Re: Ada array vs C pointer (call by reference)

[Keith Thompson <kst-u@mib.org>]

Maciej Sobczak <see.my.homepage@gmail.com> writes:
> On 28 Cze, 02:56, "Peter C. Chapin" <pcha...@sover.net> wrote:
> > My understanding is that the interfacing to C is only really meaningful
> > if the Ada compiler is in some way associated with a corresponding C
> > compiler (for example, created by the same vendor).
> 
> This is exactly my point.

And it's exactly wrong, or at least overstated.

The only required association is that the provider of the Ada compiler
*knows* the characteristics of the relevant C compiler.  That's not
hard to find out.  I'm not associated with the authors of gcc, but I
can find out its characteristics on a given system in just a few
minutes.  For that matter, I can probably write a program that
produces as output the correct declarations for Interfaces.C.

And since code generated by different C compilers on the same system
has to interoperate, it's generally in the interest of the C compiler
vendors to use the same representations for types on a given system.

Providing both the C and Ada compilers certainly makes it easier to
get Interfaces.C right, but even if the compilers aren't associated,
it's reasonably easy and reasonably reliable (certainly more so than
just assuming that Float and C_Float are compatible).

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
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