Re: Ada Address = C pointer ?

[tmoran@acm.org]

> >   Ada                   C
> >   -----------------------
> >   Address          void *
> >   Address          char *
> >   Null_Address       NULL
> >
>
> In general - compiler specific. Having said that, I'm not aware of any
> implementations where that kind of relationship is not true.
  ARM 13.7(37) gives the implementation advice that "Address should be
of a private type."  So it most assuredly is not guaranteed to be anything
at all.  In Ada compilers allowing segment+offset addressing modes
on Intel CPUs, for instance, System.Address will be 48 bits wide, whereas
a C pointer is probably 32 bits with segment implied.  Use access types,
not System.Address.

> > If they are of the language, where on the ARM it says so?
>
> Actually, I suggest a review of Annex B, section 3 (or B.3). For example,
> at the end of B.3, the Implementation Advice describes the interface
> correspondence that SHOULD (not must) be implemented. I believe GNAT
> follows the implementation advice in this area. I would expect most other
> vendors to do the same.
  B.3(67 .. 71) refer to Ada access types, not to System.Address, and
to parameter passing, where of course the compiler may well do some
implicit conversions.