Create a special "destroyed" type rather than using null

When a QPDF is destroyed, changing indirect objects to direct nulls
makes them effectively disappear silently when they sneak into other
places. Instead, we should treat this as an error. Adding a destroyed
object type makes this possible.

1 files changed, 5 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 71f241d3..751b1aed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2022-09-08  Jay Berkenbilt  <ejb@ql.org>
+
+        * Add QPDFObjectHandle::isDestroyed() to test whether an indirect
+        object was from a QPDF that has been destroyed.
+
 2022-09-07  Jay Berkenbilt  <ejb@ql.org>
 
         * Add QPDFObjectHandle::getQPDF(), which returns a reference, as