Annotate nullable argument

The `this_` argument is passed to `gtk_expression_watch()`, which
accepts it as nullable.

Fixes: #2900

diff --git a/gtk/gtkexpression.c b/gtk/gtkexpression.c
index d690487ca882f438c244b4491699a2a21137f810..750ee2c57c86e4ff4ebc196315fb5662051f2a70 100644 (file)
--- a/gtk/gtkexpression.c
+++ b/gtk/gtkexpression.c
@@ -1961,7 +1961,7 @@ gtk_expression_bind_notify (gpointer data)
  * @self: (transfer full): a #GtkExpression
  * @target: (transfer none) (type GObject): the target object to bind to
  * @property: name of the property on @target to bind to
- * @this_: (transfer none) (type GObject): the this argument for
+ * @this_: (transfer none) (type GObject) (nullable): the this argument for
  *     the evaluation of @self
  *
  * Bind @target's property named @property to @self.