bpo-29622: Make AST constructor to accept less than enough number of positional argum...

bpo-29463 added optional "docstring" field to 4 AST types.
While it is optional, it breaks backward compatibility because AST constructor
requires number of positional argument is same to number of fields.

AST types accepts empty arguments, and incomplete keyword arguments.
But it's not big problem because field can be filled after creation, and checked when compiling.
So stop requiring complete set of fields for positional arguments too.

diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index ac79989796d6a4bb58f6c1e381d2e8cde54d2073..366269fe405aa94438b2c535be886f07f931d037 100644 (file)
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -373,12 +373,8 @@ class AST_Tests(unittest.TestCase):
         self.assertEqual(x.right, 3)
         self.assertEqual(x.lineno, 0)
 
-        # node raises exception when not given enough arguments
-        self.assertRaises(TypeError, ast.BinOp, 1, 2)
         # node raises exception when given too many arguments
         self.assertRaises(TypeError, ast.BinOp, 1, 2, 3, 4)
-        # node raises exception when not given enough arguments
-        self.assertRaises(TypeError, ast.BinOp, 1, 2, lineno=0)
         # node raises exception when given too many arguments
         self.assertRaises(TypeError, ast.BinOp, 1, 2, 3, 4, lineno=0)
 

diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 444cdea341d78b50a0100b06409ee7f8601a7c56..096f5f8c7494f73b43ac89e4ac4a5729469fa4f2 100644 (file)
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -664,29 +664,27 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
         if (numfields == -1)
             goto cleanup;
     }
+
     res = 0; /* if no error occurs, this stays 0 to the end */
-    if (PyTuple_GET_SIZE(args) > 0) {
-        if (numfields != PyTuple_GET_SIZE(args)) {
-            PyErr_Format(PyExc_TypeError, "%.400s constructor takes %s"
-                         "%zd positional argument%s",
-                         Py_TYPE(self)->tp_name,
-                         numfields == 0 ? "" : "either 0 or ",
-                         numfields, numfields == 1 ? "" : "s");
+    if (numfields < PyTuple_GET_SIZE(args)) {
+        PyErr_Format(PyExc_TypeError, "%.400s constructor takes at most "
+                     "%zd positional argument%s",
+                     Py_TYPE(self)->tp_name,
+                     numfields, numfields == 1 ? "" : "s");
+        res = -1;
+        goto cleanup;
+    }
+    for (i = 0; i < PyTuple_GET_SIZE(args); i++) {
+        /* cannot be reached when fields is NULL */
+        PyObject *name = PySequence_GetItem(fields, i);
+        if (!name) {
             res = -1;
             goto cleanup;
         }
-        for (i = 0; i < PyTuple_GET_SIZE(args); i++) {
-            /* cannot be reached when fields is NULL */
-            PyObject *name = PySequence_GetItem(fields, i);
-            if (!name) {
-                res = -1;
-                goto cleanup;
-            }
-            res = PyObject_SetAttr(self, name, PyTuple_GET_ITEM(args, i));
-            Py_DECREF(name);
-            if (res < 0)
-                goto cleanup;
-        }
+        res = PyObject_SetAttr(self, name, PyTuple_GET_ITEM(args, i));
+        Py_DECREF(name);
+        if (res < 0)
+            goto cleanup;
     }
     if (kw) {
         i = 0;  /* needed by PyDict_Next */

diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index a6a49f78b1e2491882b3a42c9369666ed45da278..2759b2fe9c4b33fa2470e6391f695257984edf24 100644 (file)
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -551,29 +551,27 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
         if (numfields == -1)
             goto cleanup;
     }
+
     res = 0; /* if no error occurs, this stays 0 to the end */
-    if (PyTuple_GET_SIZE(args) > 0) {
-        if (numfields != PyTuple_GET_SIZE(args)) {
-            PyErr_Format(PyExc_TypeError, "%.400s constructor takes %s"
-                         "%zd positional argument%s",
-                         Py_TYPE(self)->tp_name,
-                         numfields == 0 ? "" : "either 0 or ",
-                         numfields, numfields == 1 ? "" : "s");
+    if (numfields < PyTuple_GET_SIZE(args)) {
+        PyErr_Format(PyExc_TypeError, "%.400s constructor takes at most "
+                     "%zd positional argument%s",
+                     Py_TYPE(self)->tp_name,
+                     numfields, numfields == 1 ? "" : "s");
+        res = -1;
+        goto cleanup;
+    }
+    for (i = 0; i < PyTuple_GET_SIZE(args); i++) {
+        /* cannot be reached when fields is NULL */
+        PyObject *name = PySequence_GetItem(fields, i);
+        if (!name) {
             res = -1;
             goto cleanup;
         }
-        for (i = 0; i < PyTuple_GET_SIZE(args); i++) {
-            /* cannot be reached when fields is NULL */
-            PyObject *name = PySequence_GetItem(fields, i);
-            if (!name) {
-                res = -1;
-                goto cleanup;
-            }
-            res = PyObject_SetAttr(self, name, PyTuple_GET_ITEM(args, i));
-            Py_DECREF(name);
-            if (res < 0)
-                goto cleanup;
-        }
+        res = PyObject_SetAttr(self, name, PyTuple_GET_ITEM(args, i));
+        Py_DECREF(name);
+        if (res < 0)
+            goto cleanup;
     }
     if (kw) {
         i = 0;  /* needed by PyDict_Next */