DRAFT: Add bzlmod support

[jamesreprise]

Added support for bzlmod. This allows bringing in rules_clojure via a MODULE.bazel file rather than through WORKSPACE.bazel, Bazel's support for which is planned to be removed "late 2025".

Usage

bazel_dep(name = "rules_clojure")
git_override(
    module_name = "rules_clojure",
    commit = "471f7b87b9752943412f3b358f8addf2feba8f4e",
    remote = "https://github.com/jamesreprise/rules_clojure.git",
)

clojure_tools_deps = use_repo_rule("@rules_clojure//rules:tools_deps.bzl", "clojure_tools_deps")

clojure_tools_deps(
    name = "deps",
    aliases = ["nrepl"],
    deps_edn = "//:deps.edn",
)

Todo

• Arrive on a satisfying approach for clojure_tools_deps referencing of the rules_clojure repository for running rules-clojure.gen-build.
• Add usage instructions to README.md
• Ideally, upload to the Bazel Central Registry so that consumers can depend with just
  bazel_dep(name = "rules_clojure", version = "x.y.z")

Notes

Mike Bland's ongoing series of blog posts on migrating to bzlmod was a useful resource.

[jamesreprise]

Decide on a version number.

[arohner]

I like the clojure tools.build convention of defaulting to "x.y.z" where x and y are user controlled, and z is the total number of git commits on master. tools.build has a script for computing z, I don't know whether bazel can help there.

[jamesreprise]

There's a new naming scheme for repositories, which has repository_ctx.attr.name return _main+_repo_rules+deps or similar rather than their given names. original_name was added in Bazel 8.1, but not backported to earlier versions. As a consequence, this PR will have rules_clojure not support the use of bzlmod on Bazel 7.x.

[jamesreprise]

Couldn't see these being referenced anywhere.

[jamesreprise]

I'm unsatisfied with this hack. I'd like to find a better way to get access to the genbuild code, whether that be by passing a reference into clojure_tools_deps or by finding the right attribute on repository_ctx.

[jamesreprise]

In #22 we introduced a methodology for pinning maven dependencies for WORKSPACE.bazel files that avoided polluting the maven namespace and requiring users to load the dependencies manually. See the rationale given by the original authors of the method: https://github.com/bazel-contrib/rules_jvm/blob/e153df2d3f3077690e0e423769908f66b1d7893f/docs/postfix.md

In bzlmod, neither of these benefits stand - when one module depends on another, the dependee's dependencies are not included in a global namespace, and users do not need to manually load transitive dependencies.

Therefore, we can 'skip' the frozen dependencies part and run maven.install using the name rules_clojure_maven_deps immediately, maintaining compatibility across WORKSPACE and bzlmod approaches.