Change thread_to_thread_object to return a new reference

This changes thread_to_thread_object to return a new reference and
fixes up all the callers.

gdb/ChangeLog
2018-09-16  Tom Tromey  <tom@tromey.com>

	* python/python-internal.h (thread_to_thread_object): Change
	return type.
	* python/py-inferior.c (thread_to_thread_object): Return a new
	reference.
	(infpy_thread_from_thread_handle): Update.
	* python/py-infthread.c (gdbpy_selected_thread): Update.
	* python/py-stopevent.c (create_stop_event_object): Update.
	* python/py-threadevent.c (py_get_event_thread): Return a new
	reference.
	(py_get_event_thread): Update.
	* python/py-event.h (py_get_event_thread): Change return type.
	* python/py-continueevent.c (create_continue_event_object):
	Update.

gdb/ChangeLog

@@ -1,3 +1,19 @@
+2018-09-16  Tom Tromey  <tom@tromey.com>
+
+	* python/python-internal.h (thread_to_thread_object): Change
+	return type.
+	* python/py-inferior.c (thread_to_thread_object): Return a new
+	reference.
+	(infpy_thread_from_thread_handle): Update.
+	* python/py-infthread.c (gdbpy_selected_thread): Update.
+	* python/py-stopevent.c (create_stop_event_object): Update.
+	* python/py-threadevent.c (py_get_event_thread): Return a new
+	reference.
+	(py_get_event_thread): Update.
+	* python/py-event.h (py_get_event_thread): Change return type.
+	* python/py-continueevent.c (create_continue_event_object):
+	Update.
+
 2018-09-16  Tom Tromey  <tom@tromey.com>
 
 	* python/py-progspace.c (pspy_get_objfiles): Update.

gdb/python/py-continueevent.c

@@ -32,12 +32,13 @@
 static gdbpy_ref<>
 create_continue_event_object (ptid_t ptid)
 {
-  PyObject *py_thr = py_get_event_thread (ptid);
+  gdbpy_ref<> py_thr = py_get_event_thread (ptid);
 
   if (py_thr == nullptr)
     return nullptr;
 
-  return create_thread_event_object (&continue_event_object_type, py_thr);
+  return create_thread_event_object (&continue_event_object_type,
+				     py_thr.get ());
 }
 
 /* Callback function which notifies observers when a continue event occurs.

gdb/python/py-event.h

@@ -68,9 +68,8 @@ extern gdbpy_ref<> create_event_object (PyTypeObject *py_type);
    running in non-stop mode then the event is thread specific, otherwise
    it is process wide.
    This function returns the currently stopped thread in non-stop mode and
-   Py_None otherwise.  In each case it returns a borrowed reference.  */
-extern PyObject *py_get_event_thread (ptid_t ptid)
-  CPYCHECKER_RETURNS_BORROWED_REF;
+   Py_None otherwise.  */
+extern gdbpy_ref<> py_get_event_thread (ptid_t ptid);
 
 extern gdbpy_ref<> create_thread_event_object (PyTypeObject *py_type,
 					       PyObject *thread);

gdb/python/py-inferior.c

@@ -306,7 +306,7 @@ find_inferior_object (int pid)
   return NULL;
 }
 
-thread_object *
+gdbpy_ref<>
 thread_to_thread_object (thread_info *thr)
 {
   gdbpy_ref<inferior_object> inf_obj (inferior_to_inferior_object (thr->inf));
@@ -317,7 +317,7 @@ thread_to_thread_object (thread_info *thr)
        thread != NULL;
        thread = thread->next)
     if (thread->thread_obj->thread == thr)
-      return thread->thread_obj;
+      return gdbpy_ref<>::new_reference ((PyObject *) thread->thread_obj);
 
   return NULL;
 }
@@ -832,7 +832,7 @@ infpy_is_valid (PyObject *self, PyObject *args)
 static PyObject *
 infpy_thread_from_thread_handle (PyObject *self, PyObject *args, PyObject *kw)
 {
-  PyObject *handle_obj, *result;
+  PyObject *handle_obj;
   inferior_object *inf_obj = (inferior_object *) self;
   static const char *keywords[] = { "thread_handle", NULL };
 
@@ -841,8 +841,6 @@ infpy_thread_from_thread_handle (PyObject *self, PyObject *args, PyObject *kw)
   if (! gdb_PyArg_ParseTupleAndKeywords (args, kw, "O", keywords, &handle_obj))
     return NULL;
 
-  result = Py_None;
-
   if (!gdbpy_is_value_object (handle_obj))
     {
       PyErr_SetString (PyExc_TypeError,
@@ -850,8 +848,8 @@ infpy_thread_from_thread_handle (PyObject *self, PyObject *args, PyObject *kw)
 
       return NULL;
     }
-  else
-    {
+
+  gdbpy_ref<> result;
   TRY
     {
       struct thread_info *thread_info;
@@ -859,20 +857,18 @@ infpy_thread_from_thread_handle (PyObject *self, PyObject *args, PyObject *kw)
 
       thread_info = find_thread_by_handle (val, inf_obj->inferior);
       if (thread_info != NULL)
-	    {
-	      result = (PyObject *) thread_to_thread_object (thread_info);
-	      if (result != NULL)
-		Py_INCREF (result);
-	    }
+	result = thread_to_thread_object (thread_info);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
       GDB_PY_HANDLE_EXCEPTION (except);
     }
   END_CATCH
-    }
 
-  return result;
+  if (result == NULL)
+    result = gdbpy_ref<>::new_reference (Py_None);
+
+  return result.release ();
 }
 
 /* Implement repr() for gdb.Inferior.  */

gdb/python/py-infthread.c

@@ -284,15 +284,7 @@ PyObject *
 gdbpy_selected_thread (PyObject *self, PyObject *args)
 {
   if (inferior_ptid != null_ptid)
-    {
-      PyObject *thread_obj
-	= (PyObject *) thread_to_thread_object (inferior_thread ());
-      if (thread_obj != NULL)
-	{
-	  Py_INCREF (thread_obj);
-	  return thread_obj;
-	}
-    }
+    return thread_to_thread_object (inferior_thread ()).release ();
 
   Py_RETURN_NONE;
 }

gdb/python/py-stopevent.c

@@ -23,8 +23,8 @@
 gdbpy_ref<>
 create_stop_event_object (PyTypeObject *py_type)
 {
-  return create_thread_event_object (py_type,
-				     py_get_event_thread (inferior_ptid));
+  gdbpy_ref<> thread = py_get_event_thread (inferior_ptid);
+  return create_thread_event_object (py_type, thread.get ());
 }
 
 /* Callback observers when a stop event occurs.  This function will create a

gdb/python/py-threadevent.c

@@ -22,19 +22,19 @@
 
 /* See py-event.h.  */
 
-PyObject *
+gdbpy_ref<>
 py_get_event_thread (ptid_t ptid)
 {
-  PyObject *pythread = nullptr;
+  gdbpy_ref<> pythread;
 
   if (non_stop)
     {
       thread_info *thread = find_thread_ptid (ptid);
       if (thread != nullptr)
-	pythread = (PyObject *) thread_to_thread_object (thread);
+	pythread = thread_to_thread_object (thread);
     }
   else
-    pythread = Py_None;
+    pythread = gdbpy_ref<>::new_reference (Py_None);
 
   if (pythread == nullptr)
     {

gdb/python/python-internal.h

@@ -532,8 +532,7 @@ PyObject *gdbpy_lookup_objfile (PyObject *self, PyObject *args, PyObject *kw);
 PyObject *gdbarch_to_arch_object (struct gdbarch *gdbarch);
 
 thread_object *create_thread_object (struct thread_info *tp);
-thread_object *thread_to_thread_object (thread_info *thr)
-  CPYCHECKER_RETURNS_BORROWED_REF;
+gdbpy_ref<> thread_to_thread_object (thread_info *thr);;
 inferior_object *inferior_to_inferior_object (inferior *inf);
 
 const struct block *block_object_to_block (PyObject *obj);