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`ast.class._field_types` causes Exception when `ast.class._fields` does not cause Exception

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Beschreibung

Bug report

Bug description:

_field and _field_types behave differently

Accessing the _field_types attribute of an ast.AST subclass will cause an exception if the class has no _fields, but accessing the _fields attribute never causes an exception.

Example: ast.mod

(.venv) C:\clones\cpython>py
Python 3.13.5 (tags/v3.13.5:6cb20a2, Jun 11 2025, 16:15:46) [MSC v.1943 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import ast
>>> ast.mod._fields
()
>>> ast.mod._field_types
Traceback (most recent call last):
  File "<python-input-2>", line 1, in <module>
    ast.mod._field_types
AttributeError: type object 'mod' has no attribute '_field_types'
>>> 

_field and _field_types for all ast.AST subclasses

Details

(.venv) C:\clones\cpython>C:\clones\cpython\.venv\Scripts\python.exe c:/clones/cpython/field_types.py
3.13.5 (tags/v3.13.5:6cb20a2, Jun 11 2025, 16:15:46) [MSC v.1943 64 bit (AMD64)]

astClass._fields
AST ()
mod ()
stmt ()
expr ()
expr_context ()
boolop ()
operator ()
unaryop ()
cmpop ()
comprehension ('target', 'iter', 'ifs', 'is_async')
excepthandler ()
arguments ('posonlyargs', 'args', 'vararg', 'kwonlyargs', 'kw_defaults', 'kwarg', 'defaults')
arg ('arg', 'annotation', 'type_comment')
keyword ('arg', 'value')
alias ('name', 'asname')
withitem ('context_expr', 'optional_vars')
match_case ('pattern', 'guard', 'body')
pattern ()
type_ignore ()
type_param ()
slice ()
Num ('n',)
Str ('s',)
Bytes ('s',)
NameConstant ('value', 'kind')
Ellipsis ()
Module ('body', 'type_ignores')
Interactive ('body',)
Expression ('body',)
FunctionType ('argtypes', 'returns')
Suite ()
FunctionDef ('name', 'args', 'body', 'decorator_list', 'returns', 'type_comment', 'type_params')
AsyncFunctionDef ('name', 'args', 'body', 'decorator_list', 'returns', 'type_comment', 'type_params')
ClassDef ('name', 'bases', 'keywords', 'body', 'decorator_list', 'type_params')
Return ('value',)
Delete ('targets',)
Assign ('targets', 'value', 'type_comment')
TypeAlias ('name', 'type_params', 'value')
AugAssign ('target', 'op', 'value')
AnnAssign ('target', 'annotation', 'value', 'simple')
For ('target', 'iter', 'body', 'orelse', 'type_comment')
AsyncFor ('target', 'iter', 'body', 'orelse', 'type_comment')
While ('test', 'body', 'orelse')
If ('test', 'body', 'orelse')
With ('items', 'body', 'type_comment')
AsyncWith ('items', 'body', 'type_comment')
Match ('subject', 'cases')
Raise ('exc', 'cause')
Try ('body', 'handlers', 'orelse', 'finalbody')
TryStar ('body', 'handlers', 'orelse', 'finalbody')
Assert ('test', 'msg')
Import ('names',)
ImportFrom ('module', 'names', 'level')
Global ('names',)
Nonlocal ('names',)
Expr ('value',)
Pass ()
Break ()
Continue ()
BoolOp ('op', 'values')
NamedExpr ('target', 'value')
BinOp ('left', 'op', 'right')
UnaryOp ('op', 'operand')
Lambda ('args', 'body')
IfExp ('test', 'body', 'orelse')
Dict ('keys', 'values')
Set ('elts',)
ListComp ('elt', 'generators')
SetComp ('elt', 'generators')
DictComp ('key', 'value', 'generators')
GeneratorExp ('elt', 'generators')
Await ('value',)
Yield ('value',)
YieldFrom ('value',)
Compare ('left', 'ops', 'comparators')
Call ('func', 'args', 'keywords')
FormattedValue ('value', 'conversion', 'format_spec')
JoinedStr ('values',)
Constant ('value', 'kind')
Attribute ('value', 'attr', 'ctx')
Subscript ('value', 'slice', 'ctx')
Starred ('value', 'ctx')
Name ('id', 'ctx')
List ('elts', 'ctx')
Tuple ('elts', 'ctx')
Slice ('lower', 'upper', 'step')
Load ()
Store ()
Del ()
AugLoad ()
AugStore ()
Param ()
And ()
Or ()
Add ()
Sub ()
Mult ()
MatMult ()
Div ()
Mod ()
Pow ()
LShift ()
RShift ()
BitOr ()
BitXor ()
BitAnd ()
FloorDiv ()
Invert ()
Not ()
UAdd ()
USub ()
Eq ()
NotEq ()
Lt ()
LtE ()
Gt ()
GtE ()
Is ()
IsNot ()
In ()
NotIn ()
ExceptHandler ('type', 'name', 'body')
MatchValue ('value',)
MatchSingleton ('value',)
MatchSequence ('patterns',)
MatchMapping ('keys', 'patterns', 'rest')
MatchClass ('cls', 'patterns', 'kwd_attrs', 'kwd_patterns')
MatchStar ('name',)
MatchAs ('pattern', 'name')
MatchOr ('patterns',)
TypeIgnore ('lineno', 'tag')
TypeVar ('name', 'bound', 'default_value')
ParamSpec ('name', 'default_value')
TypeVarTuple ('name', 'default_value')
Index ()
ExtSlice ()
countExceptions = 0

astClass._field_types
AttributeError: AST
AttributeError: mod
AttributeError: stmt
AttributeError: expr
AttributeError: expr_context
AttributeError: boolop
AttributeError: operator
AttributeError: unaryop
AttributeError: cmpop
comprehension {'target': <class 'ast.expr'>, 'iter': <class 'ast.expr'>, 'ifs': list[ast.expr], 'is_async': <class 'int'>}
AttributeError: excepthandler
arguments {'posonlyargs': list[ast.arg], 'args': list[ast.arg], 'vararg': ast.arg | None, 'kwonlyargs': list[ast.arg], 'kw_defaults': list[ast.expr], 'kwarg': ast.arg | None, 'defaults': list[ast.expr]}
arg {'arg': <class 'str'>, 'annotation': ast.expr | None, 'type_comment': str | None}
keyword {'arg': str | None, 'value': <class 'ast.expr'>}
alias {'name': <class 'str'>, 'asname': str | None}
withitem {'context_expr': <class 'ast.expr'>, 'optional_vars': ast.expr | None}
match_case {'pattern': <class 'ast.pattern'>, 'guard': ast.expr | None, 'body': list[ast.stmt]}
AttributeError: pattern
AttributeError: type_ignore
AttributeError: type_param
AttributeError: slice
Num {'value': <class 'object'>, 'kind': str | None}
Str {'value': <class 'object'>, 'kind': str | None}
Bytes {'value': <class 'object'>, 'kind': str | None}
NameConstant {'value': <class 'object'>, 'kind': str | None}
Ellipsis {'value': <class 'object'>, 'kind': str | None}
Module {'body': list[ast.stmt], 'type_ignores': list[ast.type_ignore]}
Interactive {'body': list[ast.stmt]}
Expression {'body': <class 'ast.expr'>}
FunctionType {'argtypes': list[ast.expr], 'returns': <class 'ast.expr'>}
AttributeError: Suite
FunctionDef {'name': <class 'str'>, 'args': <class 'ast.arguments'>, 'body': list[ast.stmt], 'decorator_list': list[ast.expr], 'returns': ast.expr | None, 'type_comment': str | None, 'type_params': list[ast.type_param]}
AsyncFunctionDef {'name': <class 'str'>, 'args': <class 'ast.arguments'>, 'body': list[ast.stmt], 'decorator_list': list[ast.expr], 'returns': ast.expr | None, 'type_comment': str | None, 'type_params': list[ast.type_param]}
ClassDef {'name': <class 'str'>, 'bases': list[ast.expr], 'keywords': list[ast.keyword], 'body': list[ast.stmt], 'decorator_list': list[ast.expr], 'type_params': list[ast.type_param]}
Return {'value': ast.expr | None}
Delete {'targets': list[ast.expr]}
Assign {'targets': list[ast.expr], 'value': <class 'ast.expr'>, 'type_comment': str | None}
TypeAlias {'name': <class 'ast.expr'>, 'type_params': list[ast.type_param], 'value': <class 'ast.expr'>}
AugAssign {'target': <class 'ast.expr'>, 'op': <class 'ast.operator'>, 'value': <class 'ast.expr'>}
AnnAssign {'target': <class 'ast.expr'>, 'annotation': <class 'ast.expr'>, 'value': ast.expr | None, 'simple': <class 'int'>}
For {'target': <class 'ast.expr'>, 'iter': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt], 'type_comment': str | None}
AsyncFor {'target': <class 'ast.expr'>, 'iter': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt], 'type_comment': str | None}
While {'test': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt]}
If {'test': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt]}
With {'items': list[ast.withitem], 'body': list[ast.stmt], 'type_comment': str | None}
AsyncWith {'items': list[ast.withitem], 'body': list[ast.stmt], 'type_comment': str | None}
Match {'subject': <class 'ast.expr'>, 'cases': list[ast.match_case]}
Raise {'exc': ast.expr | None, 'cause': ast.expr | None}
Try {'body': list[ast.stmt], 'handlers': list[ast.excepthandler], 'orelse': list[ast.stmt], 'finalbody': list[ast.stmt]}
TryStar {'body': list[ast.stmt], 'handlers': list[ast.excepthandler], 'orelse': list[ast.stmt], 'finalbody': list[ast.stmt]}
Assert {'test': <class 'ast.expr'>, 'msg': ast.expr | None}
Import {'names': list[ast.alias]}
ImportFrom {'module': str | None, 'names': list[ast.alias], 'level': int | None}
Global {'names': list[str]}
Nonlocal {'names': list[str]}
Expr {'value': <class 'ast.expr'>}
Pass {}
Break {}
Continue {}
BoolOp {'op': <class 'ast.boolop'>, 'values': list[ast.expr]}
NamedExpr {'target': <class 'ast.expr'>, 'value': <class 'ast.expr'>}
BinOp {'left': <class 'ast.expr'>, 'op': <class 'ast.operator'>, 'right': <class 'ast.expr'>}
UnaryOp {'op': <class 'ast.unaryop'>, 'operand': <class 'ast.expr'>}
Lambda {'args': <class 'ast.arguments'>, 'body': <class 'ast.expr'>}
IfExp {'test': <class 'ast.expr'>, 'body': <class 'ast.expr'>, 'orelse': <class 'ast.expr'>}
Dict {'keys': list[ast.expr], 'values': list[ast.expr]}
Set {'elts': list[ast.expr]}
ListComp {'elt': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
SetComp {'elt': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
DictComp {'key': <class 'ast.expr'>, 'value': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
GeneratorExp {'elt': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
Await {'value': <class 'ast.expr'>}
Yield {'value': ast.expr | None}
YieldFrom {'value': <class 'ast.expr'>}
Compare {'left': <class 'ast.expr'>, 'ops': list[ast.cmpop], 'comparators': list[ast.expr]}
Call {'func': <class 'ast.expr'>, 'args': list[ast.expr], 'keywords': list[ast.keyword]}
FormattedValue {'value': <class 'ast.expr'>, 'conversion': <class 'int'>, 'format_spec': ast.expr | None}
JoinedStr {'values': list[ast.expr]}
Constant {'value': <class 'object'>, 'kind': str | None}
Attribute {'value': <class 'ast.expr'>, 'attr': <class 'str'>, 'ctx': <class 'ast.expr_context'>}
Subscript {'value': <class 'ast.expr'>, 'slice': <class 'ast.expr'>, 'ctx': <class 'ast.expr_context'>}
Starred {'value': <class 'ast.expr'>, 'ctx': <class 'ast.expr_context'>}
Name {'id': <class 'str'>, 'ctx': <class 'ast.expr_context'>}
List {'elts': list[ast.expr], 'ctx': <class 'ast.expr_context'>}
Tuple {'elts': list[ast.expr], 'ctx': <class 'ast.expr_context'>}
Slice {'lower': ast.expr | None, 'upper': ast.expr | None, 'step': ast.expr | None}
Load {}
Store {}
Del {}
AttributeError: AugLoad
AttributeError: AugStore
AttributeError: Param
And {}
Or {}
Add {}
Sub {}
Mult {}
MatMult {}
Div {}
Mod {}
Pow {}
LShift {}
RShift {}
BitOr {}
BitXor {}
BitAnd {}
FloorDiv {}
Invert {}
Not {}
UAdd {}
USub {}
Eq {}
NotEq {}
Lt {}
LtE {}
Gt {}
GtE {}
Is {}
IsNot {}
In {}
NotIn {}
ExceptHandler {'type': ast.expr | None, 'name': str | None, 'body': list[ast.stmt]}
MatchValue {'value': <class 'ast.expr'>}
MatchSingleton {'value': <class 'object'>}
MatchSequence {'patterns': list[ast.pattern]}
MatchMapping {'keys': list[ast.expr], 'patterns': list[ast.pattern], 'rest': str | None}
MatchClass {'cls': <class 'ast.expr'>, 'patterns': list[ast.pattern], 'kwd_attrs': list[str], 'kwd_patterns': list[ast.pattern]}
MatchStar {'name': str | None}
MatchAs {'pattern': ast.pattern | None, 'name': str | None}
MatchOr {'patterns': list[ast.pattern]}
TypeIgnore {'lineno': <class 'int'>, 'tag': <class 'str'>}
TypeVar {'name': <class 'str'>, 'bound': ast.expr | None, 'default_value': ast.expr | None}
ParamSpec {'name': <class 'str'>, 'default_value': ast.expr | None}
TypeVarTuple {'name': <class 'str'>, 'default_value': ast.expr | None}
AttributeError: Index
AttributeError: ExtSlice
countExceptions = 20

No errors after code changes

After adding logic to "Parser/asdl_c.py" to treat _field_types similar to _fields, the exceptions were replaced with empty dictionaries.

Summary

(.venv) C:\clones\cpython>C:\clones\cpython\python c:/clones/cpython/field_types.py
Running Debug|x64 interpreter...
3.15.0a0 (heads/main-dirty:b14986c9146, Jun 21 2025, 15:02:00) [MSC v.1944 64 bit (AMD64)]

astClass._fields
countExceptions = 0

astClass._field_types
countExceptions = 0

_field_types for all ast.AST subclasses

Details

AST {}
mod {}
stmt {}
expr {}
expr_context {}
boolop {}
operator {}
unaryop {}
cmpop {}
comprehension {'target': <class 'ast.expr'>, 'iter': <class 'ast.expr'>, 'ifs': list[ast.expr], 'is_async': <class 'int'>}
excepthandler {}
arguments {'posonlyargs': list[ast.arg], 'args': list[ast.arg], 'vararg': ast.arg | None, 'kwonlyargs': list[ast.arg], 'kw_defaults': list[ast.expr], 'kwarg': ast.arg | None, 'defaults': list[ast.expr]}
arg {'arg': <class 'str'>, 'annotation': ast.expr | None, 'type_comment': str | None}
keyword {'arg': str | None, 'value': <class 'ast.expr'>}
alias {'name': <class 'str'>, 'asname': str | None}
withitem {'context_expr': <class 'ast.expr'>, 'optional_vars': ast.expr | None}
match_case {'pattern': <class 'ast.pattern'>, 'guard': ast.expr | None, 'body': list[ast.stmt]}
pattern {}
type_ignore {}
type_param {}
slice {}
Module {'body': list[ast.stmt], 'type_ignores': list[ast.type_ignore]}
Interactive {'body': list[ast.stmt]}
Expression {'body': <class 'ast.expr'>}
FunctionType {'argtypes': list[ast.expr], 'returns': <class 'ast.expr'>}
Suite {}
FunctionDef {'name': <class 'str'>, 'args': <class 'ast.arguments'>, 'body': list[ast.stmt], 'decorator_list': list[ast.expr], 'returns': ast.expr | None, 'type_comment': str | None, 'type_params': list[ast.type_param]}
AsyncFunctionDef {'name': <class 'str'>, 'args': <class 'ast.arguments'>, 'body': list[ast.stmt], 'decorator_list': list[ast.expr], 'returns': ast.expr | None, 'type_comment': str | None, 'type_params': list[ast.type_param]}
ClassDef {'name': <class 'str'>, 'bases': list[ast.expr], 'keywords': list[ast.keyword], 'body': list[ast.stmt], 'decorator_list': list[ast.expr], 'type_params': list[ast.type_param]}
Return {'value': ast.expr | None}
Delete {'targets': list[ast.expr]}
Assign {'targets': list[ast.expr], 'value': <class 'ast.expr'>, 'type_comment': str | None}
TypeAlias {'name': <class 'ast.expr'>, 'type_params': list[ast.type_param], 'value': <class 'ast.expr'>}
AugAssign {'target': <class 'ast.expr'>, 'op': <class 'ast.operator'>, 'value': <class 'ast.expr'>}
AnnAssign {'target': <class 'ast.expr'>, 'annotation': <class 'ast.expr'>, 'value': ast.expr | None, 'simple': <class 'int'>}
For {'target': <class 'ast.expr'>, 'iter': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt], 'type_comment': str | None}
AsyncFor {'target': <class 'ast.expr'>, 'iter': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt], 'type_comment': str | None}
While {'test': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt]}
If {'test': <class 'ast.expr'>, 'body': list[ast.stmt], 'orelse': list[ast.stmt]}
With {'items': list[ast.withitem], 'body': list[ast.stmt], 'type_comment': str | None}
AsyncWith {'items': list[ast.withitem], 'body': list[ast.stmt], 'type_comment': str | None}
Match {'subject': <class 'ast.expr'>, 'cases': list[ast.match_case]}
Raise {'exc': ast.expr | None, 'cause': ast.expr | None}
Try {'body': list[ast.stmt], 'handlers': list[ast.excepthandler], 'orelse': list[ast.stmt], 'finalbody': list[ast.stmt]}
TryStar {'body': list[ast.stmt], 'handlers': list[ast.excepthandler], 'orelse': list[ast.stmt], 'finalbody': list[ast.stmt]}
Assert {'test': <class 'ast.expr'>, 'msg': ast.expr | None}
Import {'names': list[ast.alias]}
ImportFrom {'module': str | None, 'names': list[ast.alias], 'level': int | None}
Global {'names': list[str]}
Nonlocal {'names': list[str]}
Expr {'value': <class 'ast.expr'>}
Pass {}
Break {}
Continue {}
BoolOp {'op': <class 'ast.boolop'>, 'values': list[ast.expr]}
NamedExpr {'target': <class 'ast.expr'>, 'value': <class 'ast.expr'>}
BinOp {'left': <class 'ast.expr'>, 'op': <class 'ast.operator'>, 'right': <class 'ast.expr'>}
UnaryOp {'op': <class 'ast.unaryop'>, 'operand': <class 'ast.expr'>}
Lambda {'args': <class 'ast.arguments'>, 'body': <class 'ast.expr'>}
IfExp {'test': <class 'ast.expr'>, 'body': <class 'ast.expr'>, 'orelse': <class 'ast.expr'>}
Dict {'keys': list[ast.expr], 'values': list[ast.expr]}
Set {'elts': list[ast.expr]}
ListComp {'elt': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
SetComp {'elt': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
DictComp {'key': <class 'ast.expr'>, 'value': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
GeneratorExp {'elt': <class 'ast.expr'>, 'generators': list[ast.comprehension]}
Await {'value': <class 'ast.expr'>}
Yield {'value': ast.expr | None}
YieldFrom {'value': <class 'ast.expr'>}
Compare {'left': <class 'ast.expr'>, 'ops': list[ast.cmpop], 'comparators': list[ast.expr]}
Call {'func': <class 'ast.expr'>, 'args': list[ast.expr], 'keywords': list[ast.keyword]}
FormattedValue {'value': <class 'ast.expr'>, 'conversion': <class 'int'>, 'format_spec': ast.expr | None}
Interpolation {'value': <class 'ast.expr'>, 'str': <class 'object'>, 'conversion': <class 'int'>, 'format_spec': ast.expr | None}
JoinedStr {'values': list[ast.expr]}
TemplateStr {'values': list[ast.expr]}
Constant {'value': <class 'object'>, 'kind': str | None}
Attribute {'value': <class 'ast.expr'>, 'attr': <class 'str'>, 'ctx': <class 'ast.expr_context'>}
Subscript {'value': <class 'ast.expr'>, 'slice': <class 'ast.expr'>, 'ctx': <class 'ast.expr_context'>}
Starred {'value': <class 'ast.expr'>, 'ctx': <class 'ast.expr_context'>}
Name {'id': <class 'str'>, 'ctx': <class 'ast.expr_context'>}
List {'elts': list[ast.expr], 'ctx': <class 'ast.expr_context'>}
Tuple {'elts': list[ast.expr], 'ctx': <class 'ast.expr_context'>}
Slice {'lower': ast.expr | None, 'upper': ast.expr | None, 'step': ast.expr | None}
Load {}
Store {}
Del {}
AugLoad {}
AugStore {}
Param {}
And {}
Or {}
Add {}
Sub {}
Mult {}
MatMult {}
Div {}
Mod {}
Pow {}
LShift {}
RShift {}
BitOr {}
BitXor {}
BitAnd {}
FloorDiv {}
Invert {}
Not {}
UAdd {}
USub {}
Eq {}
NotEq {}
Lt {}
LtE {}
Gt {}
GtE {}
Is {}
IsNot {}
In {}
NotIn {}
ExceptHandler {'type': ast.expr | None, 'name': str | None, 'body': list[ast.stmt]}
MatchValue {'value': <class 'ast.expr'>}
MatchSingleton {'value': <class 'object'>}
MatchSequence {'patterns': list[ast.pattern]}
MatchMapping {'keys': list[ast.expr], 'patterns': list[ast.pattern], 'rest': str | None}
MatchClass {'cls': <class 'ast.expr'>, 'patterns': list[ast.pattern], 'kwd_attrs': list[str], 'kwd_patterns': list[ast.pattern]}
MatchStar {'name': str | None}
MatchAs {'pattern': ast.pattern | None, 'name': str | None}
MatchOr {'patterns': list[ast.pattern]}
TypeIgnore {'lineno': <class 'int'>, 'tag': <class 'str'>}
TypeVar {'name': <class 'str'>, 'bound': ast.expr | None, 'default_value': ast.expr | None}
ParamSpec {'name': <class 'str'>, 'default_value': ast.expr | None}
TypeVarTuple {'name': <class 'str'>, 'default_value': ast.expr | None}
Index {}
ExtSlice {}
countExceptions = 0

Check for errors on branches

Not applicable to 3.9, 3.10, 3.11, 3.12.

Branch 3.13

Details

(.venv) C:\clones\cpython>C:\clones\cpython\python c:/clones/cpython/field_types.py
Running Debug|x64 interpreter...
3.13.5+ (heads/3.13:4eab9da960d, Jun 21 2025, 14:44:53) [MSC v.1944 64 bit (AMD64)]

astClass._fields
countExceptions = 0

astClass._field_types
AttributeError: AST
AttributeError: mod
AttributeError: stmt
AttributeError: expr
AttributeError: expr_context
AttributeError: boolop
AttributeError: operator
AttributeError: unaryop
AttributeError: cmpop
AttributeError: excepthandler
AttributeError: pattern
AttributeError: type_ignore
AttributeError: type_param
AttributeError: slice
AttributeError: Suite
AttributeError: AugLoad
AttributeError: AugStore
AttributeError: Param
AttributeError: Index
AttributeError: ExtSlice
countExceptions = 20

Branch 3.14

Details

(.venv) C:\clones\cpython>C:\clones\cpython\python c:/clones/cpython/field_types.py
Running Debug|x64 interpreter...
3.14.0b3+ (heads/3.14:73e2089ed13, Jun 21 2025, 14:57:19) [MSC v.1944 64 bit (AMD64)]

astClass._fields
countExceptions = 0

astClass._field_types
AttributeError: AST
AttributeError: mod
AttributeError: stmt
AttributeError: expr
AttributeError: expr_context
AttributeError: boolop
AttributeError: operator
AttributeError: unaryop
AttributeError: cmpop
AttributeError: excepthandler
AttributeError: pattern
AttributeError: type_ignore
AttributeError: type_param
AttributeError: slice
AttributeError: Suite
AttributeError: AugLoad
AttributeError: AugStore
AttributeError: Param
AttributeError: Index
AttributeError: ExtSlice
countExceptions = 20

Branch main

Details

(.venv) C:\clones\cpython>C:\clones\cpython\python c:/clones/cpython/field_types.py
Running Debug|x64 interpreter...
3.15.0a0 (heads/main:b14986c9146, Jun 21 2025, 14:59:45) [MSC v.1944 64 bit (AMD64)]

astClass._fields
countExceptions = 0

astClass._field_types
AttributeError: AST
AttributeError: mod
AttributeError: stmt
AttributeError: expr
AttributeError: expr_context
AttributeError: boolop
AttributeError: operator
AttributeError: unaryop
AttributeError: cmpop
AttributeError: excepthandler
AttributeError: pattern
AttributeError: type_ignore
AttributeError: type_param
AttributeError: slice
AttributeError: Suite
AttributeError: AugLoad
AttributeError: AugStore
AttributeError: Param
AttributeError: Index
AttributeError: ExtSlice
countExceptions = 20

Python code used to generate the above tests

Details

from itertools import chain
import ast
import sys

print(sys.version, end='\n\n')

countExceptions = 0
print('astClass._fields')
for astClass in [C for C in [ast.AST,*chain(*(c.__subclasses__() for c in [ast.AST,ast.Constant,*ast.AST.__subclasses__()]))] if issubclass(C,ast.AST)]:
	try:
		print(astClass.__name__, astClass._fields)
		# astClass._fields
	except AttributeError as ERRORmessage:
		print(ERRORmessage.__class__.__name__, astClass.__name__, sep=': ')
		countExceptions += 1
print(f"{countExceptions = }\n")

countExceptions = 0
print('astClass._field_types')
for astClass in [C for C in [ast.AST,*chain(*(c.__subclasses__() for c in [ast.AST,ast.Constant,*ast.AST.__subclasses__()]))] if issubclass(C,ast.AST)]:
	try:
		print(astClass.__name__, astClass._field_types)
		# astClass._field_types
	except AttributeError as ERRORmessage:
		print(ERRORmessage.__class__.__name__, astClass.__name__, sep=': ')
		countExceptions += 1
print(f"{countExceptions = }")

CPython versions tested on:

3.13, 3.14, CPython main branch

Operating systems tested on:

Windows

Linked PRs
  • gh-135800

Beitragsleitfaden

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Erste Schritte

  1. Lies das ganze Issue und danach den Beitragsleitfaden des Projekts.
  2. Schreib ins Issue, dass du es übernimmst — das erspart doppelte Arbeit.
  3. Forke das Repository und arbeite in einem Branch.
  4. Öffne einen Pull Request, der die Issue-Nummer nennt.

Rechercherichtung

Beginnen Sie mit Parser/asdl_c.py, wo der Issue das Hinzufügen von Logik beschreibt, durch die _field_types wie _fields behandelt wird. Führen Sie das erwähnte field_types.py-Skript mit dem betroffenen Interpreter aus und vergleichen Sie AST-Unterklassen mit und ohne Felder. Die Aufgabe ist erledigt, wenn die gemeldeten AttributeError-Fälle durch leere Dictionaries ersetzt werden und die Skriptausgabe keine Fehler enthält.

Vom Indexierungsmodell aus dem Issue-Text verfasst.

Bewertung

Tech-Stack
python
Bereich
compilers
Issue-Typ
Bug
Schwierigkeit
3/5
Geschätzter Aufwand
1-2 Tage
Aktivitätsstatus
Veraltet
Klarheit
Größtenteils klar
Anfängerfreundlichkeit
35/100

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