Re: Possible compiler bug with this simple program

[Jerry <lanceboyle@qwest.net>]

On Aug 29, 6:00 pm, "Randy Brukardt" <ra...@rrsoftware.com> wrote:
> "Jerry" <lancebo...@qwest.net> wrote in message
>
> news:97b1150b-cb8f-4972-b594-2ae59af84147@x16g2000prn.googlegroups.com...
> ...
>
> >FWIW, in the _real_ application that I am working on, plmap is written
> >in C (and accessed from my binding by an Import).
>
> Interestingly, that's completely different. That *should* work on all Ada
> compilers (note that the wording specifically excludes unconstrained
> parameters for pragma Import).
>
> This example program is unportable garbage, unfortunately, because of
> AI05-0002-1, and also because of  B.1(38.1/2) (the "buyer beware" clause:
> there is no requirement that an Ada program actually work as expected if you
> force its conventions to another language (like C).
>
> Admittedly, this is a bit strange. In this case, C works fine as the
> receiver of such a call because it has no need to know the bounds of the
> array passed. (And if it does, they're going to be passed explicitly.) But
> Ada does need to know those bounds, and you can't even pass them explicitly
> because the Ada compiler will have to assume something for the lower bound
> in order to generate indexing operations (and that may be different than
> what you intended).
>
> The net effect is that the example program doesn't prove anything useful. It
> would need to import an actual C subprogram in order to be a useful test.
>
>                                          Randy.

OK--this clears things up for me. And possibly validates the reason I
wrote the _real_ application the way that I did, thinking that C
arrays always starts from 0  so passing the length along as a separate
parameter should work.

But it looks like in testing (and posting) an all-Ada example I
muddied the situation--or worse--used a completely different example
from what my original code was.

I'll see if I can make another example where plmap is a simple program
in C that is Import-ed and see if it bombs on a 64-bit computer.

Jerry