[ios] Partially decouple iOS and macOS GN configuration.

build/config/ios/BUILD.gn

 # Copyright 2014 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("//build/config/ios/ios_sdk.gni")
 import("//build/config/sysroot.gni")
 import("//build/toolchain/toolchain.gni")
 
 declare_args() {
   # Enabling this option makes clang compile to an intermediate
   # representation ("bitcode"), and not to native code. This is preferred
   # when including WebRTC in the apps that will be sent to Apple's App Store
   # and mandatory for the apps that run on watchOS or tvOS.
   # The option only works when building with Xcode (use_xcode_clang = true).
   # Mimicking how Xcode handles it, the production builds (is_debug = false)
   # get real bitcode sections added, while the debug builds (is_debug = true)
   # only get bitcode-section "markers" added in them.
   # NOTE: This option is ignored when building versions for the iOS simulator,
   # where a part of libvpx is compiled from the assembly code written using
   # Intel assembly syntax; Yasm / Nasm do not support emitting bitcode parts.
   # That is not a limitation for now as Xcode mandates the presence of bitcode
   # only when building bitcode-enabled projects for real devices (ARM CPUs).
   enable_ios_bitcode = false
 }
 
+# This is included by reference in the //build/config/compiler config that
+# is applied to all targets. It is here to separate out the logic.
+config("compiler") {
+  # These flags are shared between the C compiler and linker.
+  common_ios_flags = []
+
+  # CPU architecture.
+  if (current_cpu == "x64") {
+    common_ios_flags += [
+      "-arch",
+      "x86_64",
+    ]
+  } else if (current_cpu == "x86") {
+    common_ios_flags += [
+      "-arch",
+      "i386",
+    ]
+  } else if (current_cpu == "armv7" || current_cpu == "arm") {
+    common_ios_flags += [
+      "-arch",
+      "armv7",
+    ]
+  } else if (current_cpu == "arm64") {
+    common_ios_flags += [
+      "-arch",
+      "arm64",
+    ]
+  }
+
+  # This is here so that all files get recompiled after an Xcode update.
+  # (defines are passed via the command line, and build system rebuild things
+  # when their commandline changes). Nothing should ever read this define.
+  defines = [ "CR_XCODE_VERSION=$xcode_version" ]
+
+  asmflags = common_ios_flags
+  cflags = common_ios_flags
+
+  # Without this, the constructors and destructors of a C++ object inside
+  # an Objective C struct won't be called, which is very bad.
+  cflags_objcc = [ "-fobjc-call-cxx-cdtors" ]
+
+  cflags_c = [ "-std=c99" ]
+  cflags_objc = cflags_c
+
+  ldflags = common_ios_flags
+}
+
 # This is included by reference in the //build/config/compiler:runtime_library
 # config that is applied to all targets. It is here to separate out the logic
 # that is iOS-only. Please see that target for advice on what should go in
 # :runtime_library vs. :compiler.
 config("runtime_library") {
   common_flags = [
     "-isysroot",
     sysroot,
 
     "-stdlib=libc++",
@@ skipping 24 matching lines @@
       "-isystem",
       rebase_path("//third_party/llvm-build/Release+Asserts/include/c++/v1",
                   root_build_dir),
     ]
 
     cflags_cc = common_cc_flags
     cflags_objcc = common_cc_flags
   }
 }
 
+config("ios_executable_flags") {
+}
+
 config("ios_dynamic_flags") {
   ldflags = [ "-Wl,-ObjC" ]  # Always load Objective-C categories and class.
 }
 
 config("xctest_config") {
   common_flags = [
     "-F",
     "$ios_sdk_platform_path/Developer/Library/Frameworks",
   ]
 
   cflags = common_flags
   ldflags = common_flags
 
   libs = [
     "Foundation.framework",
     "XCTest.framework",
   ]
 }
 
 group("xctest") {
   public_configs = [ ":xctest_config" ]
 }