Work on GN toolchain definitions and build

build/toolchain/android/BUILD.gn

+# Copyright 2013 The Chromium 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("../clang.gni")
+import("../goma.gni")
+import("../gcc_toolchain.gni")
+
+# Get the location of the Android tools in our tree.
+android_ndk_root =
+  rebase_path("//third_party/android_tools/ndk", ".", "")

[Nico, 2013/12/26 22:14:34]

Mostly unrelated: As it happens, I'm currently trying to get android to build on
mac (and eventually, it probably should build on windows too). As part of the
bringup I need to use a different ndk (the checked-in one contains linux
binaries in source control 9_9) – with gn, I'd have to change this in the .gn
file and couldn't set something like a GYP_DEFINE or (with the current
envsetup.sh) an env var, right?

+android_sdk_root =
+  rebase_path("//third_party/android_tools/sdk", ".", "")
+
+# Get the Android version of the name of the build host's architecture.
+if (build_cpu_arch == "x64") {
+  android_host_arch = "x86_64"
+} else if (build_cpu_arch == "x86") {
+  android_host_arch = "x86"
+} else {
+  assert(false, "Need Android toolchain support for your build OS.")
+}
+
+if (is_gyp) {
+  # Set the compilers for GYP to use. This logic is only relevant to GYP where
+  # there is "a" target compiler. In native GN builds, we have separate
+  # compilers for the toolchains below, any or all of which could be active in
+  # any given build.
+  if (is_clang) {
+    # Set the GYP header for all toolchains when running under Clang.
+    gyp_header = make_clang_global_settings
+  } else {
+    # Find the compiler for GYP for non-Clang Android.
+    if (cpu_arch == "x86") {
+      android_toolchain_arch = "x86-4.6"
+    } else if (cpu_arch == "arm") {
+      android_toolchain_arch = "arm-linux-androideabi-4.6"
+    } else {
+      assert(false, "Need Android toolchain support for your platform.")
+    }
+
+    android_toolchain =
+      "$android_ndk_root/toolchains/$android_toolchain_arch/prebuilt/$build_os-$android_host_arch/bin"
+
+    # This script will find the compilers for the given Android toolchain
+    # directory.
+    android_compilers = exec_script("find_android_compilers.py",
+                                    [android_toolchain], "value")
+    gyp_header =
+      "'make_global_settings': [" +
+      "['CC', '" + android_compilers[0] + "']," +
+      "['CXX', '" + android_compilers[1] + "']," +
+      "['CC.host', '" + android_compilers[2] + "']," +
+      "['CXX.host', '" + android_compilers[3] + "']," +
+      "],"
+  }
+
+  if (use_goma) {
+    # There is a TODO(yyanagisawa) in common.gypi about the make generator not
+    # supporting CC_wrapper without CC. As a result, we must add a condition
+    # when on the generator when we're not explicitly setting the variables
+    # above (which happens when gyp_header is empty at this point).
+    #
+    # GYP will interpret the file once for each generator, so we have to write
+    # this condition into the GYP file since the user could have more than one
+    # generator set.
+    if (gyp_header == "") {
+      gyp_header +=
+        "'conditions':" +
+        "['\"<(GENERATOR)\"==\"ninja\"', {" +
+        make_goma_global_settings +
+        "}],"
+    } else {
+      gyp_header += make_goma_global_settings
+    }
+  }
+}
+
+gcc_toolchain("x86") {
+  prefix = "$android_ndk_root/toolchains/x86-4.6/prebuilt/$build_os-$android_host_arch/bin/i686-linux-android-"
+  cc  = prefix + "gcc"
+  cxx = prefix + "g++"
+  ar  = prefix + "ar"
+  ld  = cxx
+
+  toolchain_cpu_arch = "x86"
+  toolchain_os = "android"
+}
+
+gcc_toolchain("arm") {
+  prefix = "$android_ndk_root/toolchains/arm-linux-androideabi-4.6/prebuilt/$build_os-$android_host_arch/bin/arm-linux-androideabi-"
+  cc  = prefix + "gcc"
+  cxx = prefix + "g++"
+  ar  = prefix + "ar"
+  ld  = cxx
+
+  toolchain_cpu_arch = "arm"
+  toolchain_os = "android"
+}