Reviving rust-chamber in 2023

[alexpyattaev]

Hi! I've found this project to be super interesting as a candidate for scripting engine in a game. However, it was built long ago in a galaxy far far away. In your estimate, what would it take to make it work with modern rustc?

[brson]

The main thing chamber did was add custom lints to the compiler. It may be possible to do this with https://github.com/trailofbits/dylint now, and then just run the compiler as normal, where chamber actually used the compiler as a library.

If dylint isn't powerful enough to reject everything chamber needs to, then it appears that the same basic plugin_registrar mechanism continues to exist inside rustc, though I gather it is unsupported and will never be stabilized, will be removed someday.

It's still probably possible to write a custom compiler driver that uses rustc as a library, though rustc internals have completely changed.

What existed of chamber, just a prototype really, is a tiny amount of code, so it should be feasible to rewrite it from scratch following essentially the same strategy - use rustc as a library, load a custom plugin through the unsupported internal plugin api. It probably wouldn't take more than a day to prove the concept again.

[brson]

Also, since the mechanism to link to other crates has changed, and is no longer syntactic (extern crate), some other mechanism besides lints needs to be used to reject linkage.

[alexpyattaev]

Thanks for the advice!
As for rejecting linkage that is fairly easy as long as the project's Cargo.toml is controlled. In this case any crate not mentioned there would simply fail to import. I'd expect that any sandboxing effort would control Cargo.toml and build.rs first and foremost. Or am I missing an obvious problem with that?

As for using linter instead of a compiler plugin, that does sound rather interesting. I suppose one could enforce the filtering on use statements, and from that ensure the sandbox is tight. Though re-exports will be tricky to keep under control (as the same thing may get reexported under a different name from a different crate. I'll need to dig into dylint then =)