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ACX_F77_CMAIN_FFLAGS([ACTION-IF-SUCCEED], [ACTION-IF-FAIL])
1.1 (2003/04/16) 0.5.57 : Miscellaneous
Steven G. Johnson <stevenj@alum.mit.edu>
This macro figures out if extra Fortran compiler flags are required in order to use the Fortran linker to link programs where the main() function is defined via C (or other language). On some systems, notably the Alpha with Compaq compilers, the Fortran libraries have their own main() function which must be disabled.
Runs ACTION-IF-SUCCEED if successful, and ACTION-IF-FAIL if not. Defines the output variable F77_CMAIN_FFLAGS to any discovered flags. (If ACTION-IF-FAIL is not specified, defaults to halting with an error.)
This macro is especially useful in conjunction with automake, since by default automake uses $F77 to link programs mixing C and Fortran, leading to a link error on some systems. In this case, you should set the FFLAGS for that program to include F77_CMAIN_FFLAGS.
AC_DEFUN([ACX_F77_CMAIN_FFLAGS],
[AC_CACHE_CHECK([for f77 flags to use C main function], acx_cv_f77_cmain_fflags,
[acx_cv_f77_cmain_fflags="unknown"
AC_LANG_PUSH(C)
AC_COMPILE_IFELSE([[int main(void) { return 0; }]],
[mv conftest.$ac_objext conftest_cmain.$ac_objext],
[acx_cv_f77_cmain_fflags=error])
AC_LANG_POP(C)
if test "x$acx_cv_f77_cmain_fflags" != xerror; then
AC_LANG_PUSH(Fortran 77)
acx_save_LIBS=$LIBS
LIBS="conftest_cmain.$ac_objext $LIBS"
acx_save_FFLAGS=$FFLAGS
for acx_flag in none -nofor_main; do
case $acx_flag in
none) FFLAGS=$acx_save_FFLAGS ;;
*) FFLAGS="$acx_save_FFLAGS $acx_flag" ;;
esac
AC_LINK_IFELSE([
subroutine foobar()
return
end
], [acx_cv_f77_cmain_fflags=$acx_flag; break]);
done
FFLAGS=$acx_save_FFLAGS
LIBS=$acx_save_LIBS
AC_LANG_POP(Fortran 77)
fi])
case $acx_cv_f77_cmain_fflags in
error|unknown)
F77_CMAIN_FFLAGS=""
ifelse([$2],,[AC_MSG_ERROR([cannot link C main with Fortran])],[$2])
;;
*)
if test "x$acx_cv_f77_cmain_fflags" = xnone; then
F77_CMAIN_FFLAGS=""
else
F77_CMAIN_FFLAGS="$acx_cv_f77_cmain_fflags"
fi
$1
;;
esac
AC_SUBST(F77_CMAIN_FFLAGS)
])