build: compile with C++20 support

Author: targos

common_node.gypi

@@ -0,0 +1,16 @@
+{
+  'target_defaults': {
+    'conditions': [
+      # Override common.gypi config to use C++20 for Node.js core only.
+      ['OS in "linux freebsd openbsd solaris android aix os400 cloudabi"', {
+        'cflags_cc!': ['-std=gnu++17'],
+        'cflags_cc': ['-std=gnu++20'],
+      }],
+      ['OS=="mac" and clang==1', {
+        'xcode_settings': {
+          'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++20',  # -std=gnu++20
+        },
+      }],
+    ],
+  },
+}

tools/gyp_node.py

@@ -20,11 +20,15 @@ def run_gyp(args):
   a_path = node_root if sys.platform == 'win32' else os.path.abspath(node_root)
   args.append(os.path.join(a_path, 'node.gyp'))
   common_fn = os.path.join(a_path, 'common.gypi')
+  common_node_fn = os.path.join(a_path, 'common_node.gypi')
   options_fn = os.path.join(a_path, 'config.gypi')
 
   if os.path.exists(common_fn):
     args.extend(['-I', common_fn])
 
+  if os.path.exists(common_node_fn):
+    args.extend(['-I', common_node_fn])
+
   if os.path.exists(options_fn):
     args.extend(['-I', options_fn])