Thanks again for the contribution.

The main reason to avoid bindgen is the heavy libclang/llvm dependency. It makes it harder to install, and takes long time to compile.

Unfortunately, env vars in Cargo can't disable dependencies. So even if it was controlled via an env flag, it'd still have the cost of system dependency and compile time.

The main reason to avoid bindgen is the heavy libclang/llvm dependency. It makes it harder to install, and takes long time to compile.

And is not really an option on Windows @ Azure Pipelines for example. I had to stick `syntect to a lower version to have CI working again. If it's not disabled by default, at least a feature that can be disabled like #113 would be great.

I've rebased this branch. I've also changed dependency's features=[] to default-features=false, because features is additive, so it didn't disable anything.

Oh, my bad, sorry.

Although I'm not a direct user of onig, it is in my dependency chain (of Tau, https://gitlab.gnome.org/World/Tau) and this PR has worked fine for me, avoiding me having to pull in lots of unnecessary deps.

Hopefully I should have some time over the next few days to work on rust-onig again. I'll have a go pulling together these PRs to refactor bindgen useage and publish a new crate version when I'm done.

Closing in favor of #126. Thanks!