improvement: Add AST subclass constructors by bzoracler · Pull Request #11880 · python/typeshed · GitHub

Fixes #8378

ast.AST no longer owns attributes which may not exist on all subclasses (node locations, type_comment). These are all shifted to subclasses which actually own the attributes (d5e0838, 75a2e8e, f9a2cb9)
ast.AST no longer has the constructor __init__(self, *args: Any, **kwargs: Any).
All subclasses of ast.AST which have a non-empty _fields: ClassVar[tuple[str, ...]] or _attributes: ClassVar[tuple[str, ...]] now have their own __init__ constructor (d886a45). The constructor has:
- Positional-or-keyword arguments in the order in which they appear in _fields, and
- Non-mandatory keyword-only arguments from _attributes. These are expressed using a combination of typing.TypedDict and typing_extensions.Unpack.
  - These are non-mandatory because I expect most users won't pass explicit locations, but rather use something like ast.fix_missing_locations.

Updates:

Arguments of type ast.expr_context are not required to be passed to the constructor, but they will not exist on node instances for Python < 3.13.
Arguments of type list are not required to be passed to the constructor for Python >= 3.13.

improvement: shift `type_comment` attribute to classes which contain it

Thanks for this, I had been thinking of adding it but hadn't gotten around to it.

These list fields should default to the empty list on 3.13+.

Addressed in c82a5fa

I don't think type_comment needs to be keyword-only on this overload.

Addressed in 9655775

…o constructor

I didn't add these other changes from Python 3.13 runtime to this PR:

AST._field_types - not sure what the intention is for the values of these dictionaries; are they meant to be for runtime introspection, or can they be anything?
The default_value parameter for ast.TypeVar, ast.ParamSpec, ast.TypeVarTuple - the runtime suggests that this defaults to None if not passed, but the grammar does not mark this field as optional. (I misread the grammar, they're definitely optional)

AST._field_types - not sure what the intention is for the values of these dictionaries; are they meant to be for runtime introspection, or can they be anything?

It's used by the constructor of AST nodes to figure out what defaults to use. I did document it, so I think we should add it to the ast.AST class as ClassVar[dict[str, Any]].

Diff from mypy_primer, showing the effect of this PR on open source code:

pyp (https://github.com/hauntsaninja/pyp)
+ pyp.py:585: error: "AST" has no attribute "lineno"  [attr-defined]
+ pyp.py:586: error: "AST" has no attribute "end_lineno"  [attr-defined]

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/ext/autodoc/preserve_defaults.py: note: In function "get_default_value":
+ sphinx/ext/autodoc/preserve_defaults.py:114:12: error: "AST" has no attribute "lineno"  [attr-defined]
+ sphinx/ext/autodoc/preserve_defaults.py:114:31: error: "AST" has no attribute "end_lineno"  [attr-defined]
+ sphinx/ext/autodoc/preserve_defaults.py:115:26: error: "AST" has no attribute "lineno"  [attr-defined]
+ sphinx/ext/autodoc/preserve_defaults.py:116:25: error: "AST" has no attribute "col_offset"  [attr-defined]
+ sphinx/ext/autodoc/preserve_defaults.py:116:45: error: "AST" has no attribute "end_col_offset"  [attr-defined]

mypy (https://github.com/python/mypy)
+ mypy/fastparse.py:1998: error: "Index" has no attribute "col_offset"  [attr-defined]
+ mypy/fastparse.py:2001: error: "Slice" has no attribute "col_offset"  [attr-defined]
+ mypy/fastparse.py:2002: error: Argument 1 to "Tuple" has incompatible type "List[slice]"; expected "List[expr]"  [arg-type]

pytest (https://github.com/pytest-dev/pytest)
+ src/_pytest/assertion/rewrite.py:839: error: Argument 1 to "Dict" has incompatible type "list[Constant]"; expected "list[expr | None]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:839: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:839: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:932: error: Argument 3 to "If" has incompatible type "list[If]"; expected "list[stmt]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:932: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:932: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:938: error: Argument 1 to "Assign" has incompatible type "list[Name]"; expected "list[expr]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:938: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:938: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:963: error: Argument 1 to "Assign" has incompatible type "list[Name]"; expected "list[expr]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:963: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:963: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:1145: error: Argument 1 to "Tuple" has incompatible type "list[Constant]"; expected "list[expr]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:1145: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:1145: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:1146: error: Argument 1 to "Tuple" has incompatible type "list[Name]"; expected "list[expr]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:1146: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:1146: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:1147: error: Argument 1 to "Tuple" has incompatible type "list[Constant]"; expected "list[expr]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:1147: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:1147: note: Consider using "Sequence" instead, which is covariant
+ src/_pytest/assertion/rewrite.py:1151: error: Argument 2 to "BoolOp" has incompatible type "list[Name]"; expected "list[expr]"  [arg-type]
+ src/_pytest/assertion/rewrite.py:1151: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ src/_pytest/assertion/rewrite.py:1151: note: Consider using "Sequence" instead, which is covariant
+ testing/test_assertrewrite.py:133: error: "AST" has no attribute "lineno"  [attr-defined]
+ testing/test_assertrewrite.py:134: error: "AST" has no attribute "col_offset"  [attr-defined]
+ testing/test_assertrewrite.py:135: error: "AST" has no attribute "end_lineno"  [attr-defined]
+ testing/test_assertrewrite.py:136: error: "AST" has no attribute "end_col_offset"  [attr-defined]

