Private fields

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index 22c09d54a103876ec7eb6742c1c65596f01b021f..878538c784f5674b30884340fe637f25bf655c73 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -198,7 +198,8 @@ class ParserBase {
         allow_harmony_async_await_(false),
         allow_harmony_restrictive_generators_(false),
         allow_harmony_trailing_commas_(false),
-        allow_harmony_class_fields_(false) {}
+        allow_harmony_class_fields_(false),
+        allow_harmony_private_class_fields_(false) {}
 
 #define ALLOW_ACCESSORS(name)                           \
   bool allow_##name() const { return allow_##name##_; } \
@@ -215,6 +216,7 @@ class ParserBase {
   ALLOW_ACCESSORS(harmony_restrictive_generators);
   ALLOW_ACCESSORS(harmony_trailing_commas);
   ALLOW_ACCESSORS(harmony_class_fields);
+  ALLOW_ACCESSORS(harmony_private_class_fields);
 
 #undef ALLOW_ACCESSORS
 
@@ -1105,8 +1107,8 @@ class ParserBase {
                                 bool* ok);
   ExpressionT ParseObjectLiteral(bool* ok);
   ClassLiteralPropertyT ParseClassPropertyDefinition(
-      ClassLiteralChecker* checker, bool has_extends, bool* is_computed_name,
-      bool* has_seen_constructor, bool* ok);
+      ClassLiteralChecker* checker, bool has_extends, IdentifierT* private_name,
+      bool* is_computed_name, bool* has_seen_constructor, bool* ok);
   FunctionLiteralT ParseClassFieldForInitializer(bool has_initializer,
                                                  bool* ok);
   ObjectLiteralPropertyT ParseObjectPropertyDefinition(
@@ -1341,6 +1343,7 @@ class ParserBase {
   bool allow_harmony_restrictive_generators_;
   bool allow_harmony_trailing_commas_;
   bool allow_harmony_class_fields_;
+  bool allow_harmony_private_class_fields_;
 
   friend class DiscardableZoneScope;
 };
@@ -1605,6 +1608,7 @@ typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParsePrimaryExpression(
   //   TemplateLiteral
   //   do Block
   //   AsyncFunctionExpression
+  //   PrivateName
 
   int beg_pos = peek_position();
   switch (peek()) {
@@ -1728,6 +1732,14 @@ typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParsePrimaryExpression(
       }
       break;
 
+    case Token::HASH:
+      if (allow_harmony_private_class_fields()) {
+        BindingPatternUnexpectedToken();
+        return impl()->ParsePrivateFieldReference(
+            impl()->ThisExpression(beg_pos), ok);
+      }
+      break;
+
     default:
       break;
   }
@@ -2014,11 +2026,10 @@ typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParsePropertyName(
 
 template <typename Impl>
 typename ParserBase<Impl>::ClassLiteralPropertyT
-ParserBase<Impl>::ParseClassPropertyDefinition(ClassLiteralChecker* checker,
-                                               bool has_extends,
-                                               bool* is_computed_name,
-                                               bool* has_seen_constructor,
-                                               bool* ok) {
+ParserBase<Impl>::ParseClassPropertyDefinition(
+    ClassLiteralChecker* checker, bool has_extends, IdentifierT* private_name,
+    bool* is_computed_name, bool* has_seen_constructor, bool* ok) {
+  DCHECK(!allow_harmony_private_class_fields() || private_name != nullptr);
   DCHECK(has_seen_constructor != nullptr);
   bool is_get = false;
   bool is_set = false;
@@ -2047,6 +2058,21 @@ ParserBase<Impl>::ParseClassPropertyDefinition(ClassLiteralChecker* checker,
           &name, &kind, &is_generator, &is_get, &is_set, &is_async,
           is_computed_name, CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
     }
+  } else if (allow_harmony_private_class_fields() &&
+             name_token == Token::HASH) {
+    Consume(Token::HASH);
+    // Private field
+    *private_name = ParseIdentifierName(CHECK_OK_CUSTOM(
+        EmptyClassLiteralProperty));  // TODO(bakkot) IdentifierPart
+    name_expression = impl()->EmptyExpression();
+
+    bool has_initializer = Check(Token::ASSIGN);
+    FunctionLiteralT function_literal = ParseClassFieldForInitializer(
+        has_initializer, CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
+    ExpectSemicolon(CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
+    return factory()->NewClassLiteralProperty(name_expression, function_literal,
+                                              ClassLiteralProperty::FIELD,
+                                              false, false);
   } else {
     name_expression = ParsePropertyName(
         &name, &kind, &is_generator, &is_get, &is_set, &is_async,
@@ -3373,6 +3399,10 @@ ParserBase<Impl>::ParseMemberExpressionContinuation(ExpressionT expression,
         ArrowFormalParametersUnexpectedToken();
 
         Consume(Token::PERIOD);
+        if (allow_harmony_private_class_fields() && peek() == Token::HASH) {
+          expression = impl()->ParsePrivateFieldReference(expression, CHECK_OK);
+          break;
+        }
         int pos = position();
         IdentifierT name = ParseIdentifierName(CHECK_OK);
         expression = factory()->NewProperty(