# Copyright 2018 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/clang/clang.gni")
import("//build/config/compiler.gni")
import("//build/config/sysroot.gni")
import("//build/fidl/toolchain.gni")

default_rust_sysroot =
    rebase_path("//prebuilt/third_party/rust/${host_platform}", root_build_dir)

default_rustc_tool_dir = "//prebuilt/third_party/rust/${host_platform}/bin"
default_rustc_prefix = rebase_path(default_rustc_tool_dir, root_build_dir)

_rustc_version = read_file(
        "//prebuilt/third_party/rust/${host_platform}/.versions/rust.cipd_version",
        "json")
default_rustc_version_string = _rustc_version.instance_id

declare_args() {
  # Sets a custom base directory for `rustc` and `cargo`.
  # This can be used to test custom Rust toolchains.
  rustc_prefix = default_rustc_prefix

  # This is a string identifying the particular toolchain version in use.  Its
  # only purpose is to be unique enough that it changes when switching to a new
  # toolchain, so that recompilations with the new compiler can be triggered.
  #
  # When using the prebuilt, this is ignored and the CIPD instance ID of the
  # prebuilt is used.
  rustc_version_string = default_rustc_version_string

  # Human-readable identifier for the toolchain version.
  #
  # TODO(tmandry): Make this the same repo/revision info from `rustc --version`.
  # e.g., clang_version_description = read_file("$_rustc_lib_dir/VERSION")
  rustc_version_description = ""

  # Sets a custom base directory for where rust tooling
  # looks for the standard library
  rust_sysroot = default_rust_sysroot

  # Sets the default LTO type for rustc bulids.
  rust_lto = ""

  # Sets the fuchsia toolchain target triple suffix (after arch)
  rust_toolchain_triple_suffix = "fuchsia"

  # Sets the maximum lint level.
  # "deny" will make all warnings into errors, "warn" preserves them as warnings, and "allow" will
  # ignore warnings.
  rust_cap_lints = "deny"

  # Overrides the optimization level for all Rust builds, regardless of
  # debug/release flags or the `force_opt` arg to the rustc_ templates.
  # Valid values are 0-3, o, and z.
  rust_override_opt = ""

  # Overrides the LTO setting for all Rust builds, regardless of
  # debug/release flags or the `with_lto` arg to the rustc_ templates.
  # Valid values are "none", "thin", and "fat".
  rust_override_lto = ""
}

if (rustc_prefix == default_rustc_prefix &&
    rustc_version_string != default_rustc_version_string) {
  # You almost never want to set this when using a prebuilt, it could result in
  # failing to rebuild when the prebuilt updates.
  print(
      "WARNING: Using prebuilt toolchain, but rustc_version_string is set! Toolchain updates won't be detected.")
}

# rustc_tool_dir: Like rustc_prefix, but an absolute path.
if (rustc_prefix == default_rustc_prefix) {
  rustc_tool_dir = default_rustc_tool_dir
} else {
  rustc_tool_dir = rebase_path(rustc_prefix, "", root_build_dir)
}

if (is_fuchsia) {
  rust_panic = "abort"
} else {
  # Always use panic=unwind on host, or proc macros won't work.
  rust_panic = "unwind"
}

assert(
    current_os == "mac" || current_os == "linux" || current_os == "fuchsia" ||
        (current_os == "unknown" && current_cpu == "wasm32") ||
        current_os == "win",
    "current_os was neither mac, linux, unknown, nor fuchsia")
assert(
    current_cpu == "x64" || current_cpu == "arm64" || current_cpu == "wasm32")
if (current_os == "mac") {
  _suffix = "apple-darwin"
} else if (current_os == "linux") {
  _suffix = "unknown-linux-gnu"
} else if (current_os == "win") {
  _suffix = "windows-msvc"
} else if (current_os == "fuchsia") {
  _suffix = rust_toolchain_triple_suffix
}
if (current_cpu == "x64") {
  rust_target = "x86_64-${_suffix}"
} else if (current_cpu == "arm64") {
  rust_target = "aarch64-${_suffix}"
} else if (current_cpu == "wasm32" && current_os == "unknown") {
  rust_target = "wasm32-unknown-unknown"
}