Avoid parsing formal type parameters a second time from inside an async body,

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 3486 matching lines @@
     // Populate function scope with the formal parameters. Since in this case
     // we are compiling a getter this will at most populate the receiver.
     AddFormalParamsToScope(&params, current_block_->scope);
   } else if (func.IsAsyncClosure()) {
     AddAsyncClosureParameters(&params);
     SetupDefaultsForOptionalParams(params);
     AddFormalParamsToScope(&params, current_block_->scope);
     ASSERT(AbstractType::Handle(Z, func.result_type()).IsResolved());
     ASSERT(func.NumParameters() == params.parameters->length());
     if (!Function::Handle(func.parent_function()).IsGetterFunction()) {
-      // Parse and discard any formal parameters. They are accessed as
-      // context variables.
-      ParamList discarded_params;
-      ParseFormalParameterList(allow_explicit_default_values,
-                               false,
-                               &discarded_params);
+      // Skip formal parameters. They are accessed as context variables.
+      // Parsing them again (and discarding them) does not work in case of
+      // default values with same name as already parsed formal parameter.
+      SkipToMatchingParenthesis();
     }
   } else if (func.IsSyncGenClosure()) {
     AddSyncGenClosureParameters(&params);
     SetupDefaultsForOptionalParams(params);
     AddFormalParamsToScope(&params, current_block_->scope);
     ASSERT(AbstractType::Handle(Z, func.result_type()).IsResolved());
     if (!Function::Handle(func.parent_function()).IsGetterFunction()) {
-      // Parse and discard any formal parameters. They are accessed as
-      // context variables.
-      ParamList discarded_params;
-      ParseFormalParameterList(allow_explicit_default_values,
-                               false,
-                               &discarded_params);
+      // Skip formal parameters. They are accessed as context variables.
+      // Parsing them again (and discarding them) does not work in case of
+      // default values with same name as already parsed formal parameter.
+      SkipToMatchingParenthesis();
     }
   } else if (func.IsAsyncGenClosure()) {
     AddAsyncGenClosureParameters(&params);
     SetupDefaultsForOptionalParams(params);
     AddFormalParamsToScope(&params, current_block_->scope);
     ASSERT(AbstractType::Handle(Z, func.result_type()).IsResolved());
     ASSERT(func.NumParameters() == params.parameters->length());
     if (!Function::Handle(func.parent_function()).IsGetterFunction()) {
-      // Parse and discard any formal parameters. They are accessed as
-      // context variables.
-      ParamList discarded_params;
-      ParseFormalParameterList(allow_explicit_default_values,
-                               false,
-                               &discarded_params);
+      // Skip formal parameters. They are accessed as context variables.
+      // Parsing them again (and discarding them) does not work in case of
+      // default values with same name as already parsed formal parameter.
+      SkipToMatchingParenthesis();
     }
   } else {
     ParseFormalParameterList(allow_explicit_default_values, false, &params);
 
     // The number of parameters and their type are not yet set in local
     // functions, since they are not 'top-level' parsed.
     // However, they are already set when the local function is compiled, since
     // the local function was parsed when its parent was compiled.
     if (func.parameter_types() == Object::empty_array().raw()) {
       AddFormalParamsToFunction(&params, func);
@@ skipping 11145 matching lines @@
 
 
 void Parser::SkipFunctionLiteral() {
   if (IsIdentifier()) {
     if (LookaheadToken(1) != Token::kLPAREN) {
       SkipType(true);
     }
     ExpectIdentifier("function name expected");
   }
   if (CurrentToken() == Token::kLPAREN) {
-    const bool allow_explicit_default_values = true;
-    ParamList params;
-    params.skipped = true;
-    ParseFormalParameterList(allow_explicit_default_values, false, &params);
+    SkipToMatchingParenthesis();
   }
   RawFunction::AsyncModifier async_modifier = ParseFunctionModifier();
   BoolScope allow_await(&this->await_is_keyword_,
                         async_modifier != RawFunction::kNoModifier);
   if (CurrentToken() == Token::kLBRACE) {
     SkipBlock();
     ExpectToken(Token::kRBRACE);
   } else if (CurrentToken() == Token::kARROW) {
     ConsumeToken();
     SkipExpr();
@@ skipping 435 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