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gh-149415: Replace typing._LazyAnnotationLib with lazy import #149416

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gh-149415: Replace typing._LazyAnnotationLib with lazy import #149416

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gh-149415: Replace `typing._LazyAnnotationLib` with `lazy import`
sobolevn May 5, 2026
765acd2
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sobolevn May 5, 2026
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74 changes: 33 additions & 41 deletions Lib/typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
import sys
import types
from types import GenericAlias
lazy import annotationlib

from _typing import (
_idfunc,
Expand Down Expand Up @@ -163,15 +164,6 @@
'Unpack',
]

class _LazyAnnotationLib:
def __getattr__(self, attr):
global _lazy_annotationlib
import annotationlib
_lazy_annotationlib = annotationlib
return getattr(annotationlib, attr)

_lazy_annotationlib = _LazyAnnotationLib()


def _type_convert(arg, module=None, *, allow_special_forms=False, owner=None):
"""For converting None to type(None), and strings to ForwardRef."""
Expand Down Expand Up @@ -255,7 +247,7 @@ def _type_repr(obj):
if isinstance(obj, tuple):
# Special case for `repr` of types with `ParamSpec`:
return '[' + ', '.join(_type_repr(t) for t in obj) + ']'
return _lazy_annotationlib.type_repr(obj)
return annotationlib.type_repr(obj)


def _collect_type_parameters(
Expand Down Expand Up @@ -463,7 +455,7 @@ def _eval_type(t, globalns, localns, type_params, *, recursive_guard=frozenset()
recursive_guard is used to prevent infinite recursion with a recursive
ForwardRef.
"""
if isinstance(t, _lazy_annotationlib.ForwardRef):
if isinstance(t, annotationlib.ForwardRef):
# If the forward_ref has __forward_module__ set, evaluate() infers the globals
# from the module, and it will probably pick better than the globals we have here.
# We do this only for calls from get_type_hints() (which opts in through the
Expand Down Expand Up @@ -1004,7 +996,7 @@ def _make_forward_ref(code, *, parent_fwdref=None, **kwargs):
kwargs['module'] = parent_fwdref.__forward_module__
if parent_fwdref.__owner__ is not None:
kwargs['owner'] = parent_fwdref.__owner__
forward_ref = _lazy_annotationlib.ForwardRef(code, **kwargs)
forward_ref = annotationlib.ForwardRef(code, **kwargs)
# For compatibility, eagerly compile the forwardref's code.
forward_ref.__forward_code__
return forward_ref
Expand Down Expand Up @@ -1039,18 +1031,18 @@ def evaluate_forward_ref(
VALUE.

"""
if format == _lazy_annotationlib.Format.STRING:
if format == annotationlib.Format.STRING:
return forward_ref.__forward_arg__
if forward_ref.__forward_arg__ in _recursive_guard:
return forward_ref

if format is None:
format = _lazy_annotationlib.Format.VALUE
format = annotationlib.Format.VALUE
value = forward_ref.evaluate(globals=globals, locals=locals,
type_params=type_params, owner=owner, format=format)

if (isinstance(value, _lazy_annotationlib.ForwardRef)
and format == _lazy_annotationlib.Format.FORWARDREF):
if (isinstance(value, annotationlib.ForwardRef)
and format == annotationlib.Format.FORWARDREF):
return value

if isinstance(value, str):
Expand Down Expand Up @@ -1891,8 +1883,8 @@ def _get_protocol_attrs(cls):
annotations = base.__annotations__
except Exception:
# Only go through annotationlib to handle deferred annotations if we need to
annotations = _lazy_annotationlib.get_annotations(
base, format=_lazy_annotationlib.Format.FORWARDREF
annotations = annotationlib.get_annotations(
base, format=annotationlib.Format.FORWARDREF
)
for attr in (*base.__dict__, *annotations):
if not attr.startswith('_abc_') and attr not in EXCLUDED_ATTRIBUTES:
Expand Down Expand Up @@ -2140,8 +2132,8 @@ def _proto_hook(cls, other):
try:
annos = base.__annotations__
except Exception:
annos = _lazy_annotationlib.get_annotations(
base, format=_lazy_annotationlib.Format.FORWARDREF
annos = annotationlib.get_annotations(
base, format=annotationlib.Format.FORWARDREF
)
if attr in annos:
break
Expand Down Expand Up @@ -2428,14 +2420,14 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False,
"""
if getattr(obj, '__no_type_check__', None):
return {}
Format = _lazy_annotationlib.Format
Format = annotationlib.Format
if format is None:
format = Format.VALUE
# Classes require a special treatment.
if isinstance(obj, type):
hints = {}
for base in reversed(obj.__mro__):
ann = _lazy_annotationlib.get_annotations(base, format=format)
ann = annotationlib.get_annotations(base, format=format)
if format == Format.STRING:
hints.update(ann)
continue
Expand Down Expand Up @@ -2468,7 +2460,7 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False,
else:
return {k: _strip_annotations(t) for k, t in hints.items()}

