[dependabot]

Bumps optree from 0.19.1 to 0.20.0.

Release notes

Sourced from optree's releases.

optree v0.20.0

Added

• Preserve dict insertion order on unflatten for the Python tree_flatten_one_level path mirroring the C++ path by @​XuehaiPan in #280.
• Add built-in frozendict support for Python 3.15+ (PEP 814), with PyTreeKind.FROZENDICT, optree.treespec_frozendict(), optree.treespec.frozendict(), and optree.typing.FrozenDict by @​XuehaiPan in #274.
• Migrate to Python_FIND_ABI for CMake's FindPython by @​XuehaiPan in #292.
• Add Python 3.15 and Python 3.15t support by @​XuehaiPan in #293.

Changed

• Update minimal version of typing-extensions to 4.10.0 for typing_extensions.TypeIs by @​XuehaiPan in #285.

Fixed

• Define Py_GIL_DISABLED for free-threaded debug builds on Windows when building the C extension to work around an upstream CMake FindPython bug by @​XuehaiPan in #285.
• Correct rare-case bugs from adversarial audit across deadlocks, caching, serialization, memory safety, and Python frontend by @​XuehaiPan in #290.

• Fix a deadlock when registering or unregistering a pytree node concurrently with flattening, caused by releasing the GIL while holding the registry lock by @​XuehaiPan in #290.
• Fix a deadlock when a duplicate registration or an unregistration of an unregistered type formats its error message, which runs the type's __repr__ while the registry lock is held and wedges any thread that is flattening by @​XuehaiPan in #290.
• Fix registering an already-registered collections.namedtuple subclass or PyStructSequence emitting the override warning even though the registration is rejected, which raised UserWarning instead of ValueError under warnings-as-errors by @​XuehaiPan in #290.
• Fix a deadlock when unregistering a pytree node drops the last reference to its flatten or unflatten function, so a __del__ or weakref callback re-entered the registry while its lock was held by @​XuehaiPan in #290.
• Fix a deadlock while flattening on free-threading builds, caused by acquiring the non-recursive dictionary insertion order lock twice by @​XuehaiPan in #290.
• Fix a spurious SystemError from optree._C.get_registry_size() when a concurrent registration slipped between its two reads by @​XuehaiPan in #290.
• Fix optree.tree_iter() hanging uninterruptibly when the is_leaf predicate or a custom flatten function advances the same iterator, now reported as a RuntimeError by @​XuehaiPan in #290.
• Fix the type caches handing an interpreter a value owned by another one, by keying them on the interpreter in addition to the type address by @​XuehaiPan in #290.
• Fix the type caches retaining entries for a finalized interpreter, which leaked immortal keys and could be inherited by a fresh interpreter reusing the same ID by @​XuehaiPan in #290.
• Fix a deadlock in the PyStructSequence field cache, caused by re-acquiring the GIL while still holding the cache lock by @​XuehaiPan in #290.
• Fix the type caches publishing an entry that a failed cleanup registration would orphan, leaving a value owned by an interpreter with no callback able to evict it, whether the publish preceded that registration or raced another thread still performing it by @​XuehaiPan in #290.
• Fix optree.structseq_fields() and the struct sequence accessors reporting the trailing hidden field names for unnamed sequence slots, by mapping each field to the slot its member offset names; the pure Python fallback, which cannot read those offsets, recovers the positions from a probe instance instead of assuming the unnamed slots trail the named ones by @​XuehaiPan in #290.
• Fix the treespec repr printing the raw unnamed-field marker as if it were a keyword argument, now rendered as <unnamed@N> by @​XuehaiPan in #290.
• Fix StructSequenceEntry reporting an unnamed sequence slot as field='unnamed field', which reads as a real field name, now reported by its index by @​XuehaiPan in #290.
• Fix PyTreeSpec.__setstate__() accepting a malformed state, which could read out of bounds or abort the interpreter when the treespec was later used by @​XuehaiPan in #290.
• Fix PyTreeSpec.__getstate__() returning the treespec's internal mutable containers, so mutating the pickled state corrupted an otherwise immutable treespec by @​XuehaiPan in #290.
• Fix PyTreeSpec.__setstate__() borrowing the key lists from the state it was given rather than copying them, so mutating that state afterwards silently reordered the restored treespec by @​XuehaiPan in #290.
• Fix pickling a PyTreeSpec with protocol 0 or 1 aborting the interpreter, by reducing through copyreg.__newobj__ by @​XuehaiPan in #290.
• Fix PyTreeSpec.compose(), PyTreeSpec.broadcast_to_common_suffix(), treespec_transform(), and treespec_from_collection() silently rebinding a custom node to a different registration when an empty namespace adopted a non-empty one by @​XuehaiPan in #290.
• Fix PyTreeSpec.broadcast_to_common_suffix() sorting the argument treespec's dictionary keys in place while building its key-mismatch error message, corrupting a treespec the caller still holds by @​XuehaiPan in #290.
• Fix the dictionary key order being lost when a treespec built under the global namespace is promoted to an insertion-ordered namespace by @​XuehaiPan in #290.
• Fix treespec_from_collection() on a leaf reporting an escalated UserWarning as a confusing SystemError, by checking the return value of PyErr_WarnEx() by @​XuehaiPan in #290.
• Fix treespec_from_collection() keeping the caller's namespace on a leaf or None root, which made otherwise identical treespecs compare unequal by @​XuehaiPan in #290.
• Fix treespec_is_prefix() and treespec_is_suffix() comparing against a stale subtree when a dictionary node's keys had been reordered by @​XuehaiPan in #290.
• Fix the tree iterator never reporting or clearing its is_leaf predicate to the garbage collector, leaking any reference cycle that passes through it by @​XuehaiPan in #290.
• Fix a list shrunk by an is_leaf predicate part way through flattening being read out of bounds on Python versions before 3.13.0a4, now raising IndexError by @​XuehaiPan in #290.
• Fix a reference cycle passing through a registered custom type not being collectable once the registry no longer holds the registration, by reporting the registration's members to the garbage collector when a treespec's own nodes hold every reference to it; a cycle spanning several treespecs remains uncollectable by @​XuehaiPan in #290.
• Fix a deeply nested treespec overflowing the native stack and crashing in treespec_paths(), treespec_accessors(), and PyTreeSpec.broadcast_to_common_suffix() instead of raising RecursionError by @​XuehaiPan in #290.
• Fix DataclassEntry and AttrsEntry resolving an integer entry against every declared field rather than the children the registration emitted, which returned the wrong attribute for a class holding a metadata or non-init field, now read from the record register_node() leaves on the class itself by @​XuehaiPan in #290.

