Re: Defining a HAVE_J0 in config.h for gfortran?

[Tom Tromey <tromey at redhat dot com>]

>>>>> "Steve" == Steve Kargl <sgk@troutmask.apl.washington.edu> writes:

Steve> I'm contemplating adding j0, j0f, j1, j1f, y0, y0f, y1, and y1f
Steve> intrinsic functions to gfortran for compatibility with g77.  In
Steve> gcc/libgfortran I can modify configure.ac with a line similar to
Steve> AC_CHECK_LIB([m],[j0],[AC_DEFINE([HAVE_J0],[1],[libm includes j0])])
Steve> to check that j0 is present in libm.  I however need the HAVE_J0
Steve> symbol in gcc/gcc/fortran.  There is no configure.ac in this 
Steve> directory, so I need some other way to define HAVE_J0.  Any pointers
Steve> would be appreciate.

One problem is that you want to do the library tests for the target,
but front ends are built for the host.  For gcj our solution was to
have the library generate a spec file that is then read by the front
end.  Then we add internal-only options that can be used to
communicate configury (or whatever) results from the library back to
the compiler.  This approach is very flexible, e.g., we could (in
theory, I don't think we've tried this) handle situations where
different multilibs of the same compiler have different
characteristics.

Tom