Re: the _GNU_SOURCE blues

[Phil Edwards <pedwards at disaster dot jaj dot com>]

On Tue, Jun 19, 2001 at 01:35:23PM -0500, Stefan Seefeld wrote:
> > > which is the reason that the spec file defines it for g++ by default.
> > 
> > Not anymore.  This was fixed for the 3.0 release.
> 
> The spec file does indeed not contain the _GNU_SOURCE symbol any more.

Ah, my apologies.  I misunderstood where you were going with your argument.

Yes, on certain systems the C++ compiler will always define this preprocessor
symbol.  (I say "the C++ compiler" because you can use 'gcc' or 'g++'
and the same compiler will fire; see the GCC Manual for more on this.)

As you noted, there was a lot of discussion about this.  Right now, a C++
environment on some systems simply uses more symbols than a C environment
does.  There are other symbols besides _GNU_SOURCE which also get predefined
automatically; _GNU_SOURCE just happens to be more visible.

If a package intends to use the C++ compiler to build its code, then
it should tell autoconf to use the C++ compiler when running its tests.
Doing otherwise would be a bug in that package, just as if I intended to
use the FORTRAN compiler to build my code but used an Ada compiler to test
the system; they are /different/ lanaguages.

Now, if a C compiler and a C++ compiler should be giving the same results
on an autoconf test, but they do not, then that's a different kind of bug.


Phil

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