bpo-39947: Hide implementation detail of trashcan macros (GH-18971)

Py_TRASHCAN_BEGIN_CONDITION and Py_TRASHCAN_END macro no longer
access PyThreadState attributes, but call new private
_PyTrash_begin() and _PyTrash_end() functions which hide
implementation details.

1 files changed, 24 insertions, 0 deletions

diff --git a/Objects/object.c b/Objects/object.c
index 72c4189..e6d0da1 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -2116,6 +2116,30 @@ _PyTrash_thread_destroy_chain(void)
 }
 
 
+int
+_PyTrash_begin(PyThreadState *tstate, PyObject *op)
+{
+    if (tstate->trash_delete_nesting >= PyTrash_UNWIND_LEVEL) {
+        /* Store the object (to be deallocated later) and jump past
+         * Py_TRASHCAN_END, skipping the body of the deallocator */
+        _PyTrash_thread_deposit_object(op);
+        return 1;
+    }
+    ++tstate->trash_delete_nesting;
+    return 0;
+}
+
+
+void
+_PyTrash_end(PyThreadState *tstate)
+{
+    --tstate->trash_delete_nesting;
+    if (tstate->trash_delete_later && tstate->trash_delete_nesting <= 0) {
+        _PyTrash_thread_destroy_chain();
+    }
+}
+
+
 void _Py_NO_RETURN
 _PyObject_AssertFailed(PyObject *obj, const char *expr, const char *msg,
                        const char *file, int line, const char *function)