Change event code to use gdbpy_ref

This changes the event code in the Python layer to use
gdbpy_ref, simplifying the logic in many places.

It also changes evpy_emit_event not to steal a reference to its
argument.  This is simpler to do now that gdbpy_ref is in use;
it's also a reasonable cleanup in its own right.  While doing this I
realized that evpy_emit_event should not be calling gdbpy_print_stack
(all the outermost callers do this if needed), so I removed this as
well.

2017-01-10  Tom Tromey  <tom@tromey.com>

	* python/py-threadevent.c (create_thread_event_object): Use
	gdbpy_ref.
	* python/py-stopevent.c (create_stop_event_object): Simplify.
	(emit_stop_event): Use gdbpy_ref.
	* python/py-signalevent.c (create_signal_event_object): Use
	gdbpy_ref.
	* python/py-newobjfileevent.c (create_new_objfile_event_object)
	(emit_new_objfile_event, create_clear_objfiles_event_object)
	(emit_clear_objfiles_event): Use gdbpy_ref.
	* python/py-infevents.c (create_inferior_call_event_object)
	(create_register_changed_event_object)
	(create_memory_changed_event_object, emit_inferior_call_event)
	(emit_memory_changed_event, emit_register_changed_event): Use
	gdbpy_ref.
	* python/py-exitedevent.c (create_exited_event_object)
	(emit_exited_event): Use gdbpy_ref.
	* python/py-event.h (evpy_emit_event): Remove
	CPYCHECKER_STEALS_REFERENCE_TO_ARG annotation.
	* python/py-event.c (evpy_emit_event): Use gdbpy_ref.
	* python/py-continueevent.c (emit_continue_event): Use
	gdbpy_ref.
	* python/py-breakpoint.c (gdbpy_breakpoint_created)
	(gdbpy_breakpoint_deleted, gdbpy_breakpoint_modified): Use
	gdbpy_ref.
	* python/py-bpevent.c (create_breakpoint_event_object): Use
	gdbpy_ref.

1 files changed, 20 insertions, 34 deletions

diff --git a/gdb/python/py-stopevent.c b/gdb/python/py-stopevent.c
index 640d99a..b87ebda 100644
--- a/gdb/python/py-stopevent.c
+++ b/gdb/python/py-stopevent.c
@@ -23,16 +23,7 @@
 PyObject *
 create_stop_event_object (PyTypeObject *py_type)
 {
-  PyObject *stop_event_obj = create_thread_event_object (py_type);
-
-  if (!stop_event_obj)
-    goto fail;
-
-  return stop_event_obj;
-
-  fail:
-   Py_XDECREF (stop_event_obj);
-   return NULL;
+  return create_thread_event_object (py_type);
 }
 
 /* Callback observers when a stop event occurs.  This function will create a
@@ -45,8 +36,8 @@ create_stop_event_object (PyTypeObject *py_type)
 int
 emit_stop_event (struct bpstats *bs, enum gdb_signal stop_signal)
 {
-  PyObject *stop_event_obj = NULL; /* Appease GCC warning.  */
-  PyObject *list = NULL;
+  gdbpy_ref stop_event_obj;
+  gdbpy_ref list;
   PyObject *first_bp = NULL;
   struct bpstats *current_bs;
 
@@ -64,13 +55,13 @@ emit_stop_event (struct bpstats *bs, enum gdb_signal stop_signal)
 
           if (list == NULL)
             {
-              list = PyList_New (0);
-              if (!list)
-                goto fail;
+              list.reset (PyList_New (0));
+              if (list == NULL)
+		return -1;
             }
 
-          if (PyList_Append (list, current_py_bp))
-            goto fail;
+          if (PyList_Append (list.get (), current_py_bp))
+	    return -1;
 
           if (first_bp == NULL)
             first_bp = current_py_bp;
@@ -79,36 +70,31 @@ emit_stop_event (struct bpstats *bs, enum gdb_signal stop_signal)
 
   if (list != NULL)
     {
-      stop_event_obj = create_breakpoint_event_object (list, first_bp);
-      if (!stop_event_obj)
-        goto fail;
-      Py_DECREF (list);
+      stop_event_obj.reset (create_breakpoint_event_object (list.get (),
+							    first_bp));
+      if (stop_event_obj == NULL)
+	return -1;
     }
 
   /* Check if the signal is "Signal 0" or "Trace/breakpoint trap".  */
   if (stop_signal != GDB_SIGNAL_0
       && stop_signal != GDB_SIGNAL_TRAP)
     {
-      stop_event_obj =
-	  create_signal_event_object (stop_signal);
-      if (!stop_event_obj)
-	goto fail;
+      stop_event_obj.reset (create_signal_event_object (stop_signal));
+      if (stop_event_obj == NULL)
+	return -1;
     }
 
   /* If all fails emit an unknown stop event.  All event types should
      be known and this should eventually be unused.  */
-  if (!stop_event_obj)
+  if (stop_event_obj == NULL)
     {
-      stop_event_obj = create_stop_event_object (&stop_event_object_type);
-      if (!stop_event_obj)
-        goto fail;
+      stop_event_obj.reset (create_stop_event_object (&stop_event_object_type));
+      if (stop_event_obj == NULL)
+	return -1;
     }
 
-  return evpy_emit_event (stop_event_obj, gdb_py_events.stop);
-
- fail:
-  Py_XDECREF (list);
-  return -1;
+  return evpy_emit_event (stop_event_obj.get (), gdb_py_events.stop);
 }
 
 GDBPY_NEW_EVENT_TYPE (stop,