[3.12] gh-124785: Revert "[3.12] gh-116510: Fix a crash due to shared immortal interned strings. (gh-124541)" (#124814)

Revert "[3.12] gh-116510: Fix a crash due to shared immortal interned strings. (gh-124541)"

This reverts commit 5dd07eb.

Author: nascheme

Misc/NEWS.d/next/Core_and_Builtins/2024-09-25-12-37-58.gh-issue-116510.WeBAx1.rst

@@ -286,37 +286,13 @@ hashtable_unicode_compare(const void *key1, const void *key2)
     }
 }
 
-/* Return true if this interpreter should share the main interpreter's
-   intern_dict.  That's important for interpreters which load basic
-   single-phase init extension modules (m_size == -1).  There could be interned
-   immortal strings that are shared between interpreters, due to the
-   PyDict_Update(mdict, m_copy) call in import_find_extension().
-
-   It's not safe to deallocate those strings until all interpreters that
-   potentially use them are freed.  By storing them in the main interpreter, we
-   ensure they get freed after all other interpreters are freed.
-*/
-static bool
-has_shared_intern_dict(PyInterpreterState *interp)
-{
-    PyInterpreterState *main_interp = _PyInterpreterState_Main();
-    return interp != main_interp  && interp->feature_flags & Py_RTFLAGS_USE_MAIN_OBMALLOC;
-}
-
 static int
 init_interned_dict(PyInterpreterState *interp)
 {
     assert(get_interned_dict(interp) == NULL);
-    PyObject *interned;
-    if (has_shared_intern_dict(interp)) {
-        interned = get_interned_dict(_PyInterpreterState_Main());
-        Py_INCREF(interned);
-    }
-    else {
-        interned = PyDict_New();
-        if (interned == NULL) {
-            return -1;
-        }
+    PyObject *interned = interned = PyDict_New();
+    if (interned == NULL) {
+        return -1;
     }
     _Py_INTERP_CACHED_OBJECT(interp, interned_strings) = interned;
     return 0;
@@ -327,10 +303,7 @@ clear_interned_dict(PyInterpreterState *interp)
 {
     PyObject *interned = get_interned_dict(interp);
     if (interned != NULL) {
-        if (!has_shared_intern_dict(interp)) {
-            // only clear if the dict belongs to this interpreter
-            PyDict_Clear(interned);
-        }
+        PyDict_Clear(interned);
         Py_DECREF(interned);
         _Py_INTERP_CACHED_OBJECT(interp, interned_strings) = NULL;
     }
@@ -15163,13 +15136,6 @@ _PyUnicode_ClearInterned(PyInterpreterState *interp)
     }
     assert(PyDict_CheckExact(interned));
 
-    if (has_shared_intern_dict(interp)) {
-        // the dict doesn't belong to this interpreter, skip the debug
-        // checks on it and just clear the pointer to it
-        clear_interned_dict(interp);
-        return;
-    }
-
 #ifdef INTERNED_STATS
     fprintf(stderr, "releasing %zd interned strings\n",
             PyDict_GET_SIZE(interned));
@@ -15688,10 +15654,8 @@ _PyUnicode_Fini(PyInterpreterState *interp)
 {
     struct _Py_unicode_state *state = &interp->unicode;
 
-    if (!has_shared_intern_dict(interp)) {
-        // _PyUnicode_ClearInterned() must be called before _PyUnicode_Fini()
-        assert(get_interned_dict(interp) == NULL);
-    }
+    // _PyUnicode_ClearInterned() must be called before _PyUnicode_Fini()
+    assert(get_interned_dict(interp) == NULL);
 
     _PyUnicode_FiniEncodings(&state->fs_codec);