Add a note about what happens when passing 0 to qobject_cast in the doc

Reviewed-by: Kavindra Palaraja

1 files changed, 2 insertions, 1 deletions

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 7e5f77949a..6583b85d5e 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -912,7 +912,8 @@ QObject::~QObject()
     \relates QObject
 
     Returns the given \a object cast to type T if the object is of type
-    T (or of a subclass); otherwise returns 0.
+    T (or of a subclass); otherwise returns 0.  If \a object is 0 then 
+    it will also return 0.
 
     The class T must inherit (directly or indirectly) QObject and be
     declared with the \l Q_OBJECT macro.