Make a copy of the Backtrace and RaiseException when copying a Ruby exception

* To maintain a 1-1-1 relationship.

Author: eregon

spec/tags/core/exception/exception_tags.txt

@@ -77,7 +77,12 @@ public Object initializeCopySelfIsSameAsFrom(DynamicObject self, DynamicObject f
 
         @Specialization(guards = { "self != from", "isRubyException(from)" })
         public Object initializeCopy(DynamicObject self, DynamicObject from) {
-            Layouts.EXCEPTION.setBacktrace(self, Layouts.EXCEPTION.getBacktrace(from));
+            Backtrace backtrace = Layouts.EXCEPTION.getBacktrace(from);
+            if (backtrace != null) {
+                Layouts.EXCEPTION.setBacktrace(self, backtrace.copy(getContext(), self));
+            } else {
+                Layouts.EXCEPTION.setBacktrace(self, backtrace);
+            }
             Layouts.EXCEPTION.setFormatter(self, Layouts.EXCEPTION.getFormatter(from));
             Layouts.EXCEPTION.setMessage(self, Layouts.EXCEPTION.getMessage(from));
 

src/main/java/org/truffleruby/core/exception/ExceptionNodes.java

@@ -44,6 +44,20 @@ public Backtrace(Node location, SourceSection sourceLocation, int omitted, Throw
         this.javaThrowable = javaThrowable;
     }
 
+    public Backtrace copy(RubyContext context, DynamicObject exception) {
+        Backtrace copy = new Backtrace(location, sourceLocation, omitted, javaThrowable);
+        // A Backtrace is 1-1-1 with a RaiseException and a Ruby exception
+        RaiseException newRaiseException = new RaiseException(context, exception, this.raiseException.isInternalError());
+        // Copy the TruffleStackTrace
+        TruffleStackTraceElement.fillIn(this.raiseException);
+        assert this.raiseException.getCause() != null;
+        newRaiseException.initCause(this.raiseException.getCause());
+        // Another way would be to copy the activations (copy.activations = getActivations()), but
+        // then the TruffleStrackTrace would be inconsistent.
+        copy.setRaiseException(newRaiseException);
+        return copy;
+    }
+
     public Node getLocation() {
         return location;
     }