Improve implementation of 'PySequence_Fast'.

Author: fangerer

graalpython/com.oracle.graal.python.cext/src/abstract.c

@@ -256,9 +256,26 @@ PyObject* PySequence_Tuple(PyObject *v) {
     return UPCALL_CEXT_O(_jls_PySequence_Tuple, native_to_java(v));
 }
 
-UPCALL_ID(PySequence_Fast);
+UPCALL_ID(PySequence_List);
+PyObject* PySequence_List(PyObject *v) {
+    return UPCALL_CEXT_O(_jls_PySequence_List, native_to_java(v));
+}
+
 PyObject * PySequence_Fast(PyObject *v, const char *m) {
-    return UPCALL_CEXT_O(_jls_PySequence_Fast, native_to_java(v), polyglot_from_string(m, SRC_CS));
+    if (v == NULL) {
+        return null_error();
+    }
+
+    if (PyList_CheckExact(v) || PyTuple_CheckExact(v)) {
+        Py_INCREF(v);
+        return v;
+    }
+
+	PyObject* result = UPCALL_CEXT_O(_jls_PySequence_List, native_to_java(v));
+	if (result == NULL) {
+		PyErr_SetString(PyExc_TypeError, m);
+	}
+	return result;
 }
 
 UPCALL_ID(PyObject_GetItem);

graalpython/lib-graalpython/python_cext.py

@@ -517,13 +517,8 @@ def PySequence_Tuple(obj):
 
 
 @may_raise
-def PySequence_Fast(obj, msg):
-    if isinstance(obj, tuple) or isinstance(obj, list):
-        return obj
-    try:
-        return list(obj)
-    except TypeError:
-        raise TypeError(msg)
+def PySequence_List(obj):
+    return list(obj)
 
 
 def PySequence_Check(obj):