No returns allowed in constructors

runtime/vm/parser.cc

 // Copyright (c) 2011, 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/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 1752 matching lines @@
       current_block_->statements->Add(
           new StaticCallNode(token_index_, super_ctor, super_call_args));
     }
   }
   if (CurrentToken() == Token::kLBRACE) {
     ConsumeToken();
     ParseStatementSequence();
     ExpectToken(Token::kRBRACE);
   } else if (CurrentToken() == Token::kARROW) {
     ConsumeToken();
+    if (func.IsConstructor()) {
+      ErrorMsg("constructors may not return a value");
+    }
     intptr_t expr_pos = token_index_;
     AstNode* expr = ParseExpr(kAllowConst);
     ASSERT(expr != NULL);
     current_block_->statements->Add(new ReturnNode(expr_pos, expr));
   } else if (IsLiteral("native")) {
     ParseNativeFunctionBlock(&params, func);
   } else if (CurrentToken() == Token::kSEMICOLON) {
     ConsumeToken();
     ASSERT(func.IsConstructor());
     // Some constructors have no function body.
@@ skipping 3048 matching lines @@
     statement = ParseWhileStatement(label_name);
   } else if (CurrentToken() == Token::kFOR) {
     statement = ParseForStatement(label_name);
   } else if (CurrentToken() == Token::kDO) {
     statement = ParseDoWhileStatement(label_name);
   } else if (CurrentToken() == Token::kSWITCH) {
     statement = ParseSwitchStatement(label_name);
   } else if (CurrentToken() == Token::kTRY) {
     statement = ParseTryStatement(label_name);
   } else if (CurrentToken() == Token::kRETURN) {
+    const intptr_t return_pos = token_index_;
     ConsumeToken();
     if (CurrentToken() != Token::kSEMICOLON) {
+      if (current_function().IsConstructor() &&
+          (current_block_->scope->function_level() == 0)) {
+        ErrorMsg(return_pos, "return of a value not allowed in constructors");
+      }
       AstNode* expr = ParseExpr(kAllowConst);
       statement = new ReturnNode(statement_pos, expr);
     } else {
       statement = new ReturnNode(statement_pos);
     }
     AddNodeForFinallyInlining(statement);
     ExpectSemicolon();
   } else if (CurrentToken() == Token::kIF) {
     statement = ParseIfStatement(label_name);
   } else if (CurrentToken() == Token::kASSERT) {
@@ skipping 2346 matching lines @@
 }
 
 
 void Parser::SkipNestedExpr() {
   const bool saved_mode = SetAllowFunctionLiterals(true);
   SkipExpr();
   SetAllowFunctionLiterals(saved_mode);
 }
 
 }  // namespace dart