werkzeug (https://github.com/pallets/werkzeug)
+ src/werkzeug/routing/rules.py:785: error: Argument 1 to "JoinedStr" has incompatible type "list[AST]"; expected "list[expr]"  [arg-type]
+ src/werkzeug/routing/rules.py:788: error: List item 0 has incompatible type "AST"; expected "expr"  [list-item]
+ src/werkzeug/routing/rules.py:788: error: List item 1 has incompatible type "AST"; expected "expr"  [list-item]
+ src/werkzeug/routing/rules.py:818: error: "AST" has no attribute "lineno"  [attr-defined]
+ src/werkzeug/routing/rules.py:820: error: "AST" has no attribute "end_lineno"  [attr-defined]
+ src/werkzeug/routing/rules.py:820: error: "AST" has no attribute "lineno"  [attr-defined]
+ src/werkzeug/routing/rules.py:822: error: "AST" has no attribute "col_offset"  [attr-defined]
+ src/werkzeug/routing/rules.py:824: error: "AST" has no attribute "end_col_offset"  [attr-defined]
+ src/werkzeug/routing/rules.py:824: error: "AST" has no attribute "col_offset"  [attr-defined]

ibis (https://github.com/ibis-project/ibis)
+ ibis/backends/bigquery/udf/core.py:66: error: Missing positional arguments "args", "keywords" in call to "Call"  [call-arg]
+ ibis/backends/bigquery/udf/core.py:79: error: Missing positional arguments "args", "keywords" in call to "Call"  [call-arg]
+ ibis/backends/bigquery/udf/core.py:85: error: Missing positional arguments "args", "keywords" in call to "Call"  [call-arg]
+ ibis/backends/bigquery/udf/core.py:85: error: Missing positional argument "value" in call to "Attribute"  [call-arg]
+ ibis/backends/bigquery/udf/core.py:95: error: Missing positional arguments "args", "keywords" in call to "Call"  [call-arg]

flake8-pyi (https://github.com/PyCQA/flake8-pyi)
+ pyi.py:2249: error: "AST" has no attribute "lineno"  [attr-defined]
+ pyi.py:2249: error: "AST" has no attribute "col_offset"  [attr-defined]

streamlit (https://github.com/streamlit/streamlit)
+ lib/streamlit/runtime/scriptrunner/magic.py: note: In function "_build_st_write_call":
+ lib/streamlit/runtime/scriptrunner/magic.py:166:12: error: Unexpected keyword argument "kwargs" for "Call"; did you mean "args"?  [call-arg]
+ note: "Call" defined here
+ lib/streamlit/runtime/scriptrunner/magic.py:166:12: error: Unexpected keyword argument "starargs" for "Call"  [call-arg]
+ note: "Call" defined here

Thank you!

python/typeshed#11880 correctly points out that not all AST nodes have a line and column number.

python/typeshed#11880 adds more precise types for AST nodes. I'm submitting some changes to adapt pytest to these changes.

python/typeshed#11880 correctly points out that not all AST nodes have a line and column number.

Adapting to changes in python/typeshed#11880. This mostly adds more precise types for individual pieces of AST.

Followup from python/typeshed#11880. Not all AST nodes have a lineno; in this file only parameter defaults are passed to this function, which are always ast.expr.

python/typeshed#11880 adds more precise types for AST nodes. I'm submitting some changes to adapt pytest to these changes.

See https://docs.python.org/3.10/library/ast.html#abstract-grammar for a reference on the attributes `ast.Call` takes. A future version of mypy will give a type error for this code (python/typeshed#11880).

See https://docs.python.org/3.10/library/ast.html#abstract-grammar for a reference on the attributes `ast.Call` takes. A future version of mypy will give a type error for this code (python/typeshed#11880). Co-authored-by: Vincent Donato <vincent@streamlit.io>

Adapting to changes in python/typeshed#11880. This mostly adds more precise types for individual pieces of AST.

