build: add build option suppress_all_error_on_warn

common.gypi

@@ -27,6 +27,7 @@
 
     'clang%': 0,
     'error_on_warn%': 'false',
+    'suppress_all_error_on_warn%': 'false',
 
     'openssl_product': '<(STATIC_LIB_PREFIX)openssl<(STATIC_LIB_SUFFIX)',
     'openssl_no_asm%': 0,

configure.py

@@ -149,6 +149,12 @@
     default=None,
     help='Turn compiler warnings into errors for node core sources.')
 
+parser.add_argument('--suppress-all-error-on-warn',
+    action='store_true',
+    dest='suppress_all_error_on_warn',
+    default=False,
+    help='Suppress cases where compiler warnings are turned into errors by default.')
+
 parser.add_argument('--gdb',
     action='store_true',
     dest='gdb',
@@ -1397,7 +1403,10 @@ def configure_node(o):
   o['variables']['node_use_amaro'] = b(not options.without_amaro)
   o['variables']['debug_node'] = b(options.debug_node)
   o['default_configuration'] = 'Debug' if options.debug else 'Release'
+  if options.error_on_warn and options.suppress_all_error_on_warn:
+    raise Exception('--error_on_warn is incompatible with --suppress_all_error_on_warn.')
   o['variables']['error_on_warn'] = b(options.error_on_warn)
+  o['variables']['suppress_all_error_on_warn'] = b(options.suppress_all_error_on_warn)
   o['variables']['use_prefix_to_find_headers'] = b(options.use_prefix_to_find_headers)
 
   host_arch = host_arch_win() if os.name == 'nt' else host_arch_cc()

node.gyp

@@ -871,8 +871,6 @@
         'openssl_default_cipher_list%': '',
       },
 
-      'cflags': ['-Werror=unused-result'],
-
       'defines': [
         'NODE_ARCH="<(target_arch)"',
         'NODE_PLATFORM="<(OS)"',
@@ -893,6 +891,9 @@
             'NODE_OPENSSL_DEFAULT_CIPHER_LIST="<(openssl_default_cipher_list)"'
            ]
         }],
+        [ 'suppress_all_error_on_warn=="false"', {
+          'cflags': ['-Werror=unused-result'],
+        }],
         [ 'error_on_warn=="true"', {
           'cflags': ['-Werror'],
           'xcode_settings': {