>
> Interesting...I've never had to do that myself; apparently, they fixed
> this limitation in versions of GNU/Linux from the last several years.
>
I wonder how they fixed it. Maybe a hack somewhere else.
There seems to be a problem with shared Fortran libraries as well.
For a shared slatec lib I get about six undefined references just
linking a trivial Fortran program.
> (GNU R defines MAIN_, MAIN__, and __main. Are there any other
> possibilities?)
>
I haven't noticed any others.
> Sigh...it looks like we'll need to deal with this; even if we can get
> around the problem with a flag on NetBSD, it sounds like there are more
> systems out there than we'll have hacks for. This means a new autoconf
> test, e.g. AC_F77_MAIN_DECLARE or the like. I'll volunteer to write it,
> but how should it work?
>
> I suppose it could define a CPP macro F77_MAIN_DECLARE that either expands
> to nothing or expands to a dummy MAIN_, or whatever, depending upon the
> outcome of the test. The manual would tell users to put this somewhere in
> their program if they want to link to Fortran code.
>
That looks like the best workaround. BTW, there is the -u flag which
I also mentioned to Patrick Welche.
gcc -u MAIN__ main.o foobar.o -o prog -lg2c -lm
The problem with using that is if you use g77 or an f2c driver script
for the linking phase it probably won't have a -u option (g77 doesn't).
That's why I recommended the other approach. You'll still need
a MAIN__ in the program anyway after the configuration process.
> One question is how to handle C++, which should really put extern "C" {...}
> around the declaration. The ideal way to do that would be to bracket this
> with #ifdef __cplusplus ... #endif, but I can't think of a way to do that
> in a macro body. Or, we could put the #ifdef in config.h, but that would
> violate the usual autoconf rules. I guess it wouldn't be such a big deal
> for the manual to say that C++ users should write extern "C" {
> F77_MAIN_DECLARE }.
>
That's the way Tela does it: extern "C" { int MAIN__;}.
> Another question: is it sufficient to compile a dummy Fortran file (a
> foobar subroutine), and link it with a dummy C program (an empty main(),
> plus the MAIN__ or whatever)? Or does the C program have to actually call
> the Fortran routine for the error to occur? I suspect not, but if so the
> AC_F77_MAIN_DECLARE test will have to be intermingled with the F77
> name-mangling detection. Ugh.
>
Even if the Fortran routine isn't called from the C program the problem
remains at least with gcc/g77.
> > You'll probably be saddened to hear that I added something similar to
> > the configure for your FFTW library in the NetBSD Packages Collection.
>
> Shame on you for not sending a bug report!
>
Offtopic suggestion: please add libtool support to libctl for building
shared libraries.
Jason
