[sigc] Unexpected behavior when freeing a trackable object from inside a slot

["Andrey H." <ahanins gmail com>]

Hi,

    I noticed that if a trackable object is freed from inside the slot 
which is setup to track this object then the slot is immediately 
invalidated. Problem arises when such a slot holds a lambda which 
captures some other variables by-value or some variables are bound by 
value to the slot. In such cases the invalidation of the slot causes all 
bound object instances to be immediately freed.

    I have attached a test case patch (for the current master) which 
demonstrates the issue using lambda captures and sigc::bind bounds.

    My question: is it a bug or it's supposed to work like that?

    The patch also contains a 3rd test which disconnects the slot 
explicitly from inside the lambda slot with captured variables, but in 
this case it doesn't cause captured variables to be freed right from 
inside the slot. So I'm inclined to think that track_obj should behave 
in a similar safe way.

BR, Andrey

Attachment: free_trackable_from_slot.patch
Description: Text Data