Feature Request: Rust/Cargo Support for Building Native Extensions

[ianks]

Over the past few years, Rust has proven to be an incredibly stable and accessible option for those wishing to write native extensions for Ruby. Rust is particularly well-suited for Ruby for a few reasons:

1. Integration is straight-forward, since it is easy to expose a C compatible API using extern C.
2. Rust is a bit more high-level, and approachable for Ruby developers since it prevents many of the classic C footguns (use-after-free, etc)
3. The landing page can explain the benefits better than me. Check out https://www.rust-lang.org/ if you aren't fully convinced.

One of the biggest pain points of creating a Gem with a Rust extension is integrating with Gem::Ext::Builder. There are currently a couple of solutions, and the rely on the RakeBulider interface. I have personally used https://github.com/malept/thermite, which is a very good solution, but still requires and external dependency and does not integrate as well as native builders at the moment.

Currently, Gem::Ext::Builder supports four builder types: ExtConfBuilder, ConfigureBuilder, RakeBuilder, and CmakeBuilder. I propose we add a new builder, CargoBuilder, which will detect a Cargo.toml file and build the gem native extensions using cargo. This ease the burden of developing and publishing Rust extensions for Ruby users.

Potential Problems

1. If the user does not have cargo installed, building the extension will not work.
   This is an issue, but is also an issue for the CmakeBuilder. One way to mitigate this issue would be to make it easier to build static binaries for Rust extensions.

2. The lack of a standard ruby interface for Rust extensions might cause pain for developers.
   Currently, many folks use https://github.com/steveklabnik/ruby-sys to interface with the C ruby API. It might make sense to make this "officially" supported at some point, but I don't think it has to be done immediately.

Please let me know your thoughts. I would be very excited to see Ruby take this step. I don't think I know enough about the Ruby extension building process or the Rust compilation process to actually implement this, so hopefully we could find a volunteer to step up. Thanks for reading :)

Notable Gems using Rust

1. https://github.com/danielpclark/faster_path
2. https://github.com/ianks/fast_woothee -- shameless plug
3. https://github.com/tildeio/helix -- a framework for building Rust extensions
4. https://github.com/danielpclark/rutie -- ruby/rust glue
5. https://github.com/steveklabnik/ruby-sys -- low level bindings for ruby
6. https://github.com/malept/rusty_blank -- String#blank? with rust

[djberg96]

Seems like a nice idea.

Just curious, is this something that could be written as a plugin? Or is building too tightly integrated into the core?

If it can be made as a plugin, maybe it would be best to refactor all of the rubygems builders as plugins so they could be installed as needed, and more easily maintained, while reducing the burden on core rubygems itself.

[ianks]

@djberg96 That could potentially work. The problem I see is that if the plug-in is not bundled by default, it could be burdensome for the end-user (installer-of-gem) if they had to remember to do something like gem install rugygems-cargo-builder.

We could perhaps have a git-submodule which is hosted elsewhere if this proves to be too burdensome on rubygems maintainers. I'd be interested to hear input from someone from the Cargo team on this. Maybe @alexcrichton could chime in 😀

[alexcrichton]

I suspect that something like this would be best to start out in the community, and if it becomes large enough and is agreed it should become official, this seems reasonable to host in the rust-lang organization and have a team of maintainers there (not necessarily the same set as cargo maintainers!). I suspect though we'd want support for something like this to bake in the ecosystem a bit before adding to rust-lang though.

[djberg96]

@ianks I dunno, doesn't seem that burdensome to me, plus it would allow you full control over the code without having to get permission from the core rubygems team for every PR. Then once it's stable, we could consider merging into core.

[hsbt]

@ianks Hi, I welcome to cargo builder to rubygems. But I'm not familiar with rust-lang. Can you provide the patch for this? Thanks.

[ianks]

Yes @hsbt I will look into this ASAP

[johncallahan]

I think this is a great idea. I just had all sorts of issues publishing a Helix-powered gem to rubygems due to gemspec templating problems. The rindy gem is a Ruby wrapper for the Hyperledger Indy SDK. Testing the gem locally, then to github-based deployment (in Gemfile), then to rubygems.org was a headache.

[ianks]

I reached out to @malept to see if they are interested in porting parts of https://github.com/malept/thermite directly into rubygems. I think this would be the best way to tackle the v1. Let's give it a week or so to see if they respond.

[ianks]

It's been a couple of weeks now so I'm going to assume that @malept may be too busy to do this right now.

Does anyone want to tackle this issue? As mentioned earlier, https://github.com/malept/thermite is a great piece of prior art to reference, and we have support from some Rust developers to help review and make sure things are tidy.

If you are interested, or know someone who may be, drop a comment here 😁

[timmyjose]

Not directly apropos, but I have experience in Rust, and I've been using Ruby/Rails for a few months on the job now. I would like to participate and help out in this effort, whichever form it might take.

[pkondzior]

Maybe it would be easier to addd support of Rust into https://github.com/rake-compiler/rake-compiler, it seems that this gem already allows to easily build either C or Java extensions through coc approach.