If I cancel cc and type ~ cc does not kick in and if I force it with Ctrl+Space, it does not show me the correct choice
in this case it shows only tokens from the global namespace, nneither the constructor or destructor nor the class itself.
So it seems the tilde is not recognized correctly (after it is typed).
The token itself is known, because cc kicks in correctly after the second colon and shows Abc and ~Abc.
If cc is not cancelled after typing the colon and you type the tilde (~), the selection in the cc-box jumps correctly to ~Abc, but if you now hit enter it comes to the error described by Folco.
I think it's the same cause for both issues.