Check for ref counting bugs in debug mode caused by immortal objects. #94851
Description
With #90699, the identifiers are statically allocated and are immortal. This makes it easy to make reference counting mistakes as they are not detected and cause negative ref count in _Py_RefTotal.
On my machine the reference count is negative because of missing incref on &_Py_STR(empty):
@kumaraditya303 ➜ /workspaces/cpython (main) $ ./python -I -X showrefcount -c pass
[-1 refs, 0 blocks]PR #94850 fixes this issue.
To make it easy to discover reference counting issue, I propose to after each runtime finalization check that all the static allocated immortal objects have ref count of 999999999 otherwise _PyObject_Dump can be used to output the object and abort the process in debug mode and this will help prevent these kinds of issues of "unstable" ref count.