Properly reset external catcher if exception couldn't be externally caught.

We can wrongly assume that exception which is not intended to be caught
by external try/catch should be caught if this exception inherits
external catcher from some previous exception.  To prevent that,
clear external catcher when processing exceptions which cannot be
externally caught.

BUG=v8:1184
TEST=test/mjsunit/regress/regress-1184.js

Review URL: http://codereview.chromium.org/6538081

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6905 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/top.cc

@@ -735,9 +735,8 @@ Failure* Top::ReThrow(MaybeObject* exception, MessageLocation* location) {
   bool can_be_caught_externally = false;
   ShouldReportException(&can_be_caught_externally,
                         is_catchable_by_javascript(exception));
-  if (can_be_caught_externally) {
-    thread_local_.catcher_ = try_catch_handler();
-  }
+  thread_local_.catcher_ = can_be_caught_externally ?
+      try_catch_handler() : NULL;
 
   // Set the exception being re-thrown.
   set_pending_exception(exception);
@@ -913,9 +912,10 @@ void Top::DoThrow(MaybeObject* exception,
     }
   }
 
-  if (can_be_caught_externally) {
-    thread_local_.catcher_ = try_catch_handler();
-  }
+  // Do not forget to clean catcher_ if currently thrown exception cannot
+  // be caught.  If necessary, ReThrow will update the catcher.
+  thread_local_.catcher_ = can_be_caught_externally ?
+      try_catch_handler() : NULL;
 
   // NOTE: Notifying the debugger or generating the message
   // may have caused new exceptions. For now, we just ignore

test/mjsunit/regress/regress-1184.js

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test the case when finally clause throws another exception (stack overflow)
+// which goes through some try/catch block---we need to clear v8::TryCatch
+// catcher as it doesn't catch original exception any more.
+
+o = {};
+o.__defineGetter__('foo', function() { throw 42; });
+function f() {
+ try {
+   // throw below sets up Top::thread_local_.catcher_...
+   throw 42;
+ } finally {
+   // ...JS accessor traverses v8 runtime/JS boundary and
+   // when coming back from JS to v8 runtime, retraverses
+   // stack with catcher set while processing exception
+   // which is not caught by external try catch.
+   try { o.foo; } catch(e) { };
+   return;
+ }
+};
+f();