build/sdk/idk_subbuilds.gni

# Copyright 2023 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/config/compiler.gni")
import("//build/config/fuchsia/platform_version.gni")
import("//build/sdk/config.gni")
import("//build/subbuild.gni")
import("//sdk/config.gni")

# Calling this template generates a set of action() targets, each one building
# the atoms of a given sdk_collection() for a specific CPU architecture and API
# levels. This is used by the idk() template.
#
# The generated actions are named as follows:
#
#    ${target_name}-${cpu}
#        For the default API level, and each supported ${cpu}
#        Uses ${root_build_dir}/${subbuild_prefix}-${cpu} as its build directory.
#
#    ${target_name}-api${api_level}-${cpu}
#        For individual API levels and cpu values.
#        Uses ${root_build_dir}/${subbuild_prefix}-api${api_level}-${cpu} as
#        its build directory.
#
# Each action will depend on sdk_collection_label as well as //sdk:idk_build_tools.
#
# Note that this does not define a top-level group() target that depends on all of
# them. Instead, users like the idk() template should pick the sub-build targets
# they need directly.
#
# Args:
#    sdk_collection_label  (required)
#      [GN Label] Label of sdk_collection() target to generate sub-builds for.
#
#    subbuild_prefix  (optional)
#      [string] A name prefix for all sub-build directories. Default is
#          "idk_subbuild.<name>"  where <name> is the name of the sdk_collection_label
#          target. This is useful to differentiatte idk_subbuilds() instances that
#          reference collections with the same name, but different directories
#          (e.g. `//sdk:core` and `//vendor/acme/sdk:core`).
#
#   sdk_collection_name (optional)
#     The name of the collection specified by `sdk_collection_label`.
#     Should match the name of the collection if it is overridden.
#     Defaults to the name portion of the `sdk_collection_label`.
#
template("idk_subbuilds") {
  main_target_name = target_name

  if (defined(invoker.subbuild_prefix)) {
    subbuild_prefix = invoker.subbuild_prefix
  } else {
    subbuild_prefix =
        "idk_subbuild." + get_label_info(invoker.sdk_collection_label, "name")
  }

  _api_levels = platform_version.idk_buildable_api_levels
  _target_cpus = idk_target_cpus_default

  if (defined(invoker.sdk_collection_name)) {
    _sdk_collection_dir_name = invoker.sdk_collection_name
  } else {
    _sdk_collection_dir_name =
        get_label_info(invoker.sdk_collection_label, "name")
  }

  # First, define subbuild targets for the default API level.
  foreach(target_cpu, _target_cpus) {
    _subbuild_target = "${main_target_name}-${target_cpu}"
    _subbuild_dir_prefix = "${subbuild_prefix}-${target_cpu}"

    subbuild(_subbuild_target) {
      target = invoker.sdk_collection_label
      use_idk_tools_only = true

      _collection_dir_manifest =
          "/sdk/exported/${_sdk_collection_dir_name}/meta/manifest.json"
      outputs = [ _collection_dir_manifest ]

      api_level_path = "/sdk/exported/${_sdk_collection_dir_name}/api_level"

      target_cpu = target_cpu
      api_level = "PLATFORM"
      build_dir_prefix = _subbuild_dir_prefix

      # Each subbuild depends on the `sdk_collection` in the main build, so
      # that when a change happens that would cause the `sdk_collection` to be
      # rebuilt, that also triggers the subbuilds to be rerun.
      extra_deps = [ invoker.sdk_collection_label ]

      forward_variables_from(invoker,
                             [
                               "testonly",
                               "visibility",
                             ])
    }
  }

  # Now, define subbuild targets for all individual API levels and CPUs.
  foreach(api_level, _api_levels) {
    foreach(target_cpu, _target_cpus) {
      _subbuild_target = "${main_target_name}-api${api_level}-${target_cpu}"
      _subbuild_dir_prefix = "${subbuild_prefix}-api${api_level}-${target_cpu}"

      subbuild(_subbuild_target) {
        target = invoker.sdk_collection_label
        use_idk_tools_only = true

        _collection_dir_manifest =
            "/sdk/exported/${_sdk_collection_dir_name}/meta/manifest.json"
        outputs = [ _collection_dir_manifest ]

        api_level_path = "/sdk/exported/${_sdk_collection_dir_name}/api_level"

        target_cpu = target_cpu
        api_level = "$api_level"
        build_dir_prefix = _subbuild_dir_prefix

        # Each subbuild depends on the `sdk_collection` in the main build, so
        # that when a change happens that would cause the `sdk_collection` to be
        # rebuilt, that also triggers the subbuilds to be rerun.
        extra_deps = [ invoker.sdk_collection_label ]

        forward_variables_from(invoker,
                               [
                                 "testonly",
                                 "visibility",
                               ])
      }
    }
  }
}