Rethrow the existing TruffleException if there is one in #raise to pr…

…eserve the backtrace

* Fixes #1459.

CHANGELOG.md

@@ -17,6 +17,7 @@ Bug fixes:
 * `ArgumentError` messages now better match MRI (#1467).
 * Added support for `:float_millisecond`, `:millisecond`, and
   `:second` time units to `Process.clock_gettime` (#1468).
+* Fixed backtrace of re-raised exceptions (#1459).
 
 Changes:
 

src/main/java/org/truffleruby/core/VMPrimitiveNodes.java

@@ -63,6 +63,7 @@
 import org.truffleruby.core.rope.CodeRange;
 import org.truffleruby.core.string.StringNodes;
 import org.truffleruby.core.string.StringOperations;
+import org.truffleruby.language.backtrace.Backtrace;
 import org.truffleruby.language.control.ExitException;
 import org.truffleruby.language.control.RaiseException;
 import org.truffleruby.language.control.ThrowException;
@@ -214,8 +215,16 @@ public Object vmObjectClass(Object object) {
     public static abstract class VMRaiseExceptionPrimitiveNode extends PrimitiveArrayArgumentsNode {
 
         @Specialization(guards = "isRubyException(exception)")
-        public DynamicObject vmRaiseException(DynamicObject exception, boolean internal) {
-            throw new RaiseException(getContext(), exception, internal);
+        public DynamicObject vmRaiseException(DynamicObject exception, boolean internal,
+                @Cached("createBinaryProfile()") ConditionProfile reRaiseProfile) {
+            final Backtrace backtrace = Layouts.EXCEPTION.getBacktrace(exception);
+            if (reRaiseProfile.profile(backtrace != null && backtrace.getTruffleException() != null)) {
+                // We need to rethrow the existing TruffleException, otherwise we would lose the
+                // incremental backtrace accumulated in it.
+                throw (RaiseException) backtrace.getTruffleException();
+            } else {
+                throw new RaiseException(getContext(), exception, internal);
+            }
         }
 
     }