From: Steve Kargl <sgk@troutmask.apl.washington.edu>
To: Dave Love <dave.love@manchester.ac.uk>
Cc: fortran@gcc.gnu.org
Subject: Re: backwards incompatibility
Date: Mon, 12 Mar 2018 17:05:00 -0000 [thread overview]
Message-ID: <20180312170458.GA61632@troutmask.apl.washington.edu> (raw)
In-Reply-To: <871sgp8fpb.fsf@albion.it.manchester.ac.uk>
On Mon, Mar 12, 2018 at 03:40:48PM +0000, Dave Love wrote:
> It's quite a pain for supporting research systems that the gfortran
> module format changes incompatibly with every (?) new version. For
> instance, you can't mix development packages built with the RHEL system
> compiler with the more recent "devtoolset" compiler needed for hardware
> support. As far as I know, the proprietary compilers don't have the
> same issue. I can't find anything written about that, but I haven't
> tried to understand the implementation. Is there something written?
> Otherwise, is it feasible to convert older module files to newer
> formats, given that the ABI doesn't change, as I've seen in release
> notes (and would hope)? If so, where would one look in the code to see
> about doing so?
>
> Version 8 makes the situation worse by breaking run time compatibility,
> not just build-time, with a different libgfortran shared library
> version. That already caused considerable disruption with Fedora
> packaging after the switch to GCC 8. With ELF, can't you use versioned
> symbols to avoid a new soname, like libgcc and libgomp do?
>
> Regardless of any annoyances, thanks for keeping a competitive free
> compiler going!
Hi Dave,
While I do not speak for the other contributors, I can
assure you that we take breaking the library ABI quite
serious. We maintain a list of changes that we know will
cause problems. If a change occurs that breaks the ABI,
we try to merge as many changes from the list as possible
to minimize on-going breakage. See
https://gcc.gnu.org/wiki/LibgfortranAbiCleanup
for those that have yet to be merged/fixed. Unfortunately,
the addition of user defined derived type IO, which was a
much requested feature, required a change to the library
internals for the upcoming 8.0.
Maintaining the internals of *.mod files is even more difficult
as changes are sometimes required for bug fixes as well as when
new features are implemented (e.g., parameterized derived type).
--
Steve
next prev parent reply other threads:[~2018-03-12 17:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-12 15:40 Dave Love
2018-03-12 17:05 ` Steve Kargl [this message]
2018-03-12 20:42 ` Dave Love
2018-03-12 21:18 ` Thomas Koenig
2018-03-13 15:14 ` Dave Love
2018-03-14 2:31 ` Jerry DeLisle
2018-03-16 13:48 ` Dave Love
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