Re: Generic Actual Tagged Objects Not Implicitly Aliased?

[stt@houdini.camb.inmet.com (Tucker Taft)]

Matthew Heaney (matthew_heaney@acm.org) wrote:

: Suppose we have the following tagged type:

: type T is tagged limited ...;

: ...
: Now, suppose I have a generic declaration

: generic
:    O : in out T;
: package GP is ...;

: package body GP is

:    .... O'Access ...


: package Objects is

:    O : T;

: end;

: with Objects;
: package P is new GP (O);

: My compiler (GNAT 3.10p) is telling me that that instantiation of P is
: illegal, becuase O is not declared as aliased.

This sounds like a bug in GNAT.

: ...
: This behavior begs certain questions:

: 1) Why can't you take the 'Access of generic formal object of a tagged
: type, without the actual object being declared as aliased?  This would make
: the behavior consistant with that for subprogram parameters.

You can.  Don't confuse bugs in an implementation with bugs
in the language definition ;-).

: ...
: Thanks,
: Matt

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA