enabling auto-publishing to BCR (uber#109)

This adds the template files so that the Publish to BCR app can publish
new releases of this repo to Bazel Central Repository as Bazel modules.

.bazelignore

@@ -0,0 +1 @@
+examples

.bcr/metadata.template.json

@@ -0,0 +1,20 @@
+{
+    "homepage": "https://github.com/uber/hermetic_cc_toolchain",
+    "maintainers": [
+        {
+            "email": "[email protected]",
+            "github": "sywhang",
+            "name": "Sung Yoon Whang"
+        },
+        {
+            "email": "[email protected]",
+            "github": "linzhp",
+            "name": "Zhongpeng Lin"
+        }
+    ],
+    "repository": [
+      "github:uber/hermetic_cc_toolchain"
+    ],
+    "versions": [],
+    "yanked_versions": {}
+  }

.bcr/presubmit.yml

@@ -0,0 +1,10 @@
+bcr_test_module:
+  module_path: "examples/bzlmod"
+  matrix:
+    platform: ["debian11", "macos", "macos_arm64", "ubuntu2004_arm64"]
+  tasks:
+    run_tests:
+      name: "Run test module"
+      platform: ${{ platform }}
+      test_targets:
+        - "//..."

.bcr/source.template.json

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

.buildkite/pipeline.yml

@@ -23,6 +23,8 @@ steps:
   #   command: apt-get update && apt-get install --no-install-recommends -y wine64 python3 ca-certificates && ci/zig-utils
   - label: "Test rules_cc example"
     command: ci/prepare_git && ci/test_example rules_cc
+  - label: "Test bzlmod example"
+    command: ci/prepare_git && ci/test_example bzlmod
   - label: "mod-tidy and update-repos"
     command: tools/mod-tidy && git diff --exit-code
 agents:

.gitignore

@@ -6,3 +6,4 @@
 /bazel-out
 /bazel-testlogs
 /bazel-x
+/examples/bzlmod/bazel-*

examples/bzlmod/.bazelrc

@@ -0,0 +1,11 @@
+common --enable_bzlmod
+test --sandbox_default_allow_network=false
+test --test_output=errors
+
+build --verbose_failures
+build --worker_sandboxing
+
+build --experimental_reuse_sandbox_directories
+build --incompatible_enable_cc_toolchain_resolution
+build --action_env BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
+build --experimental_output_directory_naming_scheme=diff_against_baseline

examples/bzlmod/BUILD.bazel

@@ -0,0 +1,32 @@
+# Copyright 2023 Uber Technologies, Inc.
+# Licensed under the MIT License
+
+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library", "go_test")
+load("@hermetic_cc_toolchain//rules:platform.bzl", "platform_binary", "platform_test")
+
+go_library(
+    name = "cgo_lib",
+    srcs = ["cgo.go"],
+    cgo = True,
+    importpath = "github.com/uber/hermetic_cc_toolchain/test/bzlmod",
+    visibility = ["//visibility:private"],
+)
+
+go_test(
+    name = "cgo_test",
+    srcs = ["cgo_test.go"],
+    embed = [":cgo_lib"],
+)
+
+go_binary(
+    name = "cgo",
+    embed = [":cgo_lib"],
+    gc_linkopts = select({
+        "@platforms//os:macos": [
+            "-w",  # https://github.com/ziglang/zig/issues/15439
+            "-buildmode=pie",  # https://github.com/ziglang/zig/issues/15438
+        ],
+        "//conditions:default": [],
+    }),
+    visibility = ["//visibility:public"],
+)

examples/bzlmod/MODULE.bazel

@@ -0,0 +1,31 @@
+module(
+    name = "hermetic_cc_toolchain_bcr_tests",
+    version = "0.1.0",
+)
+
+bazel_dep(
+    name = "hermetic_cc_toolchain",
+    version = "",
+)
+local_path_override(
+    module_name = "hermetic_cc_toolchain",
+    path = "../..",
+)
+
+toolchains = use_extension("@hermetic_cc_toolchain//toolchain:ext.bzl", "toolchains")
+use_repo(toolchains, "zig_sdk")
+
+register_toolchains(
+    "@zig_sdk//toolchain:linux_amd64_gnu.2.31",
+    "@zig_sdk//toolchain:linux_arm64_gnu.2.31",
+    "@zig_sdk//toolchain:darwin_amd64",
+    "@zig_sdk//toolchain:darwin_arm64",
+    "@zig_sdk//toolchain:windows_amd64",
+    "@zig_sdk//toolchain:windows_arm64",
+)
+
+bazel_dep(
+    name = "rules_go",
+    version = "0.41.0",
+    repo_name = "io_bazel_rules_go",
+)