[Bug fortran/39178] New: Generate main() rather than using a main in libgfortran/fmain.c

[burnus at gcc dot gnu dot org]

Topic brought up on #gfortran by Janne.

There are some potential issues in using main.c in a library; thus one should
have only link a "main()" if the *.o files don't have a "main".

See also:
http://groups.google.com/group/comp.os.linux.development.apps/browse_thread/thread/e35b2224a7dc27bf/
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/7d483c59db0bb6f/


The solution of SUN is to generate for PROGRAM not only a "MAIN_" but also a
main() which does the initialization and calls then MAIN_. ("MAIN_" should be
present for backward compatibility.)

I think we could do likewise, especially as the code is rather short
(libgfortran/fmain.c):

main (int argc, char *argv[]) {
  store_exe_path (argv[0]);
  set_args (argc, argv);
  MAIN__ (); /* The Fortran PROGRAM */
  return 0;
}

Intel's solution is to link "for_main-o", but that is not as elegant as for
"ifort *.o" one needs to specify "-nofor-main" if there is a non-fortran C
library.

 * * *

Independent of all, I think one should document the gfortran_init() functions
to make the full library functions available even if the "main()" program is
written in C. Besides
  store_exe_path (argv[0]);
  set_args (argc, argv);
(which should be combined to one function) one also has
  _gfortran_set_options()

 * * *

Marked as depending on the array descriptor stuff as with the ABI break one can
get also rid of fmain.c's main(). It might also help with -fwhole-program (cf.
PR fortran/26682) as a "main()" shouldn't be optimized away ;-)


-- 
           Summary: Generate main() rather than using a main in
                    libgfortran/fmain.c
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org
 BugsThisDependsOn: 36825


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39178