gcancellable: Mention nullability in g_cancellable_cancel() docs
Calling g_cancellable_cancel(NULL) is an explicitly allowed no-op, for
convenience. Document and annotate that.
diff --git a/gio/gcancellable.c b/gio/gcancellable.c
index 800e8f3..a089a82 100644
--- a/gio/gcancellable.c
+++ b/gio/gcancellable.c
@@ -458,7 +458,7 @@
/**
* g_cancellable_cancel:
- * @cancellable: a #GCancellable object.
+ * @cancellable: (nullable): a #GCancellable object.
*
* Will set @cancellable to cancelled, and will emit the
* #GCancellable::cancelled signal. (However, see the warning about
@@ -469,7 +469,9 @@
* it from a thread other than the one running the operation that was
* passed the @cancellable.
*
- * The convention within gio is that cancelling an asynchronous
+ * If @cancellable is %NULL, this function returns immediately for convenience.
+ *
+ * The convention within GIO is that cancelling an asynchronous
* operation causes it to complete asynchronously. That is, if you
* cancel the operation from the same thread in which it is running,
* then the operation's #GAsyncReadyCallback will not be invoked until
