Re: accesibility level problem

[steve quinlan <steven.quinlan@lmco.com>]

My version of GNAT (3.11b) gives a different message :

 Non-local pointer cannot point to local object

 I think this is just standard accessibility rules. The type channelp is
defined at a package level, the object you are aliasing is defined locally
in a subprogram. It has a deeper level than the acces type -- it could go
out of scope, but objects of that access type could still be in scope, and
you could possibly assign the address of the object to a value of the access
type, thus creating the problem of an invalid reference. The accessibility
rules prevent even the possibility of this happening by not allowing
conversion of an access-to-object to a pointer-to-object when the pointer
may outlive the object (I think). So, it's an appropriate case for
unchecked_access.

You'd just want to make sure that in AwaitChannels, you don't save any of
those references in, say, some package body state variable. That could
generate the invalid reference problem.