[clang] Set correct clang warning flags.

build/standalone.gypi

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 181 matching lines @@
         # Xcode insists on this empty entry.
       },
     },
     'target_conditions': [
       ['v8_code == 0', {
         'defines!': [
           'DEBUG',
         ],
         'conditions': [
           ['os_posix == 1 and OS != "mac"', {
+            # We don't want to get warnings from third-party code,
+            # so remove any existing warning-enabling flags like -Wall.
             'cflags!': [
+              '-pedantic',
+              '-Wall',
               '-Werror',
+              '-Wextra',
+            ],
+            # Clang considers the `register` keyword as deprecated, but
+            # icu uses it all over the place.
+            'cflags+': [
+              '-Wno-deprecated-register',
+            ],
+            'cflags_cc!': [
+              '-Wnon-virtual-dtor',
             ],
           }],
           ['OS == "mac"', {
             'xcode_settings': {
               'GCC_TREAT_WARNINGS_AS_ERRORS': 'NO',    # -Werror
             },
           }],
           ['OS == "win"', {
             'msvs_settings': {
               'VCCLCompilerTool': {
@@ skipping 65 matching lines @@
           '<(DEPTH)/build/mac/asan.gyp:asan_dynamic_runtime',
         ],
       },
     }],
     ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
        or OS=="netbsd" or OS=="aix"', {
       'target_defaults': {
         'cflags': [
           '-Wall',
           '<(werror)',
-          '-W',
           '-Wno-unused-parameter',
           '-Wno-long-long',
           '-pthread',
           '-fno-exceptions',
           '-pedantic',
           # Don't warn about the "struct foo f = {0};" initialization pattern.
           '-Wno-missing-field-initializers',
         ],
         'cflags_cc': [ '-Wnon-virtual-dtor', '-fno-rtti', '-std=gnu++0x' ],
         'ldflags': [ '-pthread', ],
@@ skipping 10 matching lines @@
         ],
       },
     }],
     # 'OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"
     #  or OS=="netbsd"'
     ['OS=="qnx"', {
       'target_defaults': {
         'cflags': [
           '-Wall',
           '<(werror)',
-          '-W',
           '-Wno-unused-parameter',
           '-fno-exceptions',
           # Don't warn about the "struct foo f = {0};" initialization pattern.
           '-Wno-missing-field-initializers',
         ],
         'cflags_cc': [ '-Wnon-virtual-dtor', '-fno-rtti', '-std=gnu++0x' ],
         'conditions': [
           [ 'visibility=="hidden"', {
             'cflags': [ '-fvisibility=hidden' ],
           }],
@@ skipping 122 matching lines @@
           'MACOSX_DEPLOYMENT_TARGET': '<(mac_deployment_target)',
           'PREBINDING': 'NO',                       # No -Wl,-prebind
           'SYMROOT': '<(DEPTH)/xcodebuild',
           'USE_HEADERMAP': 'NO',
           'OTHER_CFLAGS': [
             '-fno-strict-aliasing',
           ],
           'WARNING_CFLAGS': [
             '-Wall',
             '-Wendif-labels',
-            '-W',
             '-Wno-unused-parameter',
             # Don't warn about the "struct foo f = {0};" initialization pattern.
             '-Wno-missing-field-initializers',
           ],
         },
         'conditions': [
           ['werror==""', {
             'xcode_settings': {'GCC_TREAT_WARNINGS_AS_ERRORS': 'NO'},
           }, {
             'xcode_settings': {'GCC_TREAT_WARNINGS_AS_ERRORS': 'YES'},
@@ skipping 42 matching lines @@
     ['use_goma==1 and ("<(GENERATOR)"=="ninja" or clang==1)', {
       'make_global_settings': [
        ['CC_wrapper', '<(gomadir)/gomacc'],
        ['CXX_wrapper', '<(gomadir)/gomacc'],
        ['CC.host_wrapper', '<(gomadir)/gomacc'],
        ['CXX.host_wrapper', '<(gomadir)/gomacc'],
       ],
     }],
   ],
 }