Checks if @task's #GCancellable has been cancelled, and if so, sets @task's error accordingly and completes the task (see g_task_return_pointer() for more discussion of exactly what this means).
%TRUE if @task has been cancelled, %FALSE if not
2.36
See Implementation
Checks if @task's #GCancellable has been cancelled, and if so, sets @task's error accordingly and completes the task (see g_task_return_pointer() for more discussion of exactly what this means).