Re: Fortran 9x support

[Sander Niemeijer]

Hi,

I can understand keeping F77/FFLAGS/FLIBS/AC_PROG_F77 for backwards 
compatibility.
However, the current approach is to keep using these macros and 
variables for f77 and use the new FC* ones only for f90 and upwards. My 
question is whether it is not possible to also include f77 in the FC 
approach?

If so, this might open up a different way to go forward:
 - Only allow the user to use either AC_PROG_F77 or AC_PROG_FC (the old 
or the new way of doing fortran).
 - Use FFLAGS and FLIBS for both F77 and FC. This would make the FC 
approach compatible with GNU make which uses the FC/FFLAGS combination 
for compiling fortran. The fact that we only allow F77 or FC will 
prevent conflicts with these variables.
 - After some time the F77 macro/variable set might be phased out in 
favor of using the FC approach to do f77 compilation.

Just my 2c.

Regards,
Sander

On vrijdag, okt 3, 2003, at 20:12 Europe/Amsterdam, Steven G. Johnson 
wrote:

> Dear Automake folks,
>
> Recently, we've committed a set of patches to autoconf CVS to support
> newer revisions to the Fortran language standard.  The current plan is 
> to
> not document these (yet) in the next autoconf release, but it might be 
> a
> good idea to start thinking about how to support these in automake,
> especially if revisions to the autoconf macros are required.
>
> I've attached a draft of the documentation for the new macros.  The 
> basic
> idea is to divide Fortran support into two categories: legacy Fortran 
> 77,
> and modern Fortran:
>
> * For legacy F77 code, there are the current AC_PROG_F77 etc. macros to
> find $F77, $FFLAGS, $FLIBS, and so on.
>
> * For newer Fortran dialects, the idea is to treat them more like C and
> C++, in that we don't attempt to have separate macros and variables for
> separate language versions going forward.  Instead, there are a new 
> set of
> macros AC_PROG_FC, etcetera (just like the F77 macros with s/F77/FC/) 
> to
> find output variables $FC, $FCFLAGS, $FCLIBS, etcetera.
>
> Basically, automake should just compile .f90, .f95, etcetera files with
> these new output variables.  There is one additional twist: some 
> Fortran
> compilers (xlf, ifc) expect all source files to end with .f, and 
> require a
> special flag for other extensions (even "standard" ones like .f90).  
> So,
> there is a new autoconf macro AC_FC_SRCEXT to figure out how to do
> this.  For each source-file extension required, the user should call 
> it,
> e.g.:
>
> AC_FC_SRCEXT(f90)
> AC_FC_SRCEXT(f95)
> ...
>
> This defines output variables $FCFLAGS_f90, $FCFLAGS_f95, ... that you 
> can
> use to compile .f90 and .f95 files.  Due to compiler quirks, however,
> these flags must appear immediately before the source file to be 
> compiled
> (and only one source file can be compiled at a time).  For example, you
> might do:
>
> foo.o: foo.f90
>      $(FC) -c $(FCFLAGS) $(FCFLAGS_f90) foo.f90
>
> Cordially,
> Steven G. Johnson
> <fortran.doc>