Enable Bzlmod

All but finishes bazelbuild#1482, barring the release and publication to the Bazel
Central Registry.

New `MODULE.bazel` files mirroring existing `WORKSPACE` configurations
comprise the bulk of the commit. The empty `WORKSPACE.bzlmod` files
ensure that Bzlmod won't evaluate the existing `WORKSPACE` files.

These new files comprise the most significant part of the change:

- `scala/extensions/config.bzl`
- `scala/extensions/deps.bzl`
- `scala/private/extensions/dev_deps.bzl`
- `scala/private/macros/bzlmod.bzl`

`config.bzl`, `deps.bzl`, and `dev_deps.bzl` are thoroughly tested by
existing tests. The following files thoroughly test the helpers from
`scala/private/macros/bzlmod.bzl` specifically:

- scala/private/macros/test/...
- test/shell/test_bzlmod_macros.sh

The pattern employed throughout the new module extensions is explained
in the `scala/private/macros/bzlmod.bzl` docstring.

Adding `test/shell/test_bzlmod_macros.sh` also precipitated adding a new
`assert_matches` helper to `test/shell/test_helper.sh`.
`test/shell/test_helper.sh` also introduces a mechanism for
automatically finding and skipping tests, documented in the comment at
the bottom of the file.

"Publish to BCR" configuration in the `.bcr` directory comes from:

- https://github.com/bazel-contrib/publish-to-bcr/tree/main/templates

The bazel-contrib/publish-to-bcr README contains further guidance on
configuring the app. Once that's done, we can use the app to publish a
new version to https://registry.bazel.build/ and then close bazelbuild#1482.

This change enables Bazel 7 and 8 users to migrate their `rules_scala`
dependency from `WORKSPACE` to `MODULE.bazel` whenever they're ready.

Stardoc inspired doc updates

.bazelci/presubmit.yml

@@ -29,17 +29,15 @@ tasks:
     # Install xmllint
     - sudo apt update && sudo apt install --reinstall libxml2-utils -y
     - "./test_rules_scala.sh"
-  # Switch `last_rc` to `last_green` once Bzlmod lands.
-  # https://github.com/bazelbuild/rules_scala/issues/1482
-  test_rules_scala_linux_last_rc:
-    name: "./test_rules_scala (last_rc Bazel)"
+  test_rules_scala_linux_last_green:
+    name: "./test_rules_scala (last_green Bazel)"
     platform: ubuntu2004
-    bazel: last_rc
+    bazel: last_green
     shell_commands:
     # Install xmllint
     - sudo apt update && sudo apt install --reinstall libxml2-utils -y
     - echo "build --enable_workspace" >> .bazelrc
-    - "./test_rules_scala.sh || buildkite-agent annotate --style 'warning' \"Optional build with last_rc Bazel version failed, [see here](${BUILDKITE_BUILD_URL}#${BUILDKITE_JOB_ID}) (It is not mandatory but worth checking)\""
+    - "./test_rules_scala.sh || buildkite-agent annotate --style 'warning' \"Optional build with last_green Bazel version failed, [see here](${BUILDKITE_BUILD_URL}#${BUILDKITE_JOB_ID}) (It is not mandatory but worth checking)\""
   test_rules_scala_macos:
     name: "./test_rules_scala"
     platform: macos

.bazelignore

@@ -0,0 +1,19 @@
+# Remove once the following is fixed:
+# - bazelbuild/bazel: Loading top-level targets in local_path_override modules
+#   in child directory breaks the build #22208
+#   https://github.com/bazelbuild/bazel/issues/22208
+dt_patches/compiler_sources
+dt_patches/test_dt_patches
+dt_patches/test_dt_patches_user_srcjar
+examples/crossbuild
+examples/overridden_artifacts
+examples/scala3
+examples/semanticdb
+examples/testing/multi_frameworks_toolchain
+examples/testing/scalatest_repositories
+examples/testing/specs2_junit_repositories
+test/proto_cross_repo_boundary/repo
+test_cross_build
+third_party/test/example_external_workspace
+third_party/test/new_local_repo
+third_party/test/proto

.bazelrc

@@ -1,6 +1,5 @@
-# Switch to --noenable_workspace when Bzlmod lands.
-# https://github.com/bazelbuild/rules_scala/issues/1482
-common --enable_workspace --noenable_bzlmod
+# Remove once Bazel 8 becomes the default supported version.
+common --noenable_workspace
 
 # Remove once proto toolchainization becomes the default
 # - https://bazel.build/reference/command-line-reference#flag--incompatible_enable_proto_toolchain_resolution

.bcr/metadata.template.json

@@ -0,0 +1,20 @@
+{
+  "homepage": "https://github.com/bazelbuild/rules_scala",
+  "maintainers": [
+    {
+      "name": "Simonas Pinevičius",
+      "email": "simonas.pinevicius@gmail.com",
+      "github": "simuons"
+    },
+    {
+      "name": "Vaidas Pilkauskas",
+      "email": "vaidas.pilkauskas@gmail.com",
+      "github": "liucijus"
+    }
+  ],
+  "repository": [
+    "github:bazelbuild/rules_scala"
+  ],
+  "versions": [],
+  "yanked_versions": {}
+}

