Fix BCR build issues and add Bazel 9 support

Motivation: These changes are required for P4Runtime to build
successfully for downstream users who depend on it via the BCR.
Issues were discovered while upstreaming P4Runtime v1.5.0 to the BCR
(bazelbuild/bazel-central-registry#7594) and when adding Bazel 9
support.

Dependency updates:
- Upgrade googleapis and replace the switched_rules extension with the
  new per-language modules (googleapis-cc, googleapis-go,
  googleapis-python, googleapis-grpc-cc). The old switched_rules
  extension only processes use_languages() calls from the root module,
  which breaks BCR presubmit and downstream users who don't call it
  themselves.
- Upgrade grpc 1.68.0 -> 1.76.0, protobuf 29.1 -> 33.5,
  bazel_skylib 1.7.1 -> 1.9.0, rules_go 0.59.0 -> 0.60.0,
  re2 -> 2025-11-05.bcr.1.
- Remove rules_proto and gazelle deps (no longer needed).
- Load proto_library from @protobuf//bazel:proto_library.bzl instead
  of the deprecated @rules_proto//proto:defs.bzl.

CI coverage gap fix:
- Our example project in bazel/example/using-bzlmod only exercised some
  @p4runtime targets transitively, allowing build issues to slip through.
- Fix: run bazel build @p4runtime//... from the example workspace.

Bazel 9 support:
- Remove the <9.0.0 upper bound from bazel_compatibility.
- Update .bazelversion to 9.0.0.
- Add --incompatible_autoload_externally=+cc_library,+cc_binary to
  .bazelrc files. Bazel 9 removed native C++ rules from the global
  namespace; this flag restores the autoload. It is a no-op on Bazel
  7/8. (Workaround for two gRPC 1.76.0 bundled files that still use
  native.cc_binary / native.cc_library; can be dropped once a fixed
  gRPC BCR release ships.)
- Update CI to test on Bazel 7.x and 9.x.

Signed-off-by: Steffen Smolka <steffen.smolka@gmail.com>

Author: smolkaj

.bazelignore

@@ -1,2 +1,8 @@
 # Exclude bazel sub-projects so `bazel build //...` works.
 bazel/example
+
+# Exclude Bazel output symlinks to avoid gnarly errors.
+bazel-bin
+bazel-out
+bazel-testlogs
+bazel-p4runtime

.bazelrc

@@ -2,6 +2,17 @@
 common --enable_bzlmod
 common --noenable_workspace
 
+# In Bazel 9, native C++ rules are no longer injected into the global namespace
+# by default.  Two files in grpc 1.76.0 still use native.cc_*:
+#   bazel/cython_library.bzl      (native.cc_binary)
+#   third_party/address_sorting/address_sorting.bzl  (native.cc_library)
+# Restore the autoload until grpc 1.76.0.bcr.2 lands.  No-op on Bazel 7/8.
+build --incompatible_autoload_externally=+cc_library,+cc_binary
+
 # Use C++17 (required for recent gRPC versions).
 build --cxxopt=-std=c++17
 build --host_cxxopt=-std=c++17
+
+# Extra flags needed to build on macOS.
+build --repo_env=CC=/usr/bin/clang
+build --macos_minimum_os=10.13

.bazelversion

@@ -1 +1 @@
-8.5.1
+9.0.0

.github/workflows/bazel-build.yml

@@ -21,8 +21,7 @@ jobs:
         # We trust that things also work for versions in the middle.
         os: [ubuntu-22.04, ubuntu-latest]
         # See Bazelisk README for legal values.
-        # TODO(#582): Add back "latest" once we support Bazel 9.
-        bazel_version: [7.x, 8.x]
+        bazel_version: [7.x, latest]
       # Don't abort other runs when one of them fails, to ease debugging.
       fail-fast: false
 
@@ -62,10 +61,12 @@ jobs:
         format: X
 
     - name: Build proto/
-      run: cd proto && bazel build //... && bazel test //...
+      run: bazel build //... && bazel test //...
 
     - name: Build bazel/example/using-bzlmod/
-      run: cd bazel/example/using-bzlmod && bazel build //...
+      run: |
+        cd bazel/example/using-bzlmod
+        bazel build @p4runtime//... //...
 
     - name: Save end time
       # Always save the end time so we can calculate the build duration.

