Enable -Wunused-local-typedef

chrome/browser/ui/libgtk2ui/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.
 
 assert(is_linux, "This file should only be referenced on Linux")
 
 import("//build/config/features.gni")
 import("//build/config/linux/pkg_config.gni")
 
 pkg_config("gtk") {
@@ skipping 54 matching lines @@
     "x11_input_method_context_impl_gtk2.cc",
     "x11_input_method_context_impl_gtk2.h",
   ]
 
   if (use_gconf) {
     sources += [
       "gconf_listener.cc",
       "gconf_listener.h",
     ]
   }
-  if (is_clang) {
-    # G_DEFINE_TYPE automatically generates a *get_instance_private inline
-    # function after glib 2.37. That's unused. Prevent to complain about it.
-    cflags = [ "-Wno-unused-function" ]
-  }
-
   defines = [ "LIBGTK2UI_IMPLEMENTATION" ]
 
   configs += [
     ":gtk",
     ":gtkprint",
     "//build/config/linux:gconf",
     "//printing:cups",
   ]
 
+  # gn orders flags on a target before flags from configs. The default config
+  # adds -Wall, and these flags have to be after -Wall -- so they need to come
+  # from a config and can't be on the target directly.
+  config("libgtk2ui_warnings") {
+    if (is_clang) {
+      cflags = [
+        # G_DEFINE_TYPE automatically generates a *get_instance_private inline
+        # function after glib 2.37. That's unused. Prevent to complain about it.
+        "-Wno-unused-function",
+
+        # G_STATIC_ASSERT uses a typedef as a static_assert.
+        "-Wno-unused-local-typedef",
+      ]
+    }
+  }
+  configs += [ ":libgtk2ui_warnings", ]
+
   deps = [
     "//base",
     "//base:i18n",
     "//base/third_party/dynamic_annotations",
     "//chrome/app/theme:theme_resources",
     "//chrome:extra_resources",
     "//chrome:resources",
     "//chrome:strings",
     "//components/resources",
     "//skia",
     "//ui/base",
     "//ui/resources",
     "//ui/strings",
     "//ui/views",
   ]
 }