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, 5 insertions, 9 deletions

diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index 1888337..46e18c1 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -32,11 +32,6 @@
 
 #define PUTS(fd, str) _Py_write_noraise(fd, str, strlen(str))
 
-_Py_IDENTIFIER(enable);
-_Py_IDENTIFIER(fileno);
-_Py_IDENTIFIER(flush);
-_Py_IDENTIFIER(stderr);
-
 #ifdef HAVE_SIGACTION
 typedef struct sigaction _Py_sighandler_t;
 #else
@@ -155,7 +150,8 @@ faulthandler_get_fileno(PyObject **file_ptr)
     PyObject *file = *file_ptr;
 
     if (file == NULL || file == Py_None) {
-        file = _PySys_GetObjectId(&PyId_stderr);
+        PyThreadState *tstate = _PyThreadState_GET();
+        file = _PySys_GetAttr(tstate, &_Py_ID(stderr));
         if (file == NULL) {
             PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr");
             return -1;
@@ -178,7 +174,7 @@ faulthandler_get_fileno(PyObject **file_ptr)
         return fd;
     }
 
-    result = _PyObject_CallMethodIdNoArgs(file, &PyId_fileno);
+    result = PyObject_CallMethodNoArgs(file, &_Py_ID(fileno));
     if (result == NULL)
         return -1;
 
@@ -196,7 +192,7 @@ faulthandler_get_fileno(PyObject **file_ptr)
         return -1;
     }
 
-    result = _PyObject_CallMethodIdNoArgs(file, &PyId_flush);
+    result = PyObject_CallMethodNoArgs(file, &_Py_ID(flush));
     if (result != NULL)
         Py_DECREF(result);
     else {
@@ -1336,7 +1332,7 @@ faulthandler_init_enable(void)
         return -1;
     }
 
-    PyObject *res = _PyObject_CallMethodIdNoArgs(module, &PyId_enable);
+    PyObject *res = PyObject_CallMethodNoArgs(module, &_Py_ID(enable));
     Py_DECREF(module);
     if (res == NULL) {
         return -1;