Always capture instantiator in async functions

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 6803 matching lines @@
     Type& signature_type = Type::Handle(Z, closure.SignatureType());
     signature_type ^= ClassFinalizer::FinalizeType(
         current_class(), signature_type, ClassFinalizer::kCanonicalize);
     closure.SetSignatureType(signature_type);
     ASSERT(AbstractType::Handle(Z, closure.result_type()).IsResolved());
     ASSERT(closure.NumParameters() == closure_params.parameters->length());
   }
   OpenFunctionBlock(closure);
   AddFormalParamsToScope(&closure_params, current_block_->scope);
   async_temp_scope_ = current_block_->scope;
+
+  // Capture instantiator in case it may be needed to generate the type
+  // check of the return value. (C.f. handling of Token::kRETURN.)
+  ASSERT(FunctionLevel() > 0);
+  if (I->type_checks() && IsInstantiatorRequired()) {
+    CaptureInstantiator();
+  }
   return closure.raw();
 }
 
 
 void Parser::AddContinuationVariables() {
   // Add to current block's scope:
   //   var :await_jump_var;
   //   var :await_ctx_var;
   LocalVariable* await_jump_var = new (Z) LocalVariable(
       TokenPosition::kNoSource,
@@ skipping 3304 matching lines @@
       if (current_function().IsGenerativeConstructor() &&
           (function_level == 0)) {
         ReportError(expr_pos,
                     "return of a value is not allowed in constructors");
       } else if (current_function().IsGeneratorClosure() &&
           (function_level == 0)) {
         ReportError(expr_pos, "generator functions may not return a value");
       }
       AstNode* expr = ParseAwaitableExpr(kAllowConst, kConsumeCascades, NULL);
       if (I->type_checks() &&
-          (((function_level == 0) && current_function().IsAsyncClosure()) ||
-           ((function_level > 0) && current_function().IsAsyncFunction()))) {
+          (((function_level == 0) && current_function().IsAsyncClosure()))) {
         // In checked mode, when the declared result type is Future<T>, verify
         // that the returned expression is of type T or Future<T> as follows:
         // return temp = expr, temp is Future ? temp as Future<T> : temp as T;
         // In case of a mismatch, we need a TypeError and not a CastError, so
         // we do not actually implement an "as" test, but an "assignable" test.
-        Function& async_func = Function::Handle(Z, current_function().raw());
-        if (function_level == 0) {
-          async_func = async_func.parent_function();
-        }
+        Function& async_func =
+            Function::Handle(Z, current_function().parent_function());
         const AbstractType& result_type =
             AbstractType::ZoneHandle(Z, async_func.result_type());
         const Class& future_class =
             Class::ZoneHandle(Z, I->object_store()->future_class());
         ASSERT(!future_class.IsNull());
         if (result_type.type_class() == future_class.raw()) {
           const TypeArguments& result_type_args =
               TypeArguments::ZoneHandle(Z, result_type.arguments());
           if (!result_type_args.IsNull() && (result_type_args.Length() == 1)) {
             const AbstractType& result_type_arg =
                 AbstractType::ZoneHandle(Z, result_type_args.TypeAt(0));
-            if (function_level == 0) {
-              // Parsing and generating code for async closure.
-              LetNode* checked_expr = new(Z) LetNode(expr_pos);
-              LocalVariable* temp = checked_expr->AddInitializer(expr);
-              temp->set_is_final();
-              const AbstractType& future_type =
-                  AbstractType::ZoneHandle(Z, future_class.RareType());
-              AstNode* is_future = new(Z) LoadLocalNode(expr_pos, temp);
-              is_future = new(Z) ComparisonNode(expr_pos,
-                                                Token::kIS,
-                                                is_future,
-                                                new(Z) TypeNode(expr_pos,
-                                                                future_type));
-              AstNode* as_future_t = new(Z) LoadLocalNode(expr_pos, temp);
-              as_future_t = new(Z) AssignableNode(expr_pos,
-                                                  as_future_t,
-                                                  result_type,
-                                                  Symbols::FunctionResult());
-              AstNode* as_t = new(Z) LoadLocalNode(expr_pos, temp);
-              as_t = new(Z) AssignableNode(expr_pos,
-                                           as_t,
-                                           result_type_arg,
-                                           Symbols::FunctionResult());
-              checked_expr->AddNode(new(Z) ConditionalExprNode(expr_pos,
-                                                               is_future,
-                                                               as_future_t,
-                                                               as_t));
-              expr = checked_expr;
-            } else {
-              // Parsing async function, but not generating async closure code.
-              if (!result_type_arg.IsInstantiated()) {
-                // Make sure that the instantiator is captured.
-                CaptureInstantiator();
-              }
-            }
+            LetNode* checked_expr = new(Z) LetNode(expr_pos);
+            LocalVariable* temp = checked_expr->AddInitializer(expr);
+            temp->set_is_final();
+            const AbstractType& future_type =
+                AbstractType::ZoneHandle(Z, future_class.RareType());
+            AstNode* is_future = new(Z) LoadLocalNode(expr_pos, temp);
+            is_future = new(Z) ComparisonNode(expr_pos,
+                                              Token::kIS,
+                                              is_future,
+                                              new(Z) TypeNode(expr_pos,
+                                                              future_type));
+            AstNode* as_future_t = new(Z) LoadLocalNode(expr_pos, temp);
+            as_future_t = new(Z) AssignableNode(expr_pos,
+                                                as_future_t,
+                                                result_type,
+                                                Symbols::FunctionResult());
+            AstNode* as_t = new(Z) LoadLocalNode(expr_pos, temp);
+            as_t = new(Z) AssignableNode(expr_pos,
+                                         as_t,
+                                         result_type_arg,
+                                         Symbols::FunctionResult());
+            checked_expr->AddNode(new(Z) ConditionalExprNode(expr_pos,
+                                                             is_future,
+                                                             as_future_t,
+                                                             as_t));
+            expr = checked_expr;
           }
         }
       }
       statement = new(Z) ReturnNode(statement_pos, expr);
     } else {
       if (current_function().IsSyncGenClosure() &&
           (FunctionLevel() == 0)) {
         // In a synchronous generator, return without an expression
         // returns false, signaling that the iterator terminates and
         // did not yield a value.
@@ skipping 4415 matching lines @@
     const ArgumentListNode& function_args,
     const LocalVariable* temp_for_last_arg,
     bool is_super_invocation) {
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME