Re: Strange LT_INIT behavior

[Jeff Squyres]

On May 16, 2009, at 12:08 AM, Peter O'Gorman wrote:

> > - Before LT_INIT is invoked, should Open MPI's configure.ac set
> > F77=no if --disable-mpi-f77 is specified, and FC=no if --disable- 
> mpi-
> > f90 is specified?
> > - Or is there another way to tell Libtool "I don't want support for
> > F77 / F90"?
> > - Or is it a bug that LT_INIT is resetting $enable_shared /
> > $enable_static?
> > - Or ...?
>
> I haven't checked, but I'd guess that this is not limited to darwin,
> it seems like a bug to me that on linux with GNU ld, libtool reports
> that /usr/bin/true can create shared libraries.

This is true, even Linux GNU ld reports that /bin/true can make shared  
libraries:

checking for /bin/true option to produce PIC...
checking if /bin/true static flag  works... no
checking if /bin/true supports -c -o file.o... no
checking if /bin/true supports -c -o file.o... (cached) no
checking whether the /bin/true linker (/usr/bin/ld -m elf_x86_64)  
supports shared libraries... yes


> Can you move LT_INIT to come just after AC_PROG_CC, but before
> AC_PROG_CXX, AC_PROG_F77 etc.? If so then doing so should, I think,
> make libtool not check other languages, then checking all the other
> languages conditionally would make the libtool language checks
> conditional too.


Nifty idea!

Unfortunately, it runs into a bit of a snag -- AC_PROG_F77 first  
checks for g77; we have long-since overridden this ordering with our  
own:

ompi_fflags_save="$FFLAGS"
AC_PROG_F77([gfortran g77 f77 xlf frt ifort pgf77 fort77 fl32 af77])
FFLAGS="$ompi_fflags_save"

If I move up LT_INIT to shortly after AC_PROG_CC (but before  
AC_PROG_CXX|F77|F90), then C++ Libtool tests come *after* AC_PROG_CXX,  
but the Libtool tests for F77 seem to come *before* we call  
AC_PROG_F77, and therefore call AC_PROG_F77 with the default ordering;  
not the ordering that we want.

Hence, g77 is found instead of gfortran.  This, unfortunately, is a  
dealbreaker for us.  :-(

Is there another way?

--
Jeff Squyres
Cisco Systems