[bazel] Enable bzlmod in hybrid mode

This commit adds a `MODULE.bazel` file and enables the bzlmod feature,
but actually continues to use the existing `WORKSPACE` dependency
management by moving to `WORKSPACE.bzlmod`.

Dependencies can be gradually migrated from `WORKSPACE` to
`MODULE.bazel`.

Signed-off-by: James Wainwright <[email protected]>

.bazelrc

@@ -2,8 +2,8 @@
 # Licensed under the Apache License, Version 2.0, see LICENSE for details.
 # SPDX-License-Identifier: Apache-2.0
 
-# Opt-out of bzlmod for now and continue to use `WORKSPACE`.
-common --noenable_bzlmod
+# Enable bzlmod using both `MODULE.bazel` and `WORKSPACE.bzlmod`.
+common --enable_bzlmod
 
 # https://docs.opentitan.org/doc/rm/c_cpp_coding_style/#cxx-version specifies
 build --action_env=BAZEL_CXXOPTS="-std=gnu++14"

.gitattributes

@@ -26,3 +26,6 @@ sw/**/*.md  doc
 sw/**/*.svg doc
 sw/**/*.jpg doc
 sw/**/*.png doc
+
+# Generated lock files
+MODULE.bazel.lock linguist-generated=true

BUILD.bazel

@@ -5,7 +5,7 @@
 package(default_visibility = ["//visibility:public"])
 
 exports_files([
-    "WORKSPACE",
+    "WORKSPACE.bzlmod",
     "python-requirements.txt",
     "tool_requirements.py",
 ])

MODULE.bazel

@@ -0,0 +1,5 @@
+# Copyright lowRISC contributors (OpenTitan project).
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+
+module(name = "lowrisc_opentitan")

quality/BUILD.bazel

@@ -79,7 +79,7 @@ licence_test(
     Licensed under the Apache License, Version 2.0, see LICENSE for details.
     SPDX-License-Identifier: Apache-2.0
     """,
-    workspace = "//:WORKSPACE",
+    workspace = "//:WORKSPACE.bzlmod",
 )
 
 format_exclude = [
@@ -99,7 +99,7 @@ clang_format_test(
     name = "clang_format_check",
     exclude_patterns = format_exclude,
     mode = "diff",
-    workspace = "//:WORKSPACE",
+    workspace = "//:WORKSPACE.bzlmod",
 )
 
 clang_format_check(
@@ -141,7 +141,7 @@ test_suite(
 )
 
 buildifier_exclude = [
-    "./WORKSPACE",  # Prevent Buildifier from inserting unnecessary newlines.
+    "./WORKSPACE.bzlmod",  # Prevent Buildifier from inserting unnecessary newlines.
     "./**/vendor/**",
     "./build/**",
     "./third_party/rust/crates/crates.bzl",  # Autogenerated by cargo-raze
@@ -159,7 +159,7 @@ buildifier_test(
     mode = "diff",
     no_sandbox = True,
     verbose = True,
-    workspace = "//:WORKSPACE",
+    workspace = "//:WORKSPACE.bzlmod",
 )
 
 # TODO(cfrantz): Find a way to keep this list of rust targets synchronized
@@ -194,7 +194,7 @@ RUST_TARGETS = [
 rustfmt_test(
     name = "rustfmt_check",
     exclude_patterns = format_exclude,
-    workspace = "//:WORKSPACE",
+    workspace = "//:WORKSPACE.bzlmod",
 )
 
 rustfmt_fix(
@@ -210,7 +210,7 @@ sh_test(
     name = "shellcheck_check",
     srcs = ["//util/sh/scripts:run-shellcheck.sh"],
     data = [
-        "//:WORKSPACE",
+        "//:WORKSPACE.bzlmod",
         "@shellcheck",
     ],
     env = {

rules/repo.bzl

@@ -79,7 +79,7 @@ bare_repository = repository_rule(
             doc = "Script to create symlink trees for the `local` case.",
         ),
         "workspace": attr.label(
-            default = Label("//:WORKSPACE"),
+            default = Label("//:WORKSPACE.bzlmod"),
             allow_single_file = True,
             doc = "Root workspace.",
         ),

rules/scripts/clang_format.template.sh

@@ -16,7 +16,7 @@ elif [[ ! -z "${BUILD_WORKSPACE_DIRECTORY+is_set}" ]]; then
     cd ${BUILD_WORKSPACE_DIRECTORY} || exit 1
 else
     echo "Neither WORKSPACE nor BUILD_WORKSPACE_DIRECTORY were set."
-    echo "If this is a test rule, add 'workspace = \"//:WORKSPACE\"' to your rule."
+    echo "If this is a test rule, add 'workspace = \"//:WORKSPACE.bzlmod\"' to your rule."
     exit 1
 fi
 

rules/scripts/rustfmt.template.sh

@@ -16,7 +16,7 @@ elif [[ -n "${BUILD_WORKSPACE_DIRECTORY+is_set}" ]]; then
     cd "${BUILD_WORKSPACE_DIRECTORY}" || exit 1
 else
     echo "Neither WORKSPACE nor BUILD_WORKSPACE_DIRECTORY were set."
-    echo "If this is a test rule, add 'workspace = \"//:WORKSPACE\"' to your rule."
+    echo "If this is a test rule, add 'workspace = \"//:WORKSPACE.bzlmod\"' to your rule."
     exit 1
 fi
 

util/sh/scripts/run-shellcheck.sh

@@ -6,12 +6,12 @@
 set -e
 
 # Escape the sandbox when running under `bazel test`. This script assumes that
-# when it's invoked by Bazel, the Bazel target will depend on `//:WORKSPACE`.
+# when it's invoked by Bazel, the Bazel target will depend on `//:WORKSPACE.bzlmod`.
 # This assumption enables us to infer that we're running in the sandbox when we
-# see a symlink named "WORKSPACE".
-if [[ -L WORKSPACE ]]; then
+# see a symlink named "WORKSPACE.bzlmod".
+if [[ -L WORKSPACE.bzlmod ]]; then
     SHELLCHECK="$(realpath "${SHELLCHECK}")"
-    REPO_TOP="$(dirname "$(realpath WORKSPACE)")"
+    REPO_TOP="$(dirname "$(realpath WORKSPACE.bzlmod)")"
     cd "${REPO_TOP}"
 else
     REPO_TOP="$(git rev-parse --show-toplevel)"