bpo-29622: Make AST constructor to accept less than enough number of …

…positional arguments (pythonGH-249) 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.
danchr · Feb 23, 2017 · 4c78c52 · 4c78c52
1 parent 561ca80
commit 4c78c52
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Showing 3 changed files with 34 additions and 42 deletions.
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
@@ -373,12 +373,8 @@ def test_nodeclasses(self):
         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
@@ -664,29 +664,27 @@ def visitModule(self, mod):
         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
@@ -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 */