Make it possible to disable fatal linker warnings

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1212 matching lines @@
 
     # Enable EGLImage support in OpenMAX
     'enable_eglimage%': 1,
 
     # .gyp files or targets should set chromium_code to 1 if they build
     # Chromium-specific code, as opposed to external code.  This variable is
     # used to control such things as the set of warnings to enable, and
     # whether warnings are treated as errors.
     'chromium_code%': 0,
 
+    # Disable fatal linker warnings, similarly to how we make it possible
+    # to disable -Werror (e.g. for different toolchain versions).
+    'disable_fatal_linker_warnings%': 0,
+
     'release_valgrind_build%': 0,
 
     # TODO(thakis): Make this a blacklist instead, http://crbug.com/101600
     'enable_wexit_time_destructors%': 0,
 
     # Build libpeerconnection as a static library by default.
     'libpeer_target_type%': 'static_library',
 
     # Set to 1 to compile with the built in pdf viewer.
     'internal_pdf%': 0,
@@ skipping 1819 matching lines @@
             'inherit_from': ['Common_Base', 'x64_Base', 'Debug_Base'],
           },
           'Release_x64': {
             'inherit_from': ['Common_Base', 'x64_Base', 'Release_Base'],
           },
         }],
       ],
     },
   },
   'conditions': [
+    ['os_posix==1', {
+      'target_defaults': {
+        'ldflags': [
+          '-Wl,-z,now',
+          '-Wl,-z,relro',
+        ],
+      },
+    }],
     # TODO(jochen): Enable this on chromeos on arm. http://crbug.com/356580
-    ['os_posix==1 and (chromeos==0 or target_arch!="arm")', {
+    ['os_posix==1 and disable_fatal_linker_warnings==0 and (chromeos==0 or target_arch!="arm")', {
       'target_defaults': {
         'ldflags': [
           '-Wl,--fatal-warnings',
-          '-Wl,-z,now',
-          '-Wl,-z,relro',
         ],
       },
     }],
     ['os_posix==1 and chromeos==0', {
       # Chrome OS enables -fstack-protector-strong via its build wrapper,
       # and we want to avoid overriding this, so stack-protector is only
       # enabled when not building on Chrome OS.
       # TODO(phajdan.jr): Use -fstack-protector-strong when our gcc
       # supports it.
       'target_defaults': {
@@ skipping 2128 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }