[GR-20955] Fix python try grammar

PullRequest: graalpython/883

Author: qunaibit

graalpython/com.oracle.graal.python.test/src/com/oracle/graal/python/test/grammar/TryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2018, Oracle and/or its affiliates.
+ * Copyright (c) 2017, 2020, Oracle and/or its affiliates.
  * Copyright (c) 2013, Regents of the University of California
  *
  * All rights reserved.
@@ -27,6 +27,7 @@
 
 import org.junit.Test;
 
+import static com.oracle.graal.python.test.PythonTests.assertLastLineErrorContains;
 import static com.oracle.graal.python.test.PythonTests.assertPrints;
 
 public class TryTests {
@@ -185,4 +186,10 @@ public void tupleExceptTypes() {
 
         assertPrints("", source);
     }
+
+    @Test
+    public void tryGrammarError() {
+        assertLastLineErrorContains("SyntaxError", "try: 1+1\n");
+        assertLastLineErrorContains("SyntaxError", "try:\n 1+1\n");
+    }
 }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/parser/antlr/Python3.g4

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2019, Oracle and/or its affiliates.
+ * Copyright (c) 2017-2020, Oracle and/or its affiliates.
  * Copyright (c) 2014 by Bart Kiers
  *
  * The MIT License (MIT)
@@ -887,11 +887,11 @@ try_stmt
             SSTNode finallyStatement = null; 
         }
 	(
-		( except_clause 
-                    { push($except_clause.result); } )+
+		( except_clause { push($except_clause.result); } )+
 		( 'else' ':' suite { elseStatement = $suite.result; } )?
-	)?
-	( 'finally' ':' suite { finallyStatement = $suite.result; } )?
+		( 'finally' ':' suite { finallyStatement = $suite.result; } )? |
+		  'finally' ':' suite { finallyStatement = $suite.result; }
+	)
 	{ push(new TrySSTNode($body.result, getArray(start, ExceptSSTNode[].class), elseStatement, finallyStatement, getStartIndex($ctx), getLastIndex($ctx))); }
 ;