MODULE.bazel

@@ -1,32 +1,25 @@
 module(
     name = "p4runtime",
-    # TODO(#582): Remove upper bound once we support Bazel 9.x.
-    bazel_compatibility = [">=7.0.0", "<9.0.0"],
     # Fill in concrete versions only on release branches/in the BCR.
     version = "head",
+    bazel_compatibility = [">=7.0.0"],
 )
 
-bazel_dep(name = "bazel_skylib", version = "1.7.1")
-bazel_dep(name = "rules_cc", version = "0.2.16")
-bazel_dep(name = "googleapis", version = "0.0.0-20240819-fe8ba054a")
-bazel_dep(name = "grpc", version = "1.68.0")
-bazel_dep(name = "protobuf", version = "29.1")
+bazel_dep(name = "bazel_skylib", version = "1.9.0")
+bazel_dep(name = "googleapis", version = "0.0.0-20260130-c0fcb356")
+bazel_dep(name = "googleapis-cc", version = "1.0.0")
+bazel_dep(name = "googleapis-go", version = "1.0.0")
+bazel_dep(name = "googleapis-python", version = "1.0.0")
+bazel_dep(name = "googleapis-grpc-cc", version = "1.0.0")
+bazel_dep(name = "grpc", version = "1.76.0")
+bazel_dep(name = "protobuf", version = "33.5")
+bazel_dep(name = "re2", version = "2025-11-05.bcr.1")
+bazel_dep(name = "rules_cc", version = "0.2.17")
+bazel_dep(name = "rules_go", version = "0.60.0")
 bazel_dep(name = "rules_license", version = "1.0.0")
-bazel_dep(name = "rules_proto", version = "7.0.2")
-bazel_dep(name = "rules_go", version = "0.59.0")
-bazel_dep(name = "gazelle", version = "0.45.0")
-
-switched_rules = use_extension("@googleapis//:extensions.bzl", "switched_rules")
-switched_rules.use_languages(
-    cc = True,
-    go = True,
-    grpc = True,
-    python = True,
-)
-use_repo(switched_rules, googleapis_imports = "com_google_googleapis_imports")
 
 # Including this allows us to auto-format all Bazel files by running
 # ```
 # bazel run -- @buildifier_prebuilt//:buildifier -lint=fix -r $(bazel info workspace)
 # ```
-bazel_dep(name = "buildifier_prebuilt", version = "8.2.1.1", dev_dependency = True)
+bazel_dep(name = "buildifier_prebuilt", version = "8.2.1.2", dev_dependency = True)

bazel/example/using-bzlmod/.bazelrc

@@ -2,6 +2,13 @@
 common --enable_bzlmod
 common --noenable_workspace
 
+# In Bazel 9, native C++ rules are no longer injected into the global namespace
+# by default.  Two files in grpc 1.76.0 still use native.cc_*:
+#   bazel/cython_library.bzl      (native.cc_binary)
+#   third_party/address_sorting/address_sorting.bzl  (native.cc_library)
+# Restore the autoload until grpc 1.76.0.bcr.2 lands.  No-op on Bazel 7/8.
+build --incompatible_autoload_externally=+cc_library,+cc_binary
+
 # Use C++17 (required for recent gRPC versions).
 build --cxxopt=-std=c++17
 build --host_cxxopt=-std=c++17

bazel/example/using-bzlmod/MODULE.bazel

@@ -1,6 +1,6 @@
 bazel_dep(name = "p4runtime")
-bazel_dep(name = "protobuf", version = "29.1")
-bazel_dep(name = "rules_cc", version = "0.2.16")
+bazel_dep(name = "protobuf", version = "33.5")
+bazel_dep(name = "rules_cc", version = "0.2.17")
 
 # In your own project, you will likely want to use `git_override` instead
 # of `local_repository` to load p4runtime.

proto/p4/config/v1/BUILD.bazel

@@ -1,8 +1,8 @@
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@grpc//bazel:python_rules.bzl", "py_proto_library")
 load("@protobuf//bazel:cc_proto_library.bzl", "cc_proto_library")
+load("@protobuf//bazel:proto_library.bzl", "proto_library")
 load("@rules_go//proto:def.bzl", "go_proto_library")
-load("@rules_proto//proto:defs.bzl", "proto_library")
 
 package(
     default_visibility = ["//visibility:public"],

proto/p4/v1/BUILD.bazel

@@ -2,8 +2,8 @@ load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@grpc//bazel:cc_grpc_library.bzl", "cc_grpc_library")
 load("@grpc//bazel:python_rules.bzl", "py_grpc_library", "py_proto_library")
 load("@protobuf//bazel:cc_proto_library.bzl", "cc_proto_library")
+load("@protobuf//bazel:proto_library.bzl", "proto_library")
 load("@rules_go//proto:def.bzl", "go_proto_library")
-load("@rules_proto//proto:defs.bzl", "proto_library")
 
 package(
     default_visibility = ["//visibility:public"],