Add aspect_rules_lint Python formatting with Ruff

.github/workflows/licence-checker.yml

@@ -22,5 +22,7 @@ jobs:
       with:
         # TODO: Check on Python 3.8 too
         python-version: 3.6
+    - name: Check formatting with Ruff
+      run: bazel run :format.check
     - name: Run Licence Checker
       run: bazel run //:licence-check

BUILD

@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 load("//rules:rules.bzl", "licence_check")
+load("@aspect_rules_lint//format:defs.bzl", "format_multirun")
 
 licence_check(
     name = "licence-check",
@@ -13,3 +14,18 @@ licence_check(
     SPDX-License-Identifier: Apache-2.0
     """,
 )
+
+alias(
+    name = "ruff",
+    actual = select({
+        "@bazel_tools//src/conditions:linux_x86_64": "@ruff_x86_64-unknown-linux-gnu//:ruff",
+        "@bazel_tools//src/conditions:linux_aarch64": "@ruff_aarch64-unknown-linux-gnu//:ruff",
+        "@bazel_tools//src/conditions:darwin_arm64": "@ruff_aarch64-apple-darwin//:ruff",
+        "@bazel_tools//src/conditions:darwin_x86_64": "@ruff_x86_64-apple-darwin//:ruff",
+    }),
+)
+
+format_multirun(
+    name = "format",
+    python = ":ruff",
+)

WORKSPACE

@@ -12,3 +12,29 @@ lowrisc_misc_linters_dependencies()
 
 load("//rules:pip.bzl", "lowrisc_misc_linters_pip_dependencies")
 lowrisc_misc_linters_pip_dependencies()
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+http_archive(
+    name = "aspect_rules_lint",
+    sha256 = "6da562afb6e328757eb29f3ad044e273317371139d245eac0a74b60173d36025",
+    strip_prefix = "rules_lint-1.0.0-rc3",
+    url = "https://github.com/aspect-build/rules_lint/releases/download/v1.0.0-rc3/rules_lint-v1.0.0-rc3.tar.gz",
+)
+
+# aspect_rules_lint depends on aspect_bazel_lib. Either 1.x or 2.x works.
+http_archive(
+    name = "aspect_bazel_lib",
+    sha256 = "6d758a8f646ecee7a3e294fbe4386daafbe0e5966723009c290d493f227c390b",
+    strip_prefix = "bazel-lib-2.7.7",
+    url = "https://github.com/aspect-build/bazel-lib/releases/download/v2.7.7/bazel-lib-v2.7.7.tar.gz",
+)
+load("@aspect_bazel_lib//lib:repositories.bzl", "aspect_bazel_lib_dependencies")
+
+# aspect_bazel_lib depends on bazel_skylib
+aspect_bazel_lib_dependencies()
+
+load("@aspect_rules_lint//format:repositories.bzl", "rules_lint_dependencies")
+rules_lint_dependencies()
+
+load("@aspect_rules_lint//lint:ruff.bzl", "fetch_ruff")
+fetch_ruff()