Debugger: consider try-finally scopes not catching wrt debug events.

src/isolate.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <queue>
 #include "include/v8-debug.h"
 #include "src/allocation.h"
@@ skipping 729 matching lines @@
 
   // Find the correct handler for the current pending exception. This also
   // clears and returns the current pending exception.
   Object* UnwindAndFindHandler();
 
   // Tries to predict whether an exception will be caught. Note that this can
   // only produce an estimate, because it is undecidable whether a finally
   // clause will consume or re-throw an exception. We conservatively assume any
   // finally clause will behave as if the exception were consumed.
   enum CatchType { NOT_CAUGHT, CAUGHT_BY_JAVASCRIPT, CAUGHT_BY_EXTERNAL };
-  CatchType PredictExceptionCatcher();
+  // With the PRECISE mode, try-finally is considered to catch the exception,
+  // as the exception may or may not be rethrown. With the CONSERVATIVE mode,
+  // try-finally is considered to always rethrow. This is to meet the
+  // expectation of the debugger.
+  enum ExceptionPredictionMode { PRECISE_PREDICTION, CONSERVATIVE_PREDICTION };
+  CatchType PredictExceptionCatcher(
+      ExceptionPredictionMode prediction_mode = PRECISE_PREDICTION);

[Michael Starzinger, 2015/05/29 09:00:55]

As discussed offline: The only reason PredictExceptionCatcher exists, is for the
debugger. So if the debugger is only ever interested in the
CONSERVATIVE_PREDICTION, then we could just make that the default and drop the
PRECISE_PREDICTION altogether. WDYT?

 
   void ScheduleThrow(Object* exception);
   // Re-set pending message, script and positions reported to the TryCatch
   // back to the TLS for re-use when rethrowing.
   void RestorePendingMessageFromTryCatch(v8::TryCatch* handler);
   // Un-schedule an exception that was caught by a TryCatch handler.
   void CancelScheduledExceptionFromTryCatch(v8::TryCatch* handler);
   void ReportPendingMessages();
   // Return pending location if any or unfilled structure.
   MessageLocation GetMessageLocation();
@@ skipping 820 matching lines @@
   }
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_