See https://docs.python.org/3.10/library/ast.html#abstract-grammar for a reference on the attributes `ast.Call` takes. A future version of mypy will give a type error for this code (python/typeshed#11880). Co-authored-by: Vincent Donato <vincent@streamlit.io>

bzoracler added 5 commits May 9, 2024 23:56

improvement: shift node location attributes to classes which have them

d5e0838

Update _ast.pyi

75a2e8e

improvement: shift `type_comment` attribute to classes which contain it

improvement: add missing node field

f9a2cb9

improvement: add precise AST subclass constructors

d886a45

test: update allowlist

25d4dad

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bzoracler added 2 commits May 10, 2024 00:33

fix: delegate version-specific nodes to separate allowlists

70fdb52

fix: typo in parameter

c88c4aa

AlexWaygood reviewed May 9, 2024

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style: Shorten signatures

1135b28

AlexWaygood mentioned this pull request May 9, 2024

Allow using typing_extensions.TypeVar in stubs PyCQA/flake8-pyi#486

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JelleZijlstra mentioned this pull request May 9, 2024

Default expr_context parameters in ast to Load() python/cpython#118851

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JelleZijlstra reviewed May 9, 2024

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bzoracler and others added 5 commits May 10, 2024 17:34

fix: remove unnecessary keyword-only constraint

9655775

improvement: don't require args of type expr_context to be passed t…

bb880f2

…o constructor

feat: empty list defaults in Python 3.13

c82a5fa

style: keep _SliceAttributes together with usage location

aea4c01

[pre-commit.ci] auto fixes from pre-commit.com hooks

1e489b1

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fix: add missing default_value field for Python 3.13

b82fc4e

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improvement: add new Python 3.13 class variable

cc50db4

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fix: wrong attribute conditional location

cc2cd65

JelleZijlstra approved these changes May 18, 2024

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JelleZijlstra merged commit 5bd7150 into python:main May 18, 2024

JelleZijlstra added a commit to PyCQA/flake8-pyi that referenced this pull request May 18, 2024

Fix new type error

a0370f1

python/typeshed#11880 correctly points out that not all AST nodes have a line and column number.

JelleZijlstra mentioned this pull request May 18, 2024

Fix new type error PyCQA/flake8-pyi#489

Merged

JelleZijlstra added a commit to JelleZijlstra/pytest that referenced this pull request May 18, 2024

Fix new typing issues in AST code

8bb493b

python/typeshed#11880 adds more precise types for AST nodes. I'm submitting some changes to adapt pytest to these changes.

JelleZijlstra mentioned this pull request May 18, 2024

Fix new typing issues in AST code pytest-dev/pytest#12337

Merged

AlexWaygood pushed a commit to PyCQA/flake8-pyi that referenced this pull request May 18, 2024

Fix new type error (#489 )

f1230fc

python/typeshed#11880 correctly points out that not all AST nodes have a line and column number.

JelleZijlstra added a commit to JelleZijlstra/werkzeug that referenced this pull request May 18, 2024

Improve types for AST handling

8a672ef

Adapting to changes in python/typeshed#11880. This mostly adds more precise types for individual pieces of AST.

JelleZijlstra mentioned this pull request May 18, 2024

Improve types for AST handling pallets/werkzeug#2905

Merged

JelleZijlstra mentioned this pull request May 18, 2024

More precise types in preserve_defaults.py sphinx-doc/sphinx#12385

Merged

bluetech pushed a commit to pytest-dev/pytest that referenced this pull request May 18, 2024

Fix new typing issues in AST code (#12337 )

ee9ea70

python/typeshed#11880 adds more precise types for AST nodes. I'm submitting some changes to adapt pytest to these changes.

bzoracler deleted the ast-subclass-constructors branch May 18, 2024 20:12

JelleZijlstra mentioned this pull request May 18, 2024

Remove non-existent kwargs in ast.Call() call streamlit/streamlit#8711

Merged

davidism pushed a commit to JelleZijlstra/werkzeug that referenced this pull request Aug 20, 2024

Improve types for AST handling

2ea2540

Adapting to changes in python/typeshed#11880. This mostly adds more precise types for individual pieces of AST.

Avasam mentioned this pull request Apr 10, 2025

A couple of _ast related issues #4760

Closed

                       __match_args__ = ("body", "type_ignores")
                   body: list[stmt]
                   type_ignores: list[TypeIgnore]
+                  def __init__(self, body: list[stmt], type_ignores: list[TypeIgnore]) -> None: ...

+                          decorator_list: list[expr],
+                          returns: expr | None = None,
+                          *,
+                          type_comment: str | None = None,

improvement: Add AST subclass constructors by bzoracler · Pull Request #11880 · python/typeshed · GitHub

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improvement: Add AST subclass constructors - #11880

improvement: Add AST subclass constructors#11880JelleZijlstra merged 16 commits intopython:mainpython/typeshed:mainfrom bzoracler:ast-subclass-constructorsCopy head branch name to clipboard

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improvement: Add AST subclass constructors#11880
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