[bazel] Add potential bzlmod inclusion example

utils/bazel/MODULE.bazel

@@ -18,7 +18,7 @@ bazel_dep(name = "rules_shell", version = "0.6.1")
 bazel_dep(name = "zlib-ng", version = "2.0.7", repo_name = "llvm_zlib")
 bazel_dep(name = "zstd", version = "1.5.7", repo_name = "llvm_zstd")
 
-llvm_repos_extension = use_extension(":extensions.bzl", "llvm_repos_extension")
+llvm_repos_extension = use_extension("@llvm-raw//utils/bazel:extensions.bzl", "llvm_repos_extension")
 use_repo(
     llvm_repos_extension,
     "gmp",
@@ -34,6 +34,5 @@ use_repo(
     "vulkan_sdk",
 )
 
-llvm_configure = use_repo_rule("@llvm-raw//utils/bazel:configure.bzl", "llvm_configure")
-
-llvm_configure(name = "llvm-project")
+llvm = use_extension("@llvm-raw//utils/bazel:configure.bzl", "llvm")
+use_repo(llvm, "llvm-project")

utils/bazel/configure.bzl

@@ -206,3 +206,37 @@ llvm_configure = repository_rule(
         "targets": attr.string_list(default = DEFAULT_TARGETS),
     },
 )
+
+def _llvm_impl(mctx):
+    targets = {t: True for t in DEFAULT_TARGETS}
+    for mod in mctx.modules:
+        if not mod.is_root:
+            continue
+        if mod.tags.configure:
+            targets = {}
+        for conf in mod.tags.configure:
+            for target in conf.targets:
+                targets[target] = True
+        break
+
+    llvm_configure(
+        name = "llvm-project",
+        targets = targets.keys(),
+    )
+
+    return mctx.extension_metadata(
+        reproducible = True,
+        root_module_direct_deps = "all",
+        root_module_direct_dev_deps = [],
+    )
+
+llvm = module_extension(
+    implementation = _llvm_impl,
+    tag_classes = {
+        "configure": tag_class(
+            attrs = {
+                "targets": attr.string_list(mandatory = True),
+            },
+        ),
+    },
+)

utils/bazel/examples/bzlmod/MODULE.bazel

@@ -0,0 +1,29 @@
+# Replace with the LLVM commit you want to use.
+LLVM_COMMIT = "2d1bc9f5a212dc4c8fa14a5741af2a7a5e60ff36"
+
+# The easiest way to calculate this for a new commit is to set it to empty and
+# then run a bazel build and it will report the digest necessary to cache the
+# archive and make the build reproducible.
+LLVM_INTEGRITY = "sha256-KST3jta9pEHT0igBUxNaUoJysbefc0yBJ22UEzWcINs="
+
+bazel_dep(name = "llvm-raw")
+archive_override(
+    module_name = "llvm-raw",
+    integrity = LLVM_INTEGRITY,
+    patch_cmds = [
+        "cat utils/bazel/MODULE.bazel | grep -v '\"llvm-raw\"' | sed 's|llvm-project-overlay|llvm-raw|g' > MODULE.bazel",
+    ],
+    strip_prefix = "llvm-project-" + LLVM_COMMIT,
+    urls = ["https://github.com/llvm/llvm-project/archive/{commit}.tar.gz".format(commit = LLVM_COMMIT)],
+)
+
+llvm = use_extension("@llvm-raw//utils/bazel:configure.bzl", "llvm")
+
+# Optionally configure LLVM targets here
+# llvm.configure(
+#     targets = [
+#         "X86",
+#         ...
+#     ],
+# )
+use_repo(llvm, "llvm-project")