Revert of Reland: [modules] Properly initialize declared variables.

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 7cb930564fa60942506a56af4b2286beb3abe89e..907948129aae320fc51f8349cca011c1b1a8d7c0 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -768,13 +768,12 @@
   {
     Scope* outer = original_scope_;
     DCHECK_NOT_NULL(outer);
-    parsing_module_ = info->is_module();
     if (info->is_eval()) {
       if (!outer->is_script_scope() || is_strict(info->language_mode())) {
         parsing_mode = PARSE_EAGERLY;
       }
       outer = NewEvalScope(outer);
-    } else if (parsing_module_) {
+    } else if (info->is_module()) {
       DCHECK_EQ(outer, info->script_scope());
       outer = NewModuleScope(info->script_scope());
       // Never do lazy parsing in modules.  If we want to support this in the
@@ -794,6 +793,7 @@
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16, zone());
     bool ok = true;
     int beg_pos = scanner()->location().beg_pos;
+    parsing_module_ = info->is_module();
     if (parsing_module_) {
       // Declare the special module parameter.
       auto name = ast_value_factory()->empty_string();
@@ -804,13 +804,6 @@
                                          &is_duplicate, ast_value_factory());
       DCHECK(!is_duplicate);
       var->AllocateTo(VariableLocation::PARAMETER, 0);
-
-      PrepareGeneratorVariables(&function_state);
-      Expression* initial_yield =
-          BuildInitialYield(kNoSourcePosition, kGeneratorFunction);
-      body->Add(
-          factory()->NewExpressionStatement(initial_yield, kNoSourcePosition),
-          zone());
 
       ParseModuleItemList(body, &ok);
       ok = ok &&
@@ -2536,20 +2529,6 @@
   }
 }
 
-void Parser::PrepareGeneratorVariables(FunctionState* function_state) {
-  // For generators, allocating variables in contexts is currently a win
-  // because it minimizes the work needed to suspend and resume an
-  // activation.  The machine code produced for generators (by full-codegen)
-  // relies on this forced context allocation, but not in an essential way.
-  scope()->ForceContextAllocation();
-
-  // Calling a generator returns a generator object.  That object is stored
-  // in a temporary variable, a definition that is used by "yield"
-  // expressions.
-  Variable* temp =
-      NewTemporary(ast_value_factory()->dot_generator_object_string());
-  function_state->set_generator_object_variable(temp);
-}
 
 FunctionLiteral* Parser::ParseFunctionLiteral(
     const AstRawString* function_name, Scanner::Location function_name_location,
@@ -2671,7 +2650,20 @@
 
   ExpressionClassifier formals_classifier(this, &duplicate_finder);
 
-  if (is_generator) PrepareGeneratorVariables(&function_state);
+  if (is_generator) {
+    // For generators, allocating variables in contexts is currently a win
+    // because it minimizes the work needed to suspend and resume an
+    // activation.  The machine code produced for generators (by full-codegen)
+    // relies on this forced context allocation, but not in an essential way.
+    this->scope()->ForceContextAllocation();
+
+    // Calling a generator returns a generator object.  That object is stored
+    // in a temporary variable, a definition that is used by "yield"
+    // expressions. This also marks the FunctionState as a generator.
+    Variable* temp =
+        NewTemporary(ast_value_factory()->dot_generator_object_string());
+    function_state.set_generator_object_variable(temp);
+  }
 
   Expect(Token::LPAREN, CHECK_OK);
   int start_position = scanner()->location().beg_pos;
@@ -3132,21 +3124,6 @@
   return promise;
 }
 
-Expression* Parser::BuildInitialYield(int pos, FunctionKind kind) {
-  Expression* allocation = BuildCreateJSGeneratorObject(pos, kind);
-  VariableProxy* init_proxy =
-      factory()->NewVariableProxy(function_state_->generator_object_variable());
-  Assignment* assignment = factory()->NewAssignment(
-      Token::INIT, init_proxy, allocation, kNoSourcePosition);
-  VariableProxy* get_proxy =
-      factory()->NewVariableProxy(function_state_->generator_object_variable());
-  // The position of the yield is important for reporting the exception
-  // caused by calling the .throw method on a generator suspended at the
-  // initial yield (i.e. right after generator instantiation).
-  return factory()->NewYield(get_proxy, assignment, scope()->start_position(),
-                             Yield::kOnExceptionThrow);
-}
-
 ZoneList<Statement*>* Parser::ParseEagerFunctionBody(
     const AstRawString* function_name, int pos,
     const ParserFormalParameters& parameters, FunctionKind kind,
@@ -3199,10 +3176,26 @@
 
       Block* try_block =
           factory()->NewBlock(nullptr, 3, false, kNoSourcePosition);
-      Expression* initial_yield = BuildInitialYield(pos, kind);
-      try_block->statements()->Add(
-          factory()->NewExpressionStatement(initial_yield, kNoSourcePosition),
-          zone());
+
+      {
+        Expression* allocation = BuildCreateJSGeneratorObject(pos, kind);
+        VariableProxy* init_proxy = factory()->NewVariableProxy(
+            function_state_->generator_object_variable());
+        Assignment* assignment = factory()->NewAssignment(
+            Token::INIT, init_proxy, allocation, kNoSourcePosition);
+        VariableProxy* get_proxy = factory()->NewVariableProxy(
+            function_state_->generator_object_variable());
+        // The position of the yield is important for reporting the exception
+        // caused by calling the .throw method on a generator suspended at the
+        // initial yield (i.e. right after generator instantiation).
+        Yield* yield = factory()->NewYield(get_proxy, assignment,
+                                           scope()->start_position(),
+                                           Yield::kOnExceptionThrow);
+        try_block->statements()->Add(
+            factory()->NewExpressionStatement(yield, kNoSourcePosition),
+            zone());
+      }
+
       ParseStatementList(try_block->statements(), Token::RBRACE, CHECK_OK);
 
       Statement* final_return = factory()->NewReturnStatement(