Work on Mac GN build

build/config/compiler/BUILD.gn

 # Copyright (c) 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("//build/config/android/config.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 
 # compiler ---------------------------------------------------------------------
@@ skipping 499 matching lines @@
       "-Wno-missing-field-initializers",  # "struct foo f = {0};"
       "-Wno-unused-parameter",  # Unused function parameters.
     ]
 
     if (is_mac) {
       cflags += [
         "-Wnewline-eof",
       ]
     }
 
-    # TODO(brettw) Ones below here should be clang-only when we have a flag
-    # for it.
     if (is_clang) {
       cflags += [
-        "-Wheader-hygiene",
-
         # This warns on using ints as initializers for floats in
         # initializer lists (e.g. |int a = f(); CGSize s = { a, a };|),
         # which happens in several places in chrome code. Not sure if
         # this is worth fixing.
         "-Wno-c++11-narrowing",
 
         # Don't die on dtoa code that uses a char as an array index.
         # This is required solely for base/third_party/dmg_fp/dtoa.cc.
         # TODO(brettw) move this to that project then!
         "-Wno-char-subscripts",
 
         # Warns on switches on enums that cover all enum values but
         # also contain a default: branch. Chrome is full of that.
         "-Wno-covered-switch-default",
 
         # Clang considers the `register` keyword as deprecated, but e.g.
         # code generated by flex (used in angle) contains that keyword.
         # http://crbug.com/255186
         "-Wno-deprecated-register",
 
         # Clang spots more unused functions.
         "-Wno-unused-function",
-
-        # Warns when a const char[] is converted to bool.
-        "-Wstring-conversion",
       ]
     }
 
     if (is_android) {
       # Disable any additional warnings enabled by the Android build system but
       # which chromium does not build cleanly with (when treating warning as
       # errors).
       cflags += [
         "-Wno-extra",
         "-Wno-ignored-qualifiers",
@@ skipping 112 matching lines @@
     cflags = [ "-g1" ]
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }