bpo-46541: Replace core use of _Py_IDENTIFIER() with statically initialized global objects. (gh-30928)

We're no longer using _Py_IDENTIFIER() (or _Py_static_string()) in any core CPython code.  It is still used in a number of non-builtin stdlib modules.

The replacement is: PyUnicodeObject (not pointer) fields under _PyRuntimeState, statically initialized as part of _PyRuntime.  A new _Py_GET_GLOBAL_IDENTIFIER() macro facilitates lookup of the fields (along with _Py_GET_GLOBAL_STRING() for non-identifier strings).

https://bugs.python.org/issue46541#msg411799 explains the rationale for this change.

The core of the change is in:

* (new) Include/internal/pycore_global_strings.h - the declarations for the global strings, along with the macros
* Include/internal/pycore_runtime_init.h - added the static initializers for the global strings
* Include/internal/pycore_global_objects.h - where the struct in pycore_global_strings.h is hooked into _PyRuntimeState
* Tools/scripts/generate_global_objects.py - added generation of the global string declarations and static initializers

I've also added a --check flag to generate_global_objects.py (along with make check-global-objects) to check for unused global strings.  That check is added to the PR CI config.

The remainder of this change updates the core code to use _Py_GET_GLOBAL_IDENTIFIER() instead of _Py_IDENTIFIER() and the related _Py*Id functions (likewise for _Py_GET_GLOBAL_STRING() instead of _Py_static_string()).  This includes adding a few functions where there wasn't already an alternative to _Py*Id(), replacing the _Py_Identifier * parameter with PyObject *.

The following are not changed (yet):

* stop using _Py_IDENTIFIER() in the stdlib modules
* (maybe) get rid of _Py_IDENTIFIER(), etc. entirely -- this may not be doable as at least one package on PyPI using this (private) API
* (maybe) intern the strings during runtime init

https://bugs.python.org/issue46541

1 files changed, 2 insertions, 2 deletions

diff --git a/Modules/_operator.c b/Modules/_operator.c
index b3a8bef2eae..10adabcbf0e 100644
--- a/Modules/_operator.c
+++ b/Modules/_operator.c
@@ -1,5 +1,6 @@
 #include "Python.h"
 #include "pycore_moduleobject.h"  // _PyModule_GetState()
+#include "pycore_runtime.h"       // _Py_ID()
 #include "clinic/_operator.c.h"
 
 typedef struct {
@@ -1693,11 +1694,10 @@ methodcaller_reduce(methodcallerobject *mc, PyObject *Py_UNUSED(ignored))
         PyObject *constructor;
         PyObject *newargs[2];
 
-        _Py_IDENTIFIER(partial);
         functools = PyImport_ImportModule("functools");
         if (!functools)
             return NULL;
-        partial = _PyObject_GetAttrId(functools, &PyId_partial);
+        partial = PyObject_GetAttr(functools, &_Py_ID(partial));
         Py_DECREF(functools);
         if (!partial)
             return NULL;