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[3.14] gh-133783: Fix __replace__ on AST nodes for optional attributes (GH-133797) (#133842)
gh-133783: Fix __replace__ on AST nodes for optional attributes (GH-133797) (cherry picked from commit 7dddb4e) Co-authored-by: Jelle Zijlstra <[email protected]>
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Lib/test/test_ast/test_ast.py

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@@ -1315,6 +1315,15 @@ def test_replace_reject_missing_field(self):
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self.assertIs(repl.id, 'y')
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self.assertIs(repl.ctx, context)
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def test_replace_accept_missing_field_with_default(self):
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node = ast.FunctionDef(name="foo", args=ast.arguments())
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self.assertIs(node.returns, None)
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self.assertEqual(node.decorator_list, [])
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node2 = copy.replace(node, name="bar")
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self.assertEqual(node2.name, "bar")
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self.assertIs(node2.returns, None)
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self.assertEqual(node2.decorator_list, [])
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def test_replace_reject_known_custom_instance_fields_commits(self):
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node = ast.parse('x').body[0].value
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node.extra = extra = object() # add instance 'extra' field
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@@ -0,0 +1,3 @@
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Fix bug with applying :func:`copy.replace` to :mod:`ast` objects. Attributes
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that default to ``None`` were incorrectly treated as required for manually
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created AST nodes.

Parser/asdl_c.py

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@@ -1244,6 +1244,32 @@ def visitModule(self, mod):
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Py_DECREF(unused);
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}
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}
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// Discard fields from 'expecting' that default to None
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PyObject *field_types = NULL;
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if (PyObject_GetOptionalAttr((PyObject*)Py_TYPE(self),
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&_Py_ID(_field_types),
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&field_types) < 0)
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{
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Py_DECREF(expecting);
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return -1;
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}
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if (field_types != NULL) {
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Py_ssize_t pos = 0;
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PyObject *field_name, *field_type;
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while (PyDict_Next(field_types, &pos, &field_name, &field_type)) {
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if (_PyUnion_Check(field_type)) {
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// optional field
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if (PySet_Discard(expecting, field_name) < 0) {
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Py_DECREF(expecting);
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Py_DECREF(field_types);
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return -1;
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}
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}
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}
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Py_DECREF(field_types);
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}
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// Now 'expecting' contains the fields or attributes
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// that would not be filled inside ast_type_replace().
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Py_ssize_t m = PySet_GET_SIZE(expecting);

Python/Python-ast.c

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