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Py_TRACE_REFS is not compatible with Py_LIMITED_API #108634
Description
Bug report
Checklist
- I am confident this is a bug in CPython, not a bug in a third-party project
- I have searched the CPython issue tracker,
and am confident this bug has not been reported before
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
No response
A clear and concise description of the bug:
Trying to build a C extension targetting the limited C API (defining Py_LIMITED_API) fails if Python is configured with ./configure --with-trace-refs. Example with PR #108573:
In file included from ./Include/Python.h:44,
from ./Modules/_stat.c:16:
./Include/object.h:62:4: error: #error Py_LIMITED_API is incompatible with Py_TRACE_REFS
62 | # error Py_LIMITED_API is incompatible with Py_TRACE_REFS
| ^~~~~
make: *** [Makefile:3194: Modules/_stat.o] Error 1
The #error comes from Include/object.h:
#if defined(Py_LIMITED_API) && defined(Py_TRACE_REFS)
# error Py_LIMITED_API is incompatible with Py_TRACE_REFS
#endifThe problem is that the PyObject ABI is different: Py_TRACE_REFS adds two members to PyObject structure:
PyObject *_ob_next;
PyObject *_ob_prev;One solution to make Py_TRACE_REFS compatible with Py_LIMITED_API would be to not add these two members to PyObject, but store the double-linked list outside PyObject. Store it in a different structure, so PyObject stays ABI compatible.
Activity
erlend-aasland commentedon Aug 29, 2023
See also #63083 and #73104
pythongh-108634: Use a hashtable for Py_TRACE_REFS
pythongh-108634: Use a hashtable for Py_TRACE_REFS
pythongh-108634: Py_TRACE_REFS uses a hash table
pythongh-108634: Py_TRACE_REFS uses a hash table
pythongh-108634: Py_TRACE_REFS uses a hash table
pythongh-108634: Py_TRACE_REFS uses a hash table
pythongh-108634: Py_TRACE_REFS uses a hash table
gh-108634: Py_TRACE_REFS uses a hash table (#108663)
pythongh-108634: init_interpreter() returns Py_Status
pythongh-108634: init_interpreter() returns Py_Status
pythongh-108634: init_interpreter() returns Py_Status
pythongh-108634: PyInterpreterState_New() no longer calls Py_FatalErr…
pythongh-108634: PyInterpreterState_New() no longer calls Py_FatalErr…
pythongh-108634: PyInterpreterState_New() no longer calls Py_FatalErr…
pythongh-108634: Add _PyInterpreterState_New() function
gh-108634: PyInterpreterState_New() no longer calls Py_FatalError() (#…