[Bug fortran/56226] New: Add support for DEC UNION and MAP extensions

[Bug fortran/56226] New: Add support for DEC UNION and MAP extensions

[russelljbrennan at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

             Bug #: 56226
           Summary: Add support for DEC UNION and MAP extensions
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: russelljbrennan@gmail.com


Porting old f77 code for use with gfortran is fairly straightforward, even for
most extensions.  The UNION and MAP extensions thusfar prove impossible to port
without modifying the UDT interface.  Existing compilers can candle these
extensions (intel ifort and portland group) but there is no open source
alternative available afaik.  UNIONs and MAPs are widely lamented exclusions of
the later fortran standards.  Addition of support for these extensions would
facilitate automated conversion of much existing code to gfortran-compatible
code.

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |burnus at gcc dot gnu.org

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2013-02-06 17:42:04 UTC ---
I don't think that the implementation of UNION/MAP will happen soon, given that
it is not a simple feature and most effort concentrates on supporting the
Fortran standard. However, if someone volunteers to work on this, it might
happen sooner.

For documentation, see:
-
http://publib.boulder.ibm.com/infocenter/comphelp/v101v121/topic/com.ibm.xlf121.aix.doc/language_ref/unionmap.html
-
http://software.intel.com/sites/products/documentation/doclib/stdxe/2013/composerxe/compiler/fortran-mac/GUID-1CC04793-AF79-4E0F-AC78-DD4CF985C23F.htm

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[russelljbrennan at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

--- Comment #2 from russelljbrennan at gmail dot com 2013-02-07 13:31:16 UTC ---
It seems to me that the UNION/MAP pair is analogous to a basic form of a c/c++
union of structs.  Could the corresponding code not be ganked and fitted to
this application?  I did notice in the IBM link that you provided that unions
are only defined in an enclosing record structure... RECORDs and STRUCTUREs are
easily replace with UDTs.  It would make sense to me to allow UNION/MAP inside
UDTs as well as RECORDs and STRUCTUREs.

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> 2013-02-08 00:46:19 UTC ---
Union can be replaced with EQUIVALENCE I think.

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[russelljbrennan at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

--- Comment #4 from russelljbrennan at gmail dot com 2013-02-08 01:03:12 UTC ---
>From a memory standpoint yes, union/map can be replaced by equivalence.  From
an API standpoint it cannot afaik.  A suggestion for the former lies here
http://stackoverflow.com/questions/14733238/convert-fortran-dec-union-map-extensions-to-anything-else

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
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                 CC|                            |janus at gcc dot gnu.org

--- Comment #5 from janus at gcc dot gnu.org 2013-02-08 13:00:54 UTC ---
(In reply to comment #2)
> It seems to me that the UNION/MAP pair is analogous to a basic form of a c/c++
> union of structs.  Could the corresponding code not be ganked and fitted to
> this application?

Since GCC is a "C-centered" compiler, so to speak, the middle end is surely
able to handle unions (if the Fortran front end is taught to support them).


> It would make sense to me to allow UNION/MAP inside UDTs

Yes! (if by UDTs you mean "derived types", DT, as they are called in the
Fortran standard)


> as well as RECORDs and STRUCTUREs.

No. I would say the STRUCTURE/RECORD syntax should not be used at all, since it
can be replaced by standard DTs.


IMHO, UNION/MAP would be a useful extension to standard Fortran, while
STRUCTURE/RECORD would not (and should not be implemented in gfortran).

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
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             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2014-12-09
                 CC|                            |fritzoreese at gmail dot com
     Ever confirmed|0                           |1

--- Comment #6 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
The discussion has started at
https://gcc.gnu.org/ml/fortran/2013-02/msg00079.html and died at
https://gcc.gnu.org/ml/fortran/2013-03/msg00048.html.

Fritz Reese has offered to implement DEC Extensions at
https://gcc.gnu.org/ml/fortran/2014-09/msg00255.html, but the thread died at
https://gcc.gnu.org/ml/fortran/2014-10/msg00081.html.

IMO f77 extensions should be frozen: bugs being documented and not fixed,
extension
requests put under 6.2 Extensions not implemented in GNU Fortran.

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[fritzoreese at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

--- Comment #7 from Fritz Reese <fritzoreese at gmail dot com> ---
FWIW I have the patches ready against the gcc-5.0.0 dev trunk, I'm just waiting
on my employer's lawyer, who has been on vacation for several weeks, to sort
out the legal issues.

The wheels of justice spin awfully slow.

[Bug fortran/56226] Add support for DEC UNION and MAP extensions

[joel.matz at horizonbtc dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56226

Joel Matz <joel.matz at horizonbtc dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |joel.matz at horizonbtc dot com

--- Comment #8 from Joel Matz <joel.matz at horizonbtc dot com> ---
Any word on this?  I would certainly be willing to help test.