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Fix two problems found with PyPy 3.12: - Deallocating a py::dynamic_attr() instance aborted, because PyPy 3.12's _PyObject_GetDictPtr() cannot be called from tp_dealloc. Read the dict slot from tp_dictoffset on PyPy instead. - memoryview::from_buffer() passed temporary shape/strides arrays, which PyPy keeps without copying. Use PyPy's inline _shape/_strides arrays. Assisted-by: ClaudeCode:claude-opus-5-5
A later PyPy GC at an arbitrary point can run the Python-calling destructor and abort. Assisted-by: ClaudeCode:claude-opus-5-5
henryiii
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October 7, 2026 19:16
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Description
Test PyPy 8.0.0 in CI on both 3.11 and 3.12. PyPy 3.12 found two bugs:
py::dynamic_attr()instance aborted with "Invalid usage of a dying CPython object". PyPy 3.12's_PyObject_GetDictPtr()now publishes the dict into the C slot and cannot be called fromtp_dealloc(on 3.11 it always returned NULL). On PyPy, pybind11 now reads the slot fromtp_dictoffset.test_mi_dynamic_attributesnow runs the GC so that the crash is deterministic.memoryview::from_buffer()passes temporary shape/strides arrays. PyPy (8.0.0 and older) keeps these pointers without copying them unless they point to the inline_shape/_stridesarrays ofPy_buffer. On 3.12 this gave aMemoryError. On PyPy, pybind11 now copies the values into those arrays. Upstream PyPy fixed this on the py3.12 branch after 8.0.0.I ran the full test suite locally on macOS with PyPy 3.11 and 3.12 (8.0.0).
Suggested changelog entry:
py::dynamic_attr()instances and a dangling shape/strides pointer inmemoryview::from_buffer()on PyPy.