.bcr/presubmit.yml

@@ -0,0 +1,14 @@
+# We recommend included a bcr test workspace that exercises your ruleset with bzlmod.
+# For an example, see https://github.com/aspect-build/bazel-lib/tree/main/e2e/bzlmod.
+bcr_test_module:
+  module_path: "examples/crossbuild"
+  matrix:
+    platform: ["debian10", "macos", "ubuntu2004", "windows"]
+    bazel: [6.x, 7.x]
+  tasks:
+    run_tests:
+      name: "Run test module"
+      platform: ${{ platform }}
+      bazel: ${{ bazel }}
+      test_targets:
+        - "//..."

.bcr/source.template.json

@@ -0,0 +1,5 @@
+{
+  "integrity": "",
+  "strip_prefix": "{REPO}-{VERSION}",
+  "url": "https://github.com/{OWNER}/{REPO}/releases/download/{TAG}/{REPO}-{TAG}.tar.gz"
+}

.gitignore

@@ -16,3 +16,9 @@ test/semanticdb/tempsrc
 
 # From scripts/create_repository.py
 repository-artifacts.json
+
+# Until it settles down
+**/MODULE.bazel.lock
+
+# Used by some tests, but can also be used for local experimentation.
+tmp/

MODULE.bazel

@@ -0,0 +1,279 @@
+"""Bazel module definition for rules_scala"""
+
+module(
+    name = "rules_scala",
+    version = "7.0.0",
+    compatibility_level = 7,
+    bazel_compatibility = [">=7.5.0"],
+)
+
+SCALA_VERSION = "2.12.20"
+
+# These versions match those required by some tests, including
+# test_thirdparty_version.sh.
+SCALA_2_VERSIONS = [
+    "2.11.12",
+    "2.12.20",
+    "2.13.16",
+]
+
+SCALA_3_VERSIONS = [
+    "3.1.3",
+    "3.3.5",
+    "3.5.2",
+    "3.6.3",
+]
+
+SCALA_VERSIONS = SCALA_2_VERSIONS + SCALA_3_VERSIONS
+
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "platforms", version = "0.0.11")
+bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "rules_java", version = "8.9.0")
+bazel_dep(name = "rules_proto", version = "7.1.0")
+
+bazel_dep(
+    name = "protobuf",
+    version = "29.3",
+    repo_name = "com_google_protobuf",
+)
+
+# Temporarily required for `protoc` toolchainization until resolution of
+# protocolbuffers/protobuf#19679.
+single_version_override(
+    module_name = "protobuf",
+    version = "29.3",
+    patches = ["//protoc:0001-protobuf-19679-rm-protoc-dep.patch"],
+    patch_strip = 1,
+)
+
+scala_config = use_extension(
+    "//scala/extensions:config.bzl",
+    "scala_config",
+)
+use_repo(scala_config, "rules_scala_config")
+
+dev_config = use_extension(
+    "//scala/extensions:config.bzl",
+    "scala_config",
+    dev_dependency = True,
+)
+dev_config.settings(
+    enable_compiler_dependency_tracking = True,
+    scala_version = SCALA_VERSION,
+    scala_versions = SCALA_VERSIONS,
+)
+
+scala_deps = use_extension("//scala/extensions:deps.bzl", "scala_deps")
+
+# This is optional, but still safe to include even when not using
+# `--incompatible_enable_proto_toolchain_resolution`.
+register_toolchains("//protoc:all")
+
+# Register some of our testing toolchains first when building our repo.
+register_toolchains(
+    "//scala:unused_dependency_checker_error_toolchain",
+    "//test/proto:scalapb_toolchain",
+    "//test/toolchains:java21_toolchain_definition",
+    dev_dependency = True,
+)
+
+use_repo(
+    scala_deps,
+    "rules_scala_toolchains",
+    "scala_compiler_sources",
+)
+
+register_toolchains("@rules_scala_toolchains//...:all")
+
+# Dev dependencies
+
+dev_deps = use_extension(
+    "//scala/extensions:deps.bzl",
+    "scala_deps",
+    dev_dependency = True,
+)
+dev_deps.toolchains(
+    jmh = True,
+    scala_proto = True,
+    scalafmt = True,
+    scalatest = True,
+    junit = True,
+    specs2 = True,
+    twitter_scrooge = True,
+)
+
+use_repo(
+    dev_deps,
+    "scala_proto_rules_scalapb_compilerplugin",
+    "scala_proto_rules_scalapb_protoc_bridge",
+    "scalafmt_default",
+)
+
+# Default versions of version specific repos needed by some of our tests. Tests
+# that set `--repo_env=SCALA_VERSION=...` break without using the default here,
+# because version specific repos for other versions won't be available.
+use_repo(
+    dev_deps,
+    "io_bazel_rules_scala_guava",
+    "io_bazel_rules_scala_junit_junit",
+    "io_bazel_rules_scala_scala_compiler",
+    "io_bazel_rules_scala_scala_library",
+)
+
+[
+    [
+        use_repo(dev_deps, dep + "_" + scala_version.replace(".", "_"))
