C/Fortran glue code

[Peter Eisentraut]

Autoconf inserts this code into C program to allow linking against Fortran
libraries:

#ifdef F77_DUMMY_MAIN
#  ifdef __cplusplus
     extern "C"
#  endif
   int F77_DUMMY_MAIN() { return 1; }
#endif

However, this isn't necessary if the user never called AC_F77_DUMMY_MAIN.
Therefore I suggest that this code be omitted in that case, so the
configure script is shorter and config.log is easier to read.

I have found the following ChangeLog entry which appears to have had the
same idea, but in fact it doesn't do what it says --
_AC_LANG_PROGRAM_C_F77_HOOKS isn't used anywhere.

2001-07-18  Akim Demaille  <address@hidden>

        The C-Fortran 77 hooks are available only once AC_F77_DUMMY_MAIN
        was run, while they are needed also when it is expanded.
        Reported by Nicolas Joly.

        * aclang.m4 (AC_F77_DUMMY_MAIN): Define _AC_LANG_PROGRAM_C_F77_HOOKS.
        (AC_LANG_PROGRAM(C)): Use it instead of depending upon
        AC_F77_DUMMY_MAIN being expanded.

Thus, I propose the attached patch.

-- 
Peter Eisentraut   address@hidden

patch
Description: Patch