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gh-146553: Fix infinite loop in typing.get_type_hints() on circular __wrapped__ #146554

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gh-146553: Fix infinite loop in typing.get_type_hints() on circular __wrapped__ #146554

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61a821b
gh-146553: Fix infinite loop in typing.get_type_hints() on circular _…
raminfp Mar 28, 2026
4e9afee
gh-146553: Use inspect.unwrap() for cycle detection instead of custom…
raminfp Mar 28, 2026
e205384
gh-146553: Use _lazy_load_unwrap() helper instead of local import in …
raminfp Mar 30, 2026
27c948d
gh-146553: Replace _lazy_load_* helpers with _LazyInspect for lazy in…
raminfp Mar 30, 2026
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14 changes: 12 additions & 2 deletions Lib/typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1973,6 +1973,17 @@ def _lazy_load_getattr_static():
_cleanups.append(_lazy_load_getattr_static.cache_clear)


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@functools.cache
def _lazy_load_unwrap():
# Import unwrap lazily so as not to slow down the import of typing.py
# Cache the result so we don't slow down get_type_hints() unnecessarily
from inspect import unwrap
return unwrap


_cleanups.append(_lazy_load_unwrap.cache_clear)
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@picnixz picnixz Mar 30, 2026

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I think we can just use lazy import inspect now and get rid of those lazy load stuff?

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@AlexWaygood AlexWaygood Mar 30, 2026

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There was some controversy about using PEP 810 too widely in the stdlib https://discuss.python.org/t/concerns-about-x-lazy-imports-none/106203

I don't have a strong opinion myself, to be clear

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@raminfp raminfp Mar 30, 2026

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@picnixz Done, replaced both _lazy_load_getattr_static and _lazy_load_unwrap with a _LazyInspect class following the existing _LazyAnnotationLib pattern already in the file.

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@picnixz picnixz Mar 30, 2026

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There was some controversy about using PEP 810 too widely in the stdlib

Jelle said he was fine so I think we can do the switch unless it's breaking something. @raminfp please check that the concerns expressed in the DPO thread are not concerns, but do so without using an LLM.



def _pickle_psargs(psargs):
return ParamSpecArgs, (psargs.__origin__,)

Expand Down Expand Up @@ -2485,8 +2496,7 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False,
globalns = obj.__dict__
else:
# Find globalns for the unwrapped object.
import inspect
nsobj = inspect.unwrap(obj)
nsobj = _lazy_load_unwrap()(obj)
globalns = getattr(nsobj, '__globals__', {})
if localns is None:
localns = globalns
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