Fix yield statements in catch blocks

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 43705)
+++ runtime/vm/parser.cc	(working copy)
@@ -3171,7 +3171,7 @@
   } else if (func.IsSyncGenClosure()) {
     // The closure containing the body of a sync generator is debuggable.
     ASSERT(func.is_debuggable());
-    // Nothing special to do.
+    async_temp_scope_ = current_block_->scope;
   }
 
   BoolScope allow_await(&this->await_is_keyword_,
@@ -5975,8 +5975,11 @@
   }
 
   ASSERT(try_blocks_list_ != NULL);
+  ASSERT(innermost_function().IsAsyncClosure() ||
+         innermost_function().IsAsyncFunction());
   if (innermost_function().IsAsyncClosure() ||
       innermost_function().IsAsyncFunction()) {
+    // This should always be true here.

[regis, 2015/02/11 23:53:44]

Add a TODO if you want to revisit this code. Otherwise, remove the if statement
that duplicates the assert.

[hausner, 2015/02/12 00:18:50]

Removed the if. The assertion never fired in our tests.

     if ((try_blocks_list_->outer_try_block() != NULL) &&
         (try_blocks_list_->outer_try_block()->try_block()
             ->scope->function_level() ==
@@ -6081,7 +6084,9 @@
   PushTryBlock(current_block_);
 
   if (innermost_function().IsAsyncClosure() ||
-      innermost_function().IsAsyncFunction()) {
+      innermost_function().IsAsyncFunction() ||
+      innermost_function().IsSyncGenClosure() ||
+      innermost_function().IsSyncGenerator()) {
     SetupSavedTryContext(context_var);
   }
 }
@@ -6164,10 +6169,7 @@
   OpenFunctionBlock(body);
   AddFormalParamsToScope(&closure_params, current_block_->scope);
   OpenBlock();
-
-  /*
-  async_temp_scope_ = current_block_->scope; // Is this needed?
-  */
+  async_temp_scope_ = current_block_->scope;
   return body.raw();
 }
 
@@ -8196,7 +8198,9 @@
   // outer try block (if it exists).  The current try block has already been
   // removed from the stack of try blocks.
   if ((innermost_function().IsAsyncClosure() ||
-       innermost_function().IsAsyncFunction()) &&
+       innermost_function().IsAsyncFunction() ||
+       innermost_function().IsSyncGenClosure() ||
+       innermost_function().IsSyncGenerator()) &&
       (try_blocks_list_ != NULL)) {
     // We need two unchain two scopes: finally clause, and the try block level.
     RestoreSavedTryContext(current_block_->scope->parent()->parent(),
@@ -8356,7 +8360,9 @@
     // outer try block (if it exists).
     ASSERT(try_blocks_list_ != NULL);
     if (innermost_function().IsAsyncClosure() ||
-        innermost_function().IsAsyncFunction()) {
+        innermost_function().IsAsyncFunction() ||
+        innermost_function().IsSyncGenClosure() ||
+        innermost_function().IsSyncGenerator()) {
       if ((try_blocks_list_->outer_try_block() != NULL) &&
           (try_blocks_list_->outer_try_block()->try_block()
               ->scope->function_level() ==
@@ -8464,7 +8470,9 @@
     // outer try block (if it exists).
     ASSERT(try_blocks_list_ != NULL);
     if (innermost_function().IsAsyncClosure() ||
-        innermost_function().IsAsyncFunction()) {
+        innermost_function().IsAsyncFunction() ||
+        innermost_function().IsSyncGenClosure() ||
+        innermost_function().IsSyncGenerator()) {
       if ((try_blocks_list_->outer_try_block() != NULL) &&
           (try_blocks_list_->outer_try_block()->try_block()
               ->scope->function_level() ==
@@ -8495,6 +8503,7 @@
       Scanner::kNoSourcePos,
       async_saved_try_ctx_name,
       Type::ZoneHandle(Z, Type::DynamicType()));
+  ASSERT(async_temp_scope_ != NULL);
   async_temp_scope_->AddVariable(async_saved_try_ctx);
   async_saved_try_ctx->set_is_captured();
   async_saved_try_ctx = current_block_->scope->LookupVariable(
@@ -8600,7 +8609,9 @@
   ExpectToken(Token::kLBRACE);
 
   if (innermost_function().IsAsyncClosure() ||
-      innermost_function().IsAsyncFunction()) {
+      innermost_function().IsAsyncFunction() ||
+      innermost_function().IsSyncGenClosure() ||
+      innermost_function().IsSyncGenerator()) {
     SetupSavedTryContext(context_var);
   }
 
@@ -8842,6 +8853,22 @@
         new(Z) LiteralNode(TokenPos(), Bool::True()));
     return_true->set_return_type(ReturnNode::kContinuationTarget);
     yield->AddNode(return_true);
+
+    // If this expression is part of a try block, also append the code for
+    // restoring the saved try context that lives on the stack.
+    const String& async_saved_try_ctx_name =
+        String::Handle(Z, parsed_function()->async_saved_try_ctx_name());
+    if (!async_saved_try_ctx_name.IsNull()) {
+      LocalVariable* async_saved_try_ctx =
+          current_block_->scope->LookupVariable(async_saved_try_ctx_name,
+                                                false);
+      ASSERT(async_saved_try_ctx != NULL);
+      yield->AddNode(new (Z) StoreLocalNode(
+          Scanner::kNoSourcePos,
+          parsed_function()->saved_try_ctx(),
+          new (Z) LoadLocalNode(Scanner::kNoSourcePos, async_saved_try_ctx)));
+    }
+
     statement = yield;
     ExpectSemicolon();
   } else if (token == Token::kIF) {