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, 4 insertions, 7 deletions

diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index dd215e8..8b1cff5 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -72,8 +72,6 @@ typedef struct {
 
 PyTypeObject PyFileIO_Type;
 
-_Py_IDENTIFIER(name);
-
 #define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
 
 /* Forward declarations */
@@ -146,9 +144,8 @@ _io_FileIO_close_impl(fileio *self)
     PyObject *res;
     PyObject *exc, *val, *tb;
     int rc;
-    _Py_IDENTIFIER(close);
-    res = _PyObject_CallMethodIdOneArg((PyObject*)&PyRawIOBase_Type,
-                                       &PyId_close, (PyObject *)self);
+    res = PyObject_CallMethodOneArg((PyObject*)&PyRawIOBase_Type,
+                                     &_Py_ID(close), (PyObject *)self);
     if (!self->closefd) {
         self->fd = -1;
         return res;
@@ -476,7 +473,7 @@ _Py_COMP_DIAG_POP
     _setmode(self->fd, O_BINARY);
 #endif
 
-    if (_PyObject_SetAttrId((PyObject *)self, &PyId_name, nameobj) < 0)
+    if (PyObject_SetAttr((PyObject *)self, &_Py_ID(name), nameobj) < 0)
         goto error;
 
     if (self->appending) {
@@ -1085,7 +1082,7 @@ fileio_repr(fileio *self)
     if (self->fd < 0)
         return PyUnicode_FromFormat("<_io.FileIO [closed]>");
 
-    if (_PyObject_LookupAttrId((PyObject *) self, &PyId_name, &nameobj) < 0) {
+    if (_PyObject_LookupAttr((PyObject *) self, &_Py_ID(name), &nameobj) < 0) {
         return NULL;
     }
     if (nameobj == NULL) {