Compatibility gfortran 4.4 -> 4.5?

[Steve Kargl]

On Sat, Sep 18, 2010 at 02:08:21AM +0200, Gerald Pfeifer wrote:
> I recall that when changing the default Fortran compiler on FreeBSD
> from 4.3 to 4.4 (and I believe 4.2 to 4.3) some things broke due to
> some binary incompatiblities, unlike C where this works just fine.

You're probably recalling the change from a 64-bit int
record marker to 32-bit record marker and Intel's scheme
for records that are larger than 2 GB.  That change occurred
in 4.2.

> Now, going from 4.4 to 4.5, is this an issue again or should one be
> able to use libraries originally compiled with the older version together
> with others and in programs compiled with the later version?

4.4 and 4.5 should be compatible.

> That would be a good addition to the GCC 4.5 release note, I think, and
> similar for GCC 4.6 when that comes out?  I'll be happy to take care of
> that if you guys provide me guidance/input.

The jury is still out on compatibility for 4.6.  If the array
descriptor rewrite is completed, then the library ABI will 
be broken.  At the point, we have a long list of other 
library changes to make.  See http://gcc.gnu.org/wiki/LibgfortranAbiCleanup/

-- 
Steve