Fix MODULE example in README

[rhaps0dy]

The previous example in README failed with error:

ERROR: Analysis of target '//project_template/cpp:main' failed; build aborted: The module extension defined at /home/dev/.cache/bazel/_bazel_dev/0a671fc952be90f724e819c56b1dda7d/external/rules_cuda+/cuda/extensions.bzl:42:29 does not have a tag class named toolkit, but its use is attempted at /home/dev/llm/MODULE.bazel:4:13

we have to import toolkit instead of toolchain from cuda.

Also took the chance to bump rules_cuda.

[cloudhan]

Sorry, my bad. Seems to be a mis-editting with bulk replace.

It seem does not have a tag class named toolkit using toolkit in your module, but toolchain is expected. So the example is in correct form.

[sebastian-sz]

@cloudhan Could you elaborate? The core example on the main branch does not seem to be correct:

# MODULE.bazel
bazel_dep(name = "rules_cuda", version = "0.2.1")
cuda = use_extension("@rules_cuda//cuda:extensions.bzl", "toolchain")
cuda.toolkit(
    name = "cuda",
    toolkit_path = "",
)
use_repo(cuda, "cuda")

Will fail:

root@a94b8f573df5:/workspace# bazel run //:mybin
ERROR: Analysis of target '//:mybin' failed; build aborted: The module extension defined at /root/.cache/bazel/_bazel_root/eab0d61a99b6696edb3d2aff87b585e8/external/rules_cuda+/cuda/extensions.bzl:42:29 does not have a tag class named toolkit, but its use is attempted at /workspace/MODULE.bazel:10:13
INFO: Elapsed time: 0.300s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target

But replacing to:
cuda = use_extension("@rules_cuda//cuda:extensions.bzl", "toolkit")
will correctly compile the code.

[cloudhan]

You should use commit from main branch. The behavior is tested in CI and cannot be wrong.

rules_cuda/tests/integration/toolchain_root/MODULE.bazel

Lines 4 to 9 in 28177e2

	local_path_override(
	module_name = "rules_cuda",
	path = "../../..",
	)
	cuda = use_extension("@rules_cuda//cuda:extensions.bzl", "toolchain")

So this is not a fix, it is a break.

[sebastian-sz]

@cloudhan Thank you for the comment and the explanation. Using toolchain indeed does work on the current main branch.

bazel_dep(name = "rules_cuda", version = "0.2.3")
cuda = use_extension("@rules_cuda//cuda:extensions.bzl", "toolchain")
archive_override(
    module_name = "rules_cuda",
    integrity = "sha256-9PahCCOjx6Kqp2PFugoJEi09fXQBSsiOCxPbQbnMnFk=",
    url = "https://github.com/bazel-contrib/rules_cuda/archive/28177e2283a16b1e81c229e9bdc5610f1f3b07f7.tar.gz",
    strip_prefix = "rules_cuda-28177e2283a16b1e81c229e9bdc5610f1f3b07f7",
)

Do you think we could update the docs, for the MODULE.bazel install? Something like
"using toolchain is recommended onwards, for previous releases use toolkit"

I think it would help a lot with setting up the rules for the first timers. I'd be happy to submit such PR, let me how you feel about this.