Hi Kris,
I've fixed Rconfig.h.
Cheers, Fons.
On Sat, May 05, 2001 at 06:23:04PM -0400, Kristjan H Gulbrandsen wrote:
> Hi
>
> PHOBOS has been trying to get their software to work with ROOT3.
> While we were able to get it to compile quite a while ago, we found
> problems with streaming old files in. One problem found was that
> byte swapping no longer seemed to be in effect. (We are using
> intel-linux with egcs-1.1.2 release.) Eventually, the problem
> was found to be a combination of a change in RConfig.h between
> ROOT2.25 and ROOT3.00 and a compiler flag that we use. Specifically,
> ROOT2.25's RConfig.h checks for the existence of '__linux', while
> ROOT3.00 checks for the existence of 'linux'. I looked through ROOT's
> changelog and found that the switch was due to an observation that
> only 'linux' is defined by GCC and KCC on all platforms. The problem
> came about, because PHOBOS uses the -ansi flag during compilation.
> Apparently (according to the gcc online documentation), predefined
> macros such as 'unix' or 'linux' are incompatible with the ISO C and
> ISO C++ standards, so the specification of -ansi will make these
> undefined.
>
> This is easily testable by using the following code:
>
> #include <iostream.h>
>
> int main()
> {
> #ifdef linux
> cout << "linux is defined" << endl;
> #else
> cout << "linux is not defined" << endl;
> #endif
> }
>
> and compiling by using just g++ and then by using g++ -ansi and
> seeing what it prints out. I am writing this email to make people
> aware of this issue and to ask if ROOT could do the following
> check in RConfig.h:
>
> #if defined(linux) || defined(__linux__)
> or
> #if defined(linux) || defined(__linux)
> instead of just
> #if defined(linux)
>
> Right now PHOBOS can get around the problem since we detect this
> separately with 'uname -s' (which works for us because we only use systems
> that know this command), and if linux is detected, we give a -Dlinux to
> g++ to define it. In any case, we would prefer if RConfig.h worked
> (untouched by us) independent of the -ansi flag as suggested by the change
> mentioned above.
>
> Thanks,
>
> Kris Gulbrandsen
> gulbrand@mit.edu
>
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