gh-141510: Add can_modify_dict() in dictobject.c - #144955
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vstinner merged 1 commit intoFeb 18, 2026
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can_modify_dict() is stricter than ASSERT_DICT_LOCKED() for frozendict. It uses PyUnstable_Object_IsUniquelyReferenced() which matters for free-threaded builds. Replace anydict_setitem_take2() with setitem_take2_lock_held(). It's no longer useful to have two functions.
corona10
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Just to share my thoughts:
- When we implement an xxx_lock_held function, I believe the goal is to ensure that developers declare critical sections properly through assertions. This change could cause confusion if someone starts calling xxx_lock_held, since it may require ASSERT_DICT_LOCKED for mutable collections but not for immutable ones.
- My personal view is that assertions should report consistent results whenever possible. As I understand it, PyUnstable_Object_IsUniquelyReferenced does not guarantee this. Its result depends on the runtime situation, which means we could miss buggy scenarios until they are triggered in CI.
It does not mean -1 on this change but prefer to listen other core devs opinion.
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corona10
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I changed my mind after DM with Victor.
Since the current assertion is only meaningful when the refcount is not 1.
cpython/Include/internal/pycore_critical_section.h
Lines 55 to 58 in c6a142f
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This change does multiple things:
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Merged. Thanks for your review @corona10. |
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can_modify_dict() is stricter than ASSERT_DICT_LOCKED() for frozendict. It uses PyUnstable_Object_IsUniquelyReferenced() which matters for free-threaded builds. Replace anydict_setitem_take2() with setitem_take2_lock_held(). It's no longer useful to have two functions.
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can_modify_dict() is stricter than ASSERT_DICT_LOCKED() for frozendict. It uses PyUnstable_Object_IsUniquelyReferenced() which matters for free-threaded builds. Replace anydict_setitem_take2() with setitem_take2_lock_held(). It's no longer useful to have two functions.
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can_modify_dict() is stricter than ASSERT_DICT_LOCKED() for frozendict. It uses PyUnstable_Object_IsUniquelyReferenced() which matters for free-threaded builds.
Replace anydict_setitem_take2() with setitem_take2_lock_held(). It's no longer useful to have two functions.