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-rw-r--r--Doc/library/ast.rst14
-rw-r--r--Doc/whatsnew/3.13.rst6
-rw-r--r--Lib/test/test_ast.py41
-rw-r--r--Misc/NEWS.d/next/Library/2024-04-23-21-17-00.gh-issue-117486.ea3KYD.rst4
-rwxr-xr-xParser/asdl_c.py31
-rw-r--r--Python/Python-ast.c31
6 files changed, 94 insertions, 33 deletions
diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst
index e954c38..02dc7c8 100644
--- a/Doc/library/ast.rst
+++ b/Doc/library/ast.rst
@@ -61,7 +61,7 @@ Node classes
.. attribute:: _fields
- Each concrete class has an attribute :attr:`_fields` which gives the names
+ Each concrete class has an attribute :attr:`!_fields` which gives the names
of all child nodes.
Each instance of a concrete class has one attribute for each child node,
@@ -74,6 +74,18 @@ Node classes
as Python lists. All possible attributes must be present and have valid
values when compiling an AST with :func:`compile`.
+ .. attribute:: _field_types
+
+ The :attr:`!_field_types` attribute on each concrete class is a dictionary
+ mapping field names (as also listed in :attr:`_fields`) to their types.
+
+ .. doctest::
+
+ >>> ast.TypeVar._field_types
+ {'name': <class 'str'>, 'bound': ast.expr | None, 'default_value': ast.expr | None}
+
+ .. versionadded:: 3.13
+
.. attribute:: lineno
col_offset
end_lineno
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index 43934ba..c82d8bd 100644
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -384,6 +384,12 @@ ast
argument that does not map to a field on the AST node is now deprecated,
and will raise an exception in Python 3.15.
+ These changes do not apply to user-defined subclasses of :class:`ast.AST`,
+ unless the class opts in to the new behavior by setting the attribute
+ :attr:`ast.AST._field_types`.
+
+ (Contributed by Jelle Zijlstra in :gh:`105858` and :gh:`117486`.)
+
* :func:`ast.parse` now accepts an optional argument *optimize*
which is passed on to the :func:`compile` built-in. This makes it
possible to obtain an optimized AST.
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index 6d05c8f..f6e22d4 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -3036,7 +3036,7 @@ class ASTConstructorTests(unittest.TestCase):
self.assertEqual(node.name, 'foo')
self.assertEqual(node.decorator_list, [])
- def test_custom_subclass(self):
+ def test_custom_subclass_with_no_fields(self):
class NoInit(ast.AST):
pass
@@ -3044,17 +3044,17 @@ class ASTConstructorTests(unittest.TestCase):
self.assertIsInstance(obj, NoInit)
self.assertEqual(obj.__dict__, {})
+ def test_fields_but_no_field_types(self):
class Fields(ast.AST):
_fields = ('a',)
- with self.assertWarnsRegex(DeprecationWarning,
- r"Fields provides _fields but not _field_types."):
- obj = Fields()
+ obj = Fields()
with self.assertRaises(AttributeError):
obj.a
obj = Fields(a=1)
self.assertEqual(obj.a, 1)
+ def test_fields_and_types(self):
class FieldsAndTypes(ast.AST):
_fields = ('a',)
_field_types = {'a': int | None}
@@ -3065,6 +3065,7 @@ class ASTConstructorTests(unittest.TestCase):
obj = FieldsAndTypes(a=1)
self.assertEqual(obj.a, 1)
+ def test_fields_and_types_no_default(self):
class FieldsAndTypesNoDefault(ast.AST):
_fields = ('a',)
_field_types = {'a': int}
@@ -3077,6 +3078,38 @@ class ASTConstructorTests(unittest.TestCase):
obj = FieldsAndTypesNoDefault(a=1)
self.assertEqual(obj.a, 1)
+ def test_incomplete_field_types(self):
+ class MoreFieldsThanTypes(ast.AST):
+ _fields = ('a', 'b')
+ _field_types = {'a': int | None}
+ a: int | None = None
+ b: int | None = None
+
+ with self.assertWarnsRegex(
+ DeprecationWarning,
+ r"Field 'b' is missing from MoreFieldsThanTypes\._field_types"
+ ):
+ obj = MoreFieldsThanTypes()
+ self.assertIs(obj.a, None)
+ self.assertIs(obj.b, None)
+
+ obj = MoreFieldsThanTypes(a=1, b=2)
+ self.assertEqual(obj.a, 1)
+ self.assertEqual(obj.b, 2)
+
+ def test_complete_field_types(self):
+ class _AllFieldTypes(ast.AST):
+ _fields = ('a', 'b')
+ _field_types = {'a': int | None, 'b': list[str]}
+ # This must be set explicitly
+ a: int | None = None
+ # This will add an implicit empty list default
+ b: list[str]
+
+ obj = _AllFieldTypes()
+ self.assertIs(obj.a, None)
+ self.assertEqual(obj.b, [])
+
@support.cpython_only
class ModuleStateTests(unittest.TestCase):
diff --git a/Misc/NEWS.d/next/Library/2024-04-23-21-17-00.gh-issue-117486.ea3KYD.rst b/Misc/NEWS.d/next/Library/2024-04-23-21-17-00.gh-issue-117486.ea3KYD.rst
new file mode 100644
index 0000000..f02d895
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-04-23-21-17-00.gh-issue-117486.ea3KYD.rst
@@ -0,0 +1,4 @@
+Improve the behavior of user-defined subclasses of :class:`ast.AST`. Such
+classes will now require no changes in the usual case to conform with the
+behavior changes of the :mod:`ast` module in Python 3.13. Patch by Jelle
+Zijlstra.
