Re: Incomplete types used with generics

["Randy Brukardt" <randy@rrsoftware.com>]

"Jeremiah" <jeremiah.breeden@gmail.com> wrote in message 
news:830c0323-a06c-4884-9214-89f3ee6f17b5@googlegroups.com...
> One of the things I read about with ada2012 is the ability to use 
> incomplete types
> as generic parameters. However, I am having some trouble implementing 
> them.

...
> What am I missing?

You missed at least 6 months of wrestling with various AdaCore people about 
this feature, specifically over some proposed ACATS tests. (Most of the 
tests showed lovely GNAT bug boxes.) They were trying very hard to find 
reasons that the tests were illegal, because there was an problem with the 
design of their implementation that made the tests very hard to implement. 
They managed to uncover some language problems that will probably be fixed 
someday, but in particular, everyone eventually agreed that the test using 
limited with (CC51010) is correct (now). I've heard that they've fixed the 
compiler so that test works, so you'll probably be able to get that to work 
at some future point (but surely not with GNAT GPL 2014, which clearly 
predates the fixes).

I suspect that you ran afoul of the fact that the freezing rules differ for 
tagged incomplete vs. untagged incomplete types, but even if you fixed that 
you'd still be very likely to run into problems with current GNAT versions 
unless you are a GNAT PRO user and can get a wavefront.

I'd suggest trying this again next year.

                                Randy.