... (truncated)

Changelog

Sourced from optree's changelog.

[0.20.0] - 2026-08-20

Added

• Preserve dict insertion order on unflatten for the Python tree_flatten_one_level path mirroring the C++ path by @​XuehaiPan in #280.
• Add built-in frozendict support for Python 3.15+ (PEP 814), with PyTreeKind.FROZENDICT, optree.treespec_frozendict(), optree.treespec.frozendict(), and optree.typing.FrozenDict by @​XuehaiPan in #274.
• Migrate to Python_FIND_ABI for CMake's FindPython by @​XuehaiPan in #292.
• Add Python 3.15 and Python 3.15t support by @​XuehaiPan in #293.

Changed

• Update minimal version of typing-extensions to 4.10.0 for typing_extensions.TypeIs by @​XuehaiPan in #285.

Fixed

• Define Py_GIL_DISABLED for free-threaded debug builds on Windows when building the C extension to work around an upstream CMake FindPython bug by @​XuehaiPan in #285.
• Fix a deadlock when registering or unregistering a pytree node concurrently with flattening, caused by releasing the GIL while holding the registry lock by @​XuehaiPan in #290.
• Fix a deadlock when a duplicate registration or an unregistration of an unregistered type formats its error message, which runs the type's __repr__ while the registry lock is held and wedges any thread that is flattening by @​XuehaiPan in #290.
• Fix registering an already-registered collections.namedtuple subclass or PyStructSequence emitting the override warning even though the registration is rejected, which raised UserWarning instead of ValueError under warnings-as-errors by @​XuehaiPan in #290.
• Fix a deadlock when unregistering a pytree node drops the last reference to its flatten or unflatten function, so a __del__ or weakref callback re-entered the registry while its lock was held by @​XuehaiPan in #290.
• Fix a deadlock while flattening on free-threading builds, caused by acquiring the non-recursive dictionary insertion order lock twice by @​XuehaiPan in #290.
• Fix a spurious SystemError from optree._C.get_registry_size() when a concurrent registration slipped between its two reads by @​XuehaiPan in #290.
• Fix optree.tree_iter() hanging uninterruptibly when the is_leaf predicate or a custom flatten function advances the same iterator, now reported as a RuntimeError by @​XuehaiPan in #290.
• Fix the type caches handing an interpreter a value owned by another one, by keying them on the interpreter in addition to the type address by @​XuehaiPan in #290.
• Fix the type caches retaining entries for a finalized interpreter, which leaked immortal keys and could be inherited by a fresh interpreter reusing the same ID by @​XuehaiPan in #290.
• Fix a deadlock in the PyStructSequence field cache, caused by re-acquiring the GIL while still holding the cache lock by @​XuehaiPan in #290.
• Fix the type caches publishing an entry that a failed cleanup registration would orphan, leaving a value owned by an interpreter with no callback able to evict it, whether the publish preceded that registration or raced another thread still performing it by @​XuehaiPan in #290.
• Fix optree.structseq_fields() and the struct sequence accessors reporting the trailing hidden field names for unnamed sequence slots, by mapping each field to the slot its member offset names; the pure Python fallback, which cannot read those offsets, recovers the positions from a probe instance instead of assuming the unnamed slots trail the named ones by @​XuehaiPan in #290.
• Fix the treespec repr printing the raw unnamed-field marker as if it were a keyword argument, now rendered as <unnamed@N> by @​XuehaiPan in #290.
• Fix StructSequenceEntry reporting an unnamed sequence slot as field='unnamed field', which reads as a real field name, now reported by its index by @​XuehaiPan in #290.
• Fix PyTreeSpec.__setstate__() accepting a malformed state, which could read out of bounds or abort the interpreter when the treespec was later used by @​XuehaiPan in #290.
• Fix PyTreeSpec.__getstate__() returning the treespec's internal mutable containers, so mutating the pickled state corrupted an otherwise immutable treespec by @​XuehaiPan in #290.
• Fix PyTreeSpec.__setstate__() borrowing the key lists from the state it was given rather than copying them, so mutating that state afterwards silently reordered the restored treespec by @​XuehaiPan in #290.
• Fix pickling a PyTreeSpec with protocol 0 or 1 aborting the interpreter, by reducing through copyreg.__newobj__ by @​XuehaiPan in #290.
• Fix PyTreeSpec.compose(), PyTreeSpec.broadcast_to_common_suffix(), treespec_transform(), and treespec_from_collection() silently rebinding a custom node to a different registration when an empty namespace adopted a non-empty one by @​XuehaiPan in #290.
• Fix PyTreeSpec.broadcast_to_common_suffix() sorting the argument treespec's dictionary keys in place while building its key-mismatch error message, corrupting a treespec the caller still holds by @​XuehaiPan in #290.
• Fix the dictionary key order being lost when a treespec built under the global namespace is promoted to an insertion-ordered namespace by @​XuehaiPan in #290.
• Fix treespec_from_collection() on a leaf reporting an escalated UserWarning as a confusing SystemError, by checking the return value of PyErr_WarnEx() by @​XuehaiPan in #290.
• Fix treespec_from_collection() keeping the caller's namespace on a leaf or None root, which made otherwise identical treespecs compare unequal by @​XuehaiPan in #290.
• Fix treespec_is_prefix() and treespec_is_suffix() comparing against a stale subtree when a dictionary node's keys had been reordered by @​XuehaiPan in #290.
• Fix the tree iterator never reporting or clearing its is_leaf predicate to the garbage collector, leaking any reference cycle that passes through it by @​XuehaiPan in #290.
• Fix a list shrunk by an is_leaf predicate part way through flattening being read out of bounds on Python versions before 3.13.0a4, now raising IndexError by @​XuehaiPan in #290.
• Fix a reference cycle passing through a registered custom type not being collectable once the registry no longer holds the registration, by reporting the registration's members to the garbage collector when a treespec's own nodes hold every reference to it; a cycle spanning several treespecs remains uncollectable by @​XuehaiPan in #290.
• Fix a deeply nested treespec overflowing the native stack and crashing in treespec_paths(), treespec_accessors(), and PyTreeSpec.broadcast_to_common_suffix() instead of raising RecursionError by @​XuehaiPan in #290.
• Fix DataclassEntry and AttrsEntry resolving an integer entry against every declared field rather than the children the registration emitted, which returned the wrong attribute for a class holding a metadata or non-init field, now read from the record register_node() leaves on the class itself by @​XuehaiPan in #290.
• Fix optree.dataclasses.register_node() and optree.integrations.attrs.register_node() leaving a class in a half-registered state that could never be registered again: the registry entry and the field marker are now committed together, and a failure of either rolls the other back by @​XuehaiPan in #290.
• Fix optree.dataclasses.register_node() silently dropping InitVar pseudo-fields, which are neither children nor metadata and cannot round-trip, now rejected with a pointer to the generic API by @​XuehaiPan in #290.
• Fix tree_broadcast_common() and broadcast_common() applying the caller's is_leaf predicate to an internal sentinel tree, which could raise from the predicate or collapse a filled subtree and under-replicate by @​XuehaiPan in #290.
• Fix PyTreeEntry equality and hashing comparing the bytecode of __call__() and codify() rather than the methods themselves, so two entry classes that happened to share an implementation compared equal by @​XuehaiPan in #290.
• Fix PyTreeAccessor overriding __eq__() while inheriting tuple.__ne__(), so comparing one with a plain tuple of equal entries reported False for both == and != by @​XuehaiPan in #290.

... (truncated)

Commits

• 6b2a48f ver: bump version to 0.20.0
• 45bba86 deps(python): enable Python 3.15 and Python 3.15t support (#293)
• 2928b52 feat(setup): migrate to Python_FIND_ABI for CMake's FindPython (#292)
• 5336257 feat: add built-in frozendict support for Python 3.15+ (#274)
• 6df80b1 deps(workflows): bump pypa/cibuildwheel from 4.1 to 4.2
• d34f302 fix(ops,accessors,utils): correct field selection, broadcasting and total ord...
• 7bc8b3a fix(treespec): correct namespace merging, GC reporting and walker safety
• 2ba4945 fix(treespec): map struct sequence fields by offset and validate pickled state
• 879c756 refactor(pytypes): extract WeakKeyCache and make the type caches interpreter-...
• 4685aa5 fix(registry,traversal): correct lock ordering and re-entrancy
• Additional commits viewable in compare view

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