[llvm] [bazel] Add MODULE.bazel (PR #164891)

[Jordan Rupprecht via llvm-commits]

rupprecht wrote:

> Hey! I'm the maintainer of `nanobind_bazel`. I came across this PR by accident, would you be willing to share some details on the build errors you encountered? I'd like to help fixing them if you are still interested.

Thanks for being a maintainer!

The build errors are link failures for libMLIRBindingsPythonCoreNoCAPI.so and libMLIRBindingsPythonCore.so: https://gist.github.com/rupprecht/ec8199ec929fe212f5b5ef967435efdc

Maybe those would be fixed if we also used the rules like `nanobind_extension` from your repo?

If you want to patch in and repro yourself:
* Replace the `nanobind` http_archive with `bazel_dep(name = "nanobind_bazel", version = "2.9.2", repo_name = "nanobind")`
* Run: `bazel build --enable_bzlmod --noenable_workspace --config=ci @llvm-project//mlir:MLIRBindingsPythonCore{,NoCAPI}`

I would definitely be interested in not having a local build file for nanobind (and robin_map). To keep changes small, I would like to do it separately from switching to bzlmod -- maybe that means only switching to your repo after switching to bzlmod, unless it'd be just as easy to use it w/ the WORKSPACE config, in which case we can do things in either order.

https://github.com/llvm/llvm-project/pull/164891