Rolling forward clang, hiding some warnings

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")
 import("//build/config/chrome_build.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
@@ skipping 921 matching lines @@
     # which we no longer use. Check if it makes sense to remove
     # this as well. http://crbug.com/316352
     "-Wno-unneeded-internal-declaration",
 
     # TODO(thakis): Remove, http://crbug.com/263960
     "-Wno-reserved-user-defined-literal",
 
     # TODO(hans): Get this cleaned up.
     "-Wno-inconsistent-missing-override",
   ]
+
+  # NaCl's Clang compiler and Chrome's hermetic Clang compiler will almost
+  # always have different versions. Certain flags may not be recognized by
+  # one version or the other.
+  if (!is_nacl) {
+    # Flags NaCl (Clang 3.7) does not recognize.
+    default_warning_flags += [
+      # TODO(smklein): Enable this, crbug.com/507717
+      "-Wno-shift-negative-value",
+
+      # TODO(smklein): Consider enabling this once not broken by third party
+      "-Wno-bitfield-width",
+    ]
+  }
 }
 
 # chromium_code ---------------------------------------------------------------
 #
 # Toggles between higher and lower warnings for code that is (or isn't)
 # part of Chromium.
 
 config("chromium_code") {
   if (is_win) {
     cflags = [ "/W4" ]  # Warning level 4.
@@ skipping 47 matching lines @@
       "_CRT_NONSTDC_NO_WARNINGS",
       "_CRT_NONSTDC_NO_DEPRECATE",
     ]
   }
 
   if (is_linux) {
     # Don't warn about ignoring the return value from e.g. close(). This is
     # off by default in some gccs but on by default in others. BSD systems do
     # not support this option, since they are usually using gcc 4.2.1, which
     # does not have this flag yet.
-    cflags += [ "-Wno-unused-result" ]
+    cflags += [
+      "-Wno-logical-not-parentheses",
+      "-Wno-unused-result",
+    ]
   }
 
   if (is_linux || is_android) {
     cflags += [
       # Don't warn about printf format problems. This is off by default in gcc
       # but on in Ubuntu's gcc(!).
       "-Wno-format",
     ]
     cflags_cc += [
       # Don't warn about hash_map in third-party code.
@@ skipping 226 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }