Preparse lazy function parameters

src/parsing/preparser.cc

Index: src/parsing/preparser.cc
diff --git a/src/parsing/preparser.cc b/src/parsing/preparser.cc
index 025633c3f90cecec8a1b96ab42ac58fc2fb1573e..1ddda66b4e2037409af95aeeda141896b8e01a6c 100644
--- a/src/parsing/preparser.cc
+++ b/src/parsing/preparser.cc
@@ -84,8 +84,9 @@ PreParserIdentifier PreParser::GetSymbol() const {
 }
 
 PreParser::PreParseResult PreParser::PreParseFunction(
-    DeclarationScope* function_scope, bool parsing_module, SingletonLogger* log,
-    bool is_inner_function, bool may_abort, int* use_counts) {
+    FunctionKind kind, DeclarationScope* function_scope, bool parsing_module,
+    SingletonLogger* log, bool is_inner_function, bool may_abort,
+    int* use_counts) {
   DCHECK_EQ(FUNCTION_SCOPE, function_scope->scope_type());
   parsing_module_ = parsing_module;
   log_ = log;
@@ -98,24 +99,63 @@ PreParser::PreParseResult PreParser::PreParseFunction(
   // PreParser.
   DCHECK_NULL(scope_state_);
   FunctionState function_state(&function_state_, &scope_state_, function_scope);
-  DCHECK_EQ(Token::LBRACE, scanner()->current_token());
-  bool ok = true;
-  int start_position = peek_position();
-  LazyParsingResult result = ParseStatementListAndLogFunction(may_abort, &ok);
+  // This indirection is needed so that we can use the CHECK_OK macros.
+  bool ok_holder = true;
+  bool* ok = &ok_holder;
+
+  PreParserFormalParameters formals(function_scope);
+  bool has_duplicate_parameters = false;
+  DuplicateFinder duplicate_finder(scanner()->unicode_cache());
+  std::unique_ptr<ExpressionClassifier> formals_classifier;
+
+  // Parse non-arrow function parameters. For arrow functions, the parameters
+  // have already been parsed.
+  if (!IsArrowFunction(kind)) {
+    formals_classifier.reset(new ExpressionClassifier(this, &duplicate_finder));
+    // We return kPreParseSuccess in failure cases too - errors are retrieved
+    // separately by Parser::SkipLazyFunctionBody.
+    ParseFormalParameterList(&formals, CHECK_OK_VALUE(kPreParseSuccess));
+    Expect(Token::RPAREN, CHECK_OK_VALUE(kPreParseSuccess));
+    int formals_end_position = scanner()->location().end_pos;
+
+    CheckArityRestrictions(
+        formals.arity, kind, formals.has_rest, function_scope->start_position(),
+        formals_end_position, CHECK_OK_VALUE(kPreParseSuccess));
+    has_duplicate_parameters =
+        !classifier()->is_valid_formal_parameter_list_without_duplicates();
+  }
+
+  Expect(Token::LBRACE, CHECK_OK_VALUE(kPreParseSuccess));
+  LazyParsingResult result = ParseStatementListAndLogFunction(
+      function_scope->start_position(), &formals, has_duplicate_parameters,
+      may_abort, ok);
   use_counts_ = nullptr;
   track_unresolved_variables_ = false;
   if (result == kLazyParsingAborted) {
     return kPreParseAbort;
   } else if (stack_overflow()) {
     return kPreParseStackOverflow;
-  } else if (!ok) {
+  } else if (!*ok) {
     DCHECK(log->has_error());
   } else {
     DCHECK_EQ(Token::RBRACE, scanner()->peek());
+
+    if (!IsArrowFunction(kind)) {
+      // Validate parameter names. We can do this only after parsing the
+      // function, since the function can declare itself strict.
+      const bool allow_duplicate_parameters =
+          is_sloppy(function_scope->language_mode()) && formals.is_simple &&
+          !IsConciseMethod(kind);
+      ValidateFormalParameters(function_scope->language_mode(),
+                               allow_duplicate_parameters,
+                               CHECK_OK_VALUE(kPreParseSuccess));
+    }
+
     if (is_strict(function_scope->language_mode())) {
       int end_pos = scanner()->location().end_pos;
-      CheckStrictOctalLiteral(start_position, end_pos, &ok);
-      CheckDecimalLiteralWithLeadingZero(start_position, end_pos);
+      CheckStrictOctalLiteral(function_scope->start_position(), end_pos, ok);
+      CheckDecimalLiteralWithLeadingZero(function_scope->start_position(),
+                                         end_pos);
     }
   }
   return kPreParseSuccess;
@@ -195,8 +235,8 @@ PreParser::Expression PreParser::ParseFunctionLiteral(
 }
 
 PreParser::LazyParsingResult PreParser::ParseStatementListAndLogFunction(
-    bool may_abort, bool* ok) {
-  int body_start = position();
+    int start_position, PreParserFormalParameters* formals,
+    bool has_duplicate_parameters, bool may_abort, bool* ok) {
   PreParserStatementList body;
   LazyParsingResult result = ParseStatementList(
       body, Token::RBRACE, may_abort, CHECK_OK_VALUE(kLazyParsingComplete));
@@ -207,7 +247,8 @@ PreParser::LazyParsingResult PreParser::ParseStatementListAndLogFunction(
   int body_end = scanner()->peek_location().end_pos;
   DeclarationScope* scope = this->scope()->AsDeclarationScope();
   DCHECK(scope->is_function_scope());
-  log_->LogFunction(body_start, body_end,
+  log_->LogFunction(start_position, body_end, formals->num_parameters(),
+                    formals->function_length, has_duplicate_parameters,
                     function_state_->materialized_literal_count(),
                     function_state_->expected_property_count(), language_mode(),
                     scope->uses_super_property(), scope->calls_eval());