fix empty RecogitionException to get syntax error position

Author: numberpi

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/parser/antlr/DescriptiveBailErrorListener.java

@@ -38,14 +38,15 @@
  */
 package com.oracle.graal.python.parser.antlr;
 
-import com.oracle.graal.python.runtime.PythonParser.PIncompleteSourceException;
-import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
-
 import org.antlr.v4.runtime.BaseErrorListener;
 import org.antlr.v4.runtime.RecognitionException;
 import org.antlr.v4.runtime.Recognizer;
+import org.antlr.v4.runtime.Token;
 import org.antlr.v4.runtime.misc.IntervalSet;
 
+import com.oracle.graal.python.runtime.PythonParser.PIncompleteSourceException;
+import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
+
 /**
  * An error listener that immediately bails out of the parse (does not recover) and throws a runtime
  * exception with a descriptive error message.
@@ -73,7 +74,9 @@ public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol,
                 throw handleRecognitionException;
             }
         }
-
+        if (offendingSymbol instanceof Token) {
+            throw new RuntimeException(entireMessage, new EmptyRecognitionException(entireMessage, recognizer, (Token) offendingSymbol));
+        }
         throw new RuntimeException(entireMessage, e);
     }
 
@@ -83,4 +86,19 @@ private static PIncompleteSourceException handleRecognitionException(IntervalSet
         }
         return null;
     }
+
+    private static class EmptyRecognitionException extends RecognitionException {
+        private static final long serialVersionUID = 1L;
+        private Token offendingToken;
+
+        public EmptyRecognitionException(String message, Recognizer<?, ?> recognizer, Token offendingToken) {
+            super(message, recognizer, offendingToken.getInputStream(), null);
+            this.offendingToken = offendingToken;
+        }
+
+        @Override
+        public Token getOffendingToken() {
+            return offendingToken;
+        }
+    }
 }