Re: different compilers: different standard types?????

[Ludovic Brenta <ludovic.brenta@insalien.org>]

Marius Amado Alves <maa@liacc.up.pt> writes:

> I have a related problem, at least with GNAT 3.15p, the compiler of
> all us poor academics.
> 
> The standard requires that "the range of Integer should be no wider
> than that of Long_Integer" 3.5.4 (25). (I'm not sure this is an
> intelligent limitation, but never mind.)

Basically, this means that by definition, Long_Integer is at least as
long as Integer.  It's not really a limitation, but a definition of
terms.

> GNAT defines Integer and Long_Integer for 32-bit, and
> Long_Long_Integer for 64-bit.
> 
> So if you want to define an integral type with a greater range than
> (the associated with) 32 bits, you have to use Long_Long_Integer as
> a base. But then you hinder portability, because Long_Long_Integer
> is not standard.
> 
> So I guess my question is: Why does not GNAT define Integer (and
> Long_Integer) for 64-bits? AFAICS the standard does not impose a
> upper limit on Integer.  And don't tell me the answer is: Because
> then Short_Integer would have 32-bits, and that is not what the C
> world calls short.

It's not because of C, it's because in your case, GNAT targets a
32-bit processor.  This means that, if you recompile GNAT to target a
64-bit machine, Integer and Long_Integer should become 64 bits wide.

You may also want to try -gnatdm, debug.adb says this forces
Long_Integer to be 64 bits wide on all targets, but it also warns that
this flag may cause other problems.

-- 
Ludovic Brenta.