+        for dep in [
+            "io_bazel_rules_scala_junit_junit",
+            "io_bazel_rules_scala_scala_compiler",
+            "io_bazel_rules_scala_scala_library",
+        ] + (
+            # We can remove this condition once we drop support for Scala 2.11.
+            ["scala_proto_rules_scalapb_protoc_gen"]
+            if not scala_version.startswith("2.11.") else []
+        )
+    ]
+    for scala_version in SCALA_VERSIONS
+]
+
+[
+    [
+        use_repo(dev_deps, dep + "_" + scala_version.replace(".", "_"))
+        for dep in [
+            "io_bazel_rules_scala_scala_reflect",
+        ]
+    ]
+    for scala_version in SCALA_2_VERSIONS
+]
+
+[
+    [
+        use_repo(dev_deps, dep + "_" + scala_version.replace(".", "_"))
+        for dep in [
+            "io_bazel_rules_scala_scala_compiler_2",
+            "io_bazel_rules_scala_scala_library_2",
+            "io_bazel_rules_scala_scala_reflect_2",
+        ]
+    ]
+    for scala_version in SCALA_3_VERSIONS
+]
+
+internal_dev_deps = use_extension(
+    "//scala/private/extensions:dev_deps.bzl",
+    "dev_deps",
+    dev_dependency = True,
+)
+
+# See //scala/private:extensions/dev_deps.bzl for notes on some of these repos.
+use_repo(
+    internal_dev_deps,
+    "com_github_bazelbuild_buildtools",
+    "com_github_jnr_jffi_native",
+    "com_google_guava_guava_21_0",
+    "com_google_guava_guava_21_0_with_file",
+    "com_twitter__scalding_date",
+    "org_apache_commons_commons_lang_3_5",
+    "org_apache_commons_commons_lang_3_5_without_file",
+    "org_springframework_spring_core",
+    "org_springframework_spring_tx",
+    "org_typelevel__cats_core",
+    "org_typelevel_kind_projector",
+)
+
+java_toolchains = use_extension(
+    "@rules_java//java:extensions.bzl",
+    "toolchains",
+    dev_dependency = True,
+)
+
+use_repo(
+    java_toolchains,
+    # //test/toolchains:java21_toolchain
+    "remotejdk21_linux",
+    "remotejdk21_macos",
+    "remotejdk21_win",
+    # //test/jmh:test_jmh_jdk8
+    "remote_jdk8_linux",
+    "remote_jdk8_macos",
+    "remote_jdk8_windows",
+)
+
+[
+    (
+        bazel_dep(name = name, dev_dependency = True),
+        local_path_override(module_name = name, path = path)
+    )
+    for name, path in [
+        (
+            "proto_cross_repo_boundary",
+            "test/proto_cross_repo_boundary/repo",
+        ),
+        (
+            "test_new_local_repo",
+            "third_party/test/new_local_repo",
+        ),
+        (
+            "example_external_workspace",
+            "third_party/test/example_external_workspace",
+        ),
+    ]
+]
+
+bazel_dep(
+    name = "bazel_ci_rules",
+    version = "1.0.0",
+    dev_dependency = True,
+    repo_name = "bazelci_rules",
+)
+bazel_dep(
+    name = "rules_go",
+    version = "0.53.0",
+    dev_dependency = True,
+    repo_name = "io_bazel_rules_go", # for com_github_bazelbuild_buildtools
+)
+bazel_dep(name = "gazelle", version = "0.42.0", dev_dependency = True)
+
+go_sdk = use_extension(
+    "@io_bazel_rules_go//go:extensions.bzl",
+    "go_sdk",
+    dev_dependency = True,
+)
+go_sdk.download(version = "1.24.0")
+
+go_deps = use_extension(
+    "@gazelle//:extensions.bzl",
+    "go_deps",
+    dev_dependency = True,
+)
+
+# The go_deps.module calls are inspired by the following to get the
+# com_github_bazelbuild_buildtools repo to work:
+#
+# - https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/gazelle/0.39.1/MODULE.bazel#L31-L57
+#
+# To get the latest version and hashes for each per:
+#
+# - https://go.dev/ref/mod#go-list-m
+# - https://go.dev/ref/mod#checksum-database
+#
+#   go list -m golang.org/x/tools@latest
+#   curl https://sum.golang.org/lookup/golang.org/x/tools@v0.29.0
+go_deps.module(
+    path = "golang.org/x/tools",
+    sum = "h1:BgcpHewrV5AUp2G9MebG4XPFI1E2W41zU1SaqVA9vJY=",
+    version = "v0.30.0",
+)
+
+go_deps.module(
+    path = "github.com/golang/protobuf",
+    sum = "h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=",
+    version = "v1.5.4",
+)
+use_repo(
+    go_deps,
+    "com_github_golang_protobuf",
+    "org_golang_x_tools",
+)
+
+bazel_dep(name = "rules_python", version = "1.2.0", dev_dependency = True)