build/toolchain/basic_toolchain.gni

# Copyright 2020 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/toolchain/default_tools.gni")

# Define a basic GN toolchain() instance that only has the "stamp" and "copy"
# tools. Use this for toolchains that will only have action() targets.
#
# Parameters:
#   expected_label: Optional
#     If provided, this template will assert that the full toolchain label
#     matches this value. This is useful when the definition should match
#     a global variable (e.g. go_toolchain or dart_toolchain).
#     Type: GN label
#
#  toolchain_args: Optional
#     A scope of extra toolchain_args keys for this toolchain instance.
#
# NOTE: This also ensures this defines the global `toolchain_variant.base`
# variable, allowing BUILDCONFIG.gn to detect that this is not the default
# toolchain (see the definition of in_default_toolchain in that file for
# more details).
template("basic_toolchain") {
  if (current_toolchain == default_toolchain) {
    # This needs to be passed to basic toolchains because they can
    # include configs() that depend on it.
    _pass_through_clang_toolchain_info = clang_toolchain_info

    # Basic toolchains should only be expanded once in the default toolchain.
    toolchain(target_name) {
      tool("stamp") {
        command = stamp_command
        description = stamp_description
      }
      tool("copy") {
        command = copy_command
        description = copy_description
      }
      toolchain_args = {
        if (defined(invoker.toolchain_args)) {
          forward_variables_from(invoker.toolchain_args, "*")
        }
        toolchain_variant = {
        }
        toolchain_variant = {
          # This is a "basic" toolchain
          is_basic = true
          base = get_label_info(":$target_name", "label_no_toolchain")
          if (defined(invoker.expected_label)) {
            assert(
                base == invoker.expected_label,
                "Invalid toolchain label $base, expected ${invoker.expected_label}")
          }
        }
        clang_toolchain_info = {
        }
        clang_toolchain_info = _pass_through_clang_toolchain_info

        # LINT.IfChange(in_default_toolchain)
        in_default_toolchain = false

        # LINT.ThenChange(//build/config/BUILDCONFIG.gn:in_default_toolchain)
      }
    }
  } else {
    not_needed("*")
    not_needed(invoker, "*")
  }
}