Rust AVR backend

[brson]

Tracking issue so we have something to link to.

cc @dylanmckay @shepmaster. What's the status today?

[shepmaster]

With the LLVM 4 merge, changes we make to LLVM are easier to circle back into Rust for testing, but there's a lot of work to be done to address mis-generated code.

We are tracking what we know in the avr-rust issues. We also have a set of patches that have been applied to LLVM which we have cherry-picked into our fork of Rust's fork of Emscripten's fork of LLVM.

Most of the work now centers around trying to compile a piece of code and figuring out why it didn't.

We have also set up a gitter for communication in addition to the issue tracker.

Any other details you'd be interested in?

[brson]

Thanks @shepmaster. Seems like there's enough bugs left for the timeline to merge into Rust to be indeterminate.

[shepmaster]

I'm going to close this in favor of #44052; which will likely spawn another tracking issue in the future!