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 1f0be45..11d59fa 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -979,14 +979,9 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
goto cleanup;
}
if (field_types == NULL) {
- if (PyErr_WarnFormat(
- PyExc_DeprecationWarning, 1,
- "%.400s provides _fields but not _field_types. "
- "This will become an error in Python 3.15.",
- Py_TYPE(self)->tp_name
- ) < 0) {
- res = -1;
- }
+ // Probably a user-defined subclass of AST that lacks _field_types.
+ // This will continue to work as it did before 3.13; i.e., attributes
+ // that are not passed in simply do not exist on the instance.
goto cleanup;
}
remaining_list = PySequence_List(remaining_fields);
@@ -997,12 +992,21 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
PyObject *name = PyList_GET_ITEM(remaining_list, i);
PyObject *type = PyDict_GetItemWithError(field_types, name);
if (!type) {
- if (!PyErr_Occurred()) {
- PyErr_SetObject(PyExc_KeyError, name);
+ if (PyErr_Occurred()) {
+ goto set_remaining_cleanup;
+ }
+ else {
+ if (PyErr_WarnFormat(
+ PyExc_DeprecationWarning, 1,
+ "Field '%U' is missing from %.400s._field_types. "
+ "This will become an error in Python 3.15.",
+ name, Py_TYPE(self)->tp_name
+ ) < 0) {
+ goto set_remaining_cleanup;
+ }
}
- goto set_remaining_cleanup;
}
- if (_PyUnion_Check(type)) {
+ else if (_PyUnion_Check(type)) {
// optional field
// do nothing, we'll have set a None default on the class
}
@@ -1026,8 +1030,7 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
"This will become an error in Python 3.15.",
Py_TYPE(self)->tp_name, name
) < 0) {
- res = -1;
- goto cleanup;
+ goto set_remaining_cleanup;
}
}
}
diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 1953142..4956d04 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -5178,14 +5178,9 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
goto cleanup;
}
if (field_types == NULL) {
- if (PyErr_WarnFormat(
- PyExc_DeprecationWarning, 1,
- "%.400s provides _fields but not _field_types. "
- "This will become an error in Python 3.15.",
- Py_TYPE(self)->tp_name
- ) < 0) {
- res = -1;
- }
+ // Probably a user-defined subclass of AST that lacks _field_types.
+ // This will continue to work as it did before 3.13; i.e., attributes
+ // that are not passed in simply do not exist on the instance.
goto cleanup;
}
remaining_list = PySequence_List(remaining_fields);
@@ -5196,12 +5191,21 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
PyObject *name = PyList_GET_ITEM(remaining_list, i);
PyObject *type = PyDict_GetItemWithError(field_types, name);
if (!type) {
- if (!PyErr_Occurred()) {
- PyErr_SetObject(PyExc_KeyError, name);
+ if (PyErr_Occurred()) {
+ goto set_remaining_cleanup;
+ }
+ else {
+ if (PyErr_WarnFormat(
+ PyExc_DeprecationWarning, 1,
+ "Field '%U' is missing from %.400s._field_types. "
+ "This will become an error in Python 3.15.",
+ name, Py_TYPE(self)->tp_name
+ ) < 0) {
+ goto set_remaining_cleanup;
+ }
}
- goto set_remaining_cleanup;
}
- if (_PyUnion_Check(type)) {
+ else if (_PyUnion_Check(type)) {
// optional field
// do nothing, we'll have set a None default on the class
}
@@ -5225,8 +5229,7 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
"This will become an error in Python 3.15.",
Py_TYPE(self)->tp_name, name
) < 0) {
- res = -1;
- goto cleanup;
+ goto set_remaining_cleanup;
}
}
}
generated by cgit v0.12 at 2024-11-21 20:46:55 (GMT)