Handle slice at end of list as append

Fixes jython#356

Author: jeff5

Lib/test/test_ast_jy.py

@@ -146,10 +146,33 @@ def test_empty_init(self):
         #ast.stmt()
         #ast.unaryop()
 
+class TestAstList(unittest.TestCase):
+    """Supplementary tests for org.python.core.AstList"""
+
+    def test_concat(self):
+        # Issue gh-356 Java IndexOOB error on append
+        body = ast.parse('x=1').body    # _ast.AstList
+        p = [ast.Pass()]                # PyList
+        x = body + p
+        self.assertEqual(2, len(x))
+        self.assertIsInstance(x[1], ast.Pass)
+
+    def test_append(self):
+        # Issue gh-356 Java IndexOOB error on append
+        body = ast.parse('x=1').body    # _ast.AstList
+        p = [ast.Pass()]                # PyList
+        body += p
+        self.assertEqual(2, len(body))
+        self.assertIsInstance(body[1], ast.Pass)
+
+
 #==============================================================================
 
 def test_main(verbose=None):
-    test_classes = [TestCompile]
+    test_classes = [
+        TestCompile,
+        TestAstList
+    ]
     test_support.run_unittest(*test_classes)
 
 if __name__ == "__main__":

src/org/python/core/AstList.java

@@ -493,9 +493,14 @@ protected void setslicePySequence(int start, int stop, int step, PySequence valu
                 }
                 value = newseq;
             }
-            int n = value.__len__();
+            int size = __len__(), n = value.__len__();
             for (int i = 0, j = start; i < n; i++, j += step) {
-                pyset(j, value.pyget(i));
+                PyObject item = value.pyget(i);
+                if (j < size) {
+                    pyset(j, item);
+                } else {
+                    pyadd(item);
+                }
             }
         }
     }