Convert api_surfaces to a custom repository

b runs using --package_path that points to out/soong/workspace (e.g.).
However, local_repository evaluates relative to workspace root
($ANDROID_TOP/build/bazel/api_surfaces) and not relative to package path
($ANDROID_TOP/out/soong/workspace/build/bazel/api_surfaces). Since the
aliases to stubs are generated using bp2build, none of them were
actually available in the external repo.

To fix this, use a custom repository rule that symlinks the contents of
out/soong/workspace/build/bazel/api_surfaces/... into external. Once the
BUILD files are ready to be checked-in, this custom repository rule
should be replaced with local_repository

Test: b cquery @api_surfaces//... (with aosp/2475621)
Change-Id: I6b7f4af2fd191e495b07934c04bc63b9dccb8cf7

2 files changed, 30 insertions, 4 deletions

diff --git a/bazel.WORKSPACE b/bazel.WORKSPACE
index 78485165..e5ec7340 100644
--- a/bazel.WORKSPACE
+++ b/bazel.WORKSPACE
@@ -36,10 +36,10 @@ env_repository(
 )
 
 # This repository is a containter for API surface stub libraries.
-local_repository(
-    name = "api_surfaces",
-    path = "build/bazel/api_surfaces",
-)
+load("//build/bazel/rules:api_surfaces_injection.bzl", "api_surfaces_repository")
+
+# TODO: Once BUILD files for stubs are checked-in, this should be converted to a local_repository.
+api_surfaces_repository(name = "api_surfaces")
 
 load("//build/bazel_common_rules/workspace:external.bzl", "import_external_repositories")
 
diff --git a/rules/api_surfaces_injection.bzl b/rules/api_surfaces_injection.bzl
new file mode 100644
index 00000000..9d10e9ad
--- /dev/null
+++ b/rules/api_surfaces_injection.bzl
@@ -0,0 +1,26 @@
+# Copyright (C) 2023 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load("//build/bazel/rules/apis:api_surface.bzl", "ALL_API_SURFACES")
+
+def _impl(rctx):
+    rctx.file("WORKSPACE", "")
+    synthetic_build_dir = str(rctx.path(Label("//:BUILD")).dirname)
+    api_surfaces_dir = synthetic_build_dir + "/build/bazel/api_surfaces"
+    for api_surface in ALL_API_SURFACES:
+        rctx.symlink(api_surfaces_dir + "/" + api_surface, api_surface)
+
+api_surfaces_repository = repository_rule(
+    implementation = _impl,
+)