# 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") {
  # The line below is required, otherwise 'gn gen' will complain with an error
  # (i.e. 'You set the variable "invoker" here and it was unused before it went
  # out of scope') if the template is called without any arguments.
  not_needed([ "invoker" ])

  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 = {
        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}")
        }
      }
    }
  }
}