[GR-44053] Do not assume host exception cause has a truffle stack trace.

PullRequest: truffleruby/3661

Author: eregon

src/main/java/org/truffleruby/debug/TruffleDebugNodes.java

@@ -18,6 +18,7 @@
 import java.util.List;
 import java.util.Map;
 
+import com.oracle.truffle.api.TruffleStackTrace;
 import com.oracle.truffle.api.TruffleStackTraceElement;
 import com.oracle.truffle.api.exception.AbstractTruffleException;
 import com.oracle.truffle.api.frame.Frame;
@@ -489,9 +490,11 @@ public abstract static class ThrowJavaExceptionWithCauseNode extends CoreMethodA
         @Specialization(guards = "strings.isRubyString(message)", limit = "1")
         protected Object throwJavaExceptionWithCause(Object message,
                 @Cached RubyStringLibrary strings) {
-            throw new RuntimeException(
-                    RubyGuards.getJavaString(message),
-                    new RuntimeException("cause 1", new RuntimeException("cause 2")));
+            var cause2 = new RuntimeException("cause 2");
+            var cause1 = new RuntimeException("cause 1", cause2);
+            TruffleStackTrace.fillIn(cause2);
+            TruffleStackTrace.fillIn(cause1);
+            throw new RuntimeException(RubyGuards.getJavaString(message), cause1);
         }
 
     }

src/main/java/org/truffleruby/language/backtrace/BacktraceFormatter.java

@@ -421,7 +421,10 @@ public static void printInternalError(RubyContext context, Throwable throwable,
                     printJavaStackTrace(stream, t);
 
                     if (TruffleStackTrace.getStackTrace(t) != null) {
-                        stream.println(formatter.formatBacktrace(null, new Backtrace(t)));
+                        var formatted = formatter.formatBacktrace(null, new Backtrace(t));
+                        if (!formatted.isEmpty()) {
+                            stream.println(formatted);
+                        }
                     }
                 }
             }