[Bug 31308] New: po sometimes prints blank instead of object

Bug ID 31308
Summary po sometimes prints blank instead of object
Product lldb
Version 3.6
Hardware Macintosh
OS MacOS X
Status NEW
Severity normal
Priority P
Component All Bugs
Assignee lldb-dev@lists.llvm.org
Reporter mth@xmission.com
CC llvm-bugs@lists.llvm.org
Classification Unclassified

My debug environment is Xcode 8.1 stopped at a breakpoint while debugging an
iOS application (usually 9.3.5 or 10.1) written in Objective C.  Sometimes when
I use po to print an object, all it prints is a blank line. Printing with
different syntax will sometimes make it work.  In this particular example the
object was a property of the argument to a simple method:

- (void)handleDataModelChange: (NSNotification *)nt
{
    NSSet *updatedObjects = [[nt userInfo] objectForKey: NSUpdatedObjectsKey];
    ...
}

The breakpoint was set near the end of the method.  Here is the output of some
po commands I tried.  The last po command prints the object as it should be
printed by the first two po commands.  Instead they just give blank lines.

(lldb) po nt.object

(lldb) po [nt object]

(lldb) po [nt.object class]
NSManagedObjectContext

(lldb) po (NSManagedObject *)nt.object
<NSManagedObjectContext: 0x14576d20>: defaultMainQueueContext

[lldb --version prints lldb-360.1.65]