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From: Ralf Wildenhues (Ralf.Wildenhues_at_[hidden])
Date: 2006-08-21 03:14:57


Hello Adrian, Jonathan,

* Adrian Knoth wrote on Sat, Aug 19, 2006 at 08:38:15PM CEST:
> On Thu, Aug 17, 2006 at 11:48:44PM +0100, Jonathan Underwood wrote:
>
> > Compiling a file with the gcc options -Wall and -pedantic gives the
> > following warning:
> > mpi.h:147: warning: ISO C90 does not support 'long long'
> > Is this intentional, or is this a bug?
>
> If you do not insist on using C90, you may compile with -std=c99
> to get rid of this message ;)

More precisely, the OpenMPI installation that provides this mpi.h file
was compiled with 'long long' support, which quite undoubtedly is a
feature rather than a bug. Users should not compile their code with
strict C89 settings.

> I don't have the C90 (ANSI-C) at my fingertips, but I confirm it
> does not support "long long".

Yes.

> Perhaps we should use int64_t instead.

No, that would not help: int64_t is C99, so it should not be declared
either in C89 mode. Also, the int64_t is required to have 64 bits, and
could thus theoretically be smaller than 'long long' (no, I don't think
any such systems exist today).

Cheers,
Ralf