Remove duplicate -std=gnu++11 flag for 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 (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
   import("//build/config/mips.gni")
@@ skipping 176 matching lines @@
       ]
     }
 
     cflags += common_mac_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_cc += [ "-std=gnu++11" ]
 
     ldflags += common_mac_flags
   } else if (is_posix) {
     # Non-Mac Posix compiler flags setup.
     # -----------------------------------
     if (gcc_version >= 48) {
       cflags_cc += [ "-std=gnu++11" ]
     }
 
     if (enable_profiling && !is_debug) {
@@ skipping 198 matching lines @@
   if (linux_use_bundled_binutils) {
     binutils_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
                                 root_build_dir)
     cflags += [ "-B$binutils_path" ]
   }
 
   # Clang-specific compiler flags setup.
   # ------------------------------------
   if (is_clang) {
     cflags += [ "-fcolor-diagnostics" ]
     cflags_cc += [ "-std=gnu++11" ]

[Nico, 2015/04/14 15:17:16]

It should be -std=c++11 on non-linux

[Jiang Jiang, 2015/04/14 15:28:44]

So basically:

if (is_clang) {
  ...
 
  if (is_linux) {
    # gnu++11 instead of c++11 is needed because some code uses typeof() (a GNU
    # extension).
    # TODO(thakis): Eventually switch this to c++11 instead,
    # http://crbug.com/427584
    cflags_cc += [ "-std=gnu++11" ]
  } else {
    cflags_cc += [ "-std=c++11" ]
  }
}

Sounds OK to you?

   }
 
   # Android-specific flags setup.
   # -----------------------------
   if (is_android) {
     cflags += [
       "-ffunction-sections",
       "-funwind-tables",
       "-fno-short-enums",
     ]
@@ skipping 654 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }