Re: Combining GNU C++ and Intel Fortran

[Noah Misch]

On Fri, Jun 24, 2005 at 08:30:51AM +0200, Arjen Markus wrote:
> Noah Misch wrote:

> > > Noah Misch wrote:
> > > > Yes; redefine FCLIBS.

> > I suggest defining it before you call any Fortran-related macros.  
> > Nonetheless,
> > the choice of position does not matter to the macros currently in Autoconf.
> > 
> 
> Interesting. Is there documentation about the cooperation and possible
> conflicts
> between the predefined macros?

Note that FCLIBS is a shell variable, not a macro.  The Autoconf manual realizes
some of the documentation you describe, but I doubt the treatment is complete.

Autoconf macro calls, like `AC_PROG_FC', in `configure.ac' expand to some text,
typically shell commands, in `configure'.  Many of these groups of commands can
set certain shell variables; the documentation for the macro usually names them.
For example, AC_PROG_CC can set CC and CFLAGS.

If a variable holds the name by which to call a tool or the flags to pass to
every invocation of that tool, Autoconf macros (should) only modify if it is
unset or empty.  The GNU Coding Standards inspire[1] this behavior.  FCLIBS
receives the same treatment.  Autoconf macros do unconditionally overwrite some
variables, usually ones you would not see in the absence of Autoconf, like
`interpval' and `GETLOADAVG_LIBS'.

You can always change a shell variable after the commands that set it run.  When
the commands respect an existing value, as they do for FCLIBS, I recommend
setting the value before you call macros that use or (would) set it.  That way,
any use _of_ the variable in those macros will take your value.

> > _AC_FC_LIBRARY_LDFLAGS in lib/autoconf/fortran.m4 is the macro that deals 
> > with
> > FCLIBS.
> 
> Okay, thank you for this information. I looked at this file (for
> autoconf 2.59)
> and saw that the Intel fortran compiler is called "ifc". The official
> name
> for it nowadays is "ifort".

CVS Autoconf is aware of that.

[1] http://www.gnu.org/prep/standards/html_node/Command-Variables.html