hints = _lazy_annotationlib.get_annotations(obj, format=format)
hints = annotationlib.get_annotations(obj, format=format)
if (
not hints
and not isinstance(obj, types.ModuleType)
Expand Down Expand Up @@ -3020,10 +3012,10 @@ def _make_eager_annotate(types):
for key, val in types.items()}
def annotate(format):
match format:
case _lazy_annotationlib.Format.VALUE | _lazy_annotationlib.Format.FORWARDREF:
case annotationlib.Format.VALUE | annotationlib.Format.FORWARDREF:
return checked_types
case _lazy_annotationlib.Format.STRING:
return _lazy_annotationlib.annotations_to_string(types)
case annotationlib.Format.STRING:
return annotationlib.annotations_to_string(types)
case _:
raise NotImplementedError(format)
return annotate
Expand Down Expand Up @@ -3053,19 +3045,19 @@ def __new__(cls, typename, bases, ns):
types = ns["__annotations__"]
field_names = list(types)
annotate = _make_eager_annotate(types)
elif (original_annotate := _lazy_annotationlib.get_annotate_from_class_namespace(ns)) is not None:
types = _lazy_annotationlib.call_annotate_function(
original_annotate, _lazy_annotationlib.Format.FORWARDREF)
elif (original_annotate := annotationlib.get_annotate_from_class_namespace(ns)) is not None:
types = annotationlib.call_annotate_function(
original_annotate, annotationlib.Format.FORWARDREF)
field_names = list(types)

# For backward compatibility, type-check all the types at creation time
for typ in types.values():
_type_check(typ, "field annotation must be a type")

def annotate(format):
annos = _lazy_annotationlib.call_annotate_function(
annos = annotationlib.call_annotate_function(
original_annotate, format)
if format != _lazy_annotationlib.Format.STRING:
if format != annotationlib.Format.STRING:
return {key: _type_check(val, f"field {key} annotation must be a type")
for key, val in annos.items()}
return annos
Expand Down Expand Up @@ -3207,9 +3199,9 @@ def __new__(cls, name, bases, ns, total=True, closed=None,
if ns_annotations is not None:
own_annotate = None
own_annotations = ns_annotations
elif (own_annotate := _lazy_annotationlib.get_annotate_from_class_namespace(ns)) is not None:
own_annotations = _lazy_annotationlib.call_annotate_function(
own_annotate, _lazy_annotationlib.Format.FORWARDREF, owner=tp_dict
elif (own_annotate := annotationlib.get_annotate_from_class_namespace(ns)) is not None:
own_annotations = annotationlib.call_annotate_function(
own_annotate, annotationlib.Format.FORWARDREF, owner=tp_dict
)
else:
own_annotate = None
Expand Down Expand Up @@ -3276,20 +3268,20 @@ def __annotate__(format):
base_annotate = base.__annotate__
if base_annotate is None:
continue
base_annos = _lazy_annotationlib.call_annotate_function(
base_annos = annotationlib.call_annotate_function(
base_annotate, format, owner=base)
annos.update(base_annos)
if own_annotate is not None:
own = _lazy_annotationlib.call_annotate_function(
own = annotationlib.call_annotate_function(
own_annotate, format, owner=tp_dict)
if format != _lazy_annotationlib.Format.STRING:
if format != annotationlib.Format.STRING:
own = {
n: _type_check(tp, msg, module=tp_dict.__module__)
for n, tp in own.items()
}
elif format == _lazy_annotationlib.Format.STRING:
own = _lazy_annotationlib.annotations_to_string(own_annotations)
elif format in (_lazy_annotationlib.Format.FORWARDREF, _lazy_annotationlib.Format.VALUE):
elif format == annotationlib.Format.STRING:
own = annotationlib.annotations_to_string(own_annotations)
elif format in (annotationlib.Format.FORWARDREF, annotationlib.Format.VALUE):
own = own_checked_annotations
else:
raise NotImplementedError(format)
Expand Down Expand Up @@ -3886,7 +3878,7 @@ def __getattr__(attr):
are only created on-demand here.
"""
if attr == "ForwardRef":
obj = _lazy_annotationlib.ForwardRef
obj = annotationlib.ForwardRef
elif attr in {"Pattern", "Match"}:
import re
obj = _alias(getattr(re, attr), 1)
Expand Down
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