Fix cacthing exception object: a null exception is always caught.

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/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 4902 matching lines @@
     if (!exception_param.type->IsDynamicType()) {  // Has a type specification.
       // Now form an 'if type check' as an exception type exists in
       // the catch specifier.
       if (!exception_param.type->IsInstantiated() &&
           (current_block_->scope->function_level() > 0)) {
         // Make sure that the instantiator is captured.
         CaptureReceiver();
       }
       AstNode* exception_type = new TypeNode(catch_pos, *exception_param.type);
       AstNode* exception_var = new LoadLocalNode(catch_pos, *catch_excp_var);
-      AstNode* cond_expr = new ComparisonNode(
+      // Null is also allowed.
+      AstNode* null_literal =
+          new LiteralNode(catch_pos, Instance::ZoneHandle(Instance::null()));
+      AstNode* null_cond_expr = new ComparisonNode(
+          catch_pos, Token::kEQ_STRICT, exception_var, null_literal);
+      AstNode* type_cond_expr = new ComparisonNode(
           catch_pos, Token::kIS, exception_var, exception_type);
+      AstNode* or_node = new BinaryOpNode(
+          catch_pos, Token::kOR, null_cond_expr, type_cond_expr);

[hausner, 2012/02/21 21:46:41]

As discussed offline, this compare has to be done only once in the first catch
clause.

[srdjan, 2012/02/21 21:53:52]

Done.

       current_block_->statements->Add(
-          new IfNode(catch_pos, cond_expr, catch_handler, NULL));
+          new IfNode(catch_pos, or_node, catch_handler, NULL));
     } else {
       // No exception type exists in the catch specifier so execute the
       // catch handler code unconditionally.
       current_block_->statements->Add(catch_handler);
       generic_catch_seen = true;
     }
     catch_clause = CloseBlock();
 
     // Add this individual catch handler to the catch handlers list.
     current_block_->statements->Add(catch_clause);
@@ skipping 2910 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart