PEP 749 support #1450
Description
attrs doesn't currently support PEP 749 annotations.
On Python 3.14, this works:
class A:
b: B
class B:
passIf we try using attrs, it doesn't:
from attrs import define
@define
class A:
b: B
class B:
passTraceback (most recent call last):
File "/Users/tintvrtkovic/pg/attrs/a01.py", line 6, in <module>
@define
^^^^^^
File "/Users/tintvrtkovic/pg/attrs/src/attr/_next_gen.py", line 409, in define
return wrap(maybe_cls)
File "/Users/tintvrtkovic/pg/attrs/src/attr/_next_gen.py", line 400, in wrap
return do_it(cls, True)
File "/Users/tintvrtkovic/pg/attrs/src/attr/_next_gen.py", line 346, in do_it
return attrs(
maybe_cls=cls,
...<20 lines>...
match_args=match_args,
)
File "/Users/tintvrtkovic/pg/attrs/src/attr/_make.py", line 1554, in attrs
return wrap(maybe_cls)
File "/Users/tintvrtkovic/pg/attrs/src/attr/_make.py", line 1452, in wrap
builder = _ClassBuilder(
cls,
...<18 lines>...
field_transformer,
)
File "/Users/tintvrtkovic/pg/attrs/src/attr/_make.py", line 679, in __init__
attrs, base_attrs, base_map = _transform_attrs(
~~~~~~~~~~~~~~~~^
cls,
^^^^
...<4 lines>...
field_transformer,
^^^^^^^^^^^^^^^^^^
)
^
File "/Users/tintvrtkovic/pg/attrs/src/attr/_make.py", line 390, in _transform_attrs
anns = _get_annotations(cls)
File "/Users/tintvrtkovic/.local/share/uv/python/cpython-3.14.0b1-macos-aarch64-none/lib/python3.14/annotationlib.py", line 862, in get_annotations
ann = _get_dunder_annotations(obj)
File "/Users/tintvrtkovic/.local/share/uv/python/cpython-3.14.0b1-macos-aarch64-none/lib/python3.14/annotationlib.py", line 1014, in _get_dunder_annotations
ann = getattr(obj, "__annotations__", None)
File "/Users/tintvrtkovic/pg/attrs/a01.py", line 8, in __annotate__
b: B
^
NameError: name 'B' is not defined
This is because we eagerly evaluate annotations; this cannot work with forward references (which is the entire point of the new handling of annotations).
Dataclasses work:
from dataclasses import dataclass
@dataclass
class A:
b: B
class B:
pass