Inventory CPython dependencies

For a Python-version change, start with the native extensions listed in setup.py and their CMake/Cargo inputs. Search tracked C, C++, Cython, and Rust sources, including declarations in .pxd files and code under both ddtrace/ and src/.

rg -n -g '*.{c,cc,cpp,h,hh,hpp,pyx,pxd,rs}' \
  'Python\.h|cpython[/.]|internal/pycore|pyo3(_ffi|::ffi)' ddtrace src
rg -n -g '*.{c,cc,cpp,h,hh,hpp,pyx,pxd,rs}' \
  'PyFrameObject|PyThreadState|PyInterpreterState|PyCodeObject|_PyInterpreterFrame' ddtrace src
rg -n -g '*.{c,cc,cpp,h,hh,hpp,pyx,pxd,rs}' \
  'PyGenObject|PyCoro_CheckExact|PyAsyncGenASend|FutureObj|TaskObj' ddtrace src

These searches are seeds, not an exhaustive API detector. Follow wrappers, aliases, generated bindings, struct field reads, and version guards in the affected extensions. Distinguish vendored code from code owned here, and public APIs from unstable internals.

Include generator/coroutine state, async-generator wrappers, and asyncio task/future layouts. For examples of copied layouts and version guards, inspect ddtrace/internal/datadog/profiling/stack/echion/echion/cpython/tasks.h and its callers.

Distinguish CPython's public Include/ headers, CPython-specific Include/cpython/ headers, and private Include/internal/pycore*.h headers. Check the target version's guards and include order for Py_BUILD_CORE; see ddtrace/profiling/collector/_memalloc_frame.h for a local example.

Within each affected extension, find field reads and layout-dependent copies as well as API calls:

rg -n -g '*.{c,cc,cpp,h,hh,hpp,pyx,pxd,rs}' -- \
  '(->|\.)(f_|co_|gi_|cr_|ag_|task_|future_)|offsetof\(|sizeof\(|copy_type\(' <affected-native-directory>

Follow each matching object's type back to its declaration, including aliases and locally copied CPython structs. Check fields accessed through macros or helper functions too; the pattern above does not cover every field name or access form.

Record each relevant header, symbol or field, source location, supported-version guard, and lifetime/locking assumption. Pass that inventory to compare-cpython-versions; avoid maintaining a static symbol list.