* Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine
@ 2010-03-30 17:50 Glenn H Sembroski
2010-03-30 23:58 ` Harald Servat
2010-03-31 11:29 ` Axel Freyn
0 siblings, 2 replies; 5+ messages in thread
From: Glenn H Sembroski @ 2010-03-30 17:50 UTC (permalink / raw)
To: gcc-help
Hi,
I have a problem trying to prepare a large simulation package, using
mixed F90 and C++ routines, to compile and build under GCC (g++, and
gfortran). The problem is I have a C++ function: Gauss() which is
called from an F90 routine:
x=gauss()
This package was made able to build under the Intel fortran compiler by
adding to the fortran file the Intel compile directive:
!DEC$ ATTRIBUTES ALIAS:'Gauss' :: gauss
I attempted to build this program using GCC where for F90 code the
gfortran compiler option -fno-underscoring was used.
Presently my fortran routine won't build. It gets the error:
485: undefined reference to `gauss'
So, my question is, is there a way in GCC to enable the linker to find
the C++ 'Gauss' method?
Thanks,
Dr. Glenn Sembroski
Physics Dept.,Purdue University
sembrosk@purdue.edu
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine
2010-03-30 17:50 Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine Glenn H Sembroski
@ 2010-03-30 23:58 ` Harald Servat
2010-03-31 11:33 ` Toon Moene
2010-03-31 11:29 ` Axel Freyn
1 sibling, 1 reply; 5+ messages in thread
From: Harald Servat @ 2010-03-30 23:58 UTC (permalink / raw)
To: Glenn H Sembroski; +Cc: gcc-help
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Hello Glenn,
En/na Glenn H Sembroski ha escrit:
> Hi,
> I have a problem trying to prepare a large simulation package, using
> mixed F90 and C++ routines, to compile and build under GCC (g++, and
> gfortran). The problem is I have a C++ function: Gauss() which is
> called from an F90 routine:
> x=gauss()
>
> This package was made able to build under the Intel fortran compiler by
> adding to the fortran file the Intel compile directive:
>
> !DEC$ ATTRIBUTES ALIAS:'Gauss' :: gauss
>
> I attempted to build this program using GCC where for F90 code the
> gfortran compiler option -fno-underscoring was used.
>
> Presently my fortran routine won't build. It gets the error:
>
> 485: undefined reference to `gauss'
>
> So, my question is, is there a way in GCC to enable the linker to find
> the C++ 'Gauss' method?
I don't know if the linker supports for this directly. But you can try
with the function attribute 'alias("target")' which is documented in
[1]. It creates a new name for the same routine, so you can call it
through the two names (the original, and the aliased).
In your case, you should define in your C++ file an alias to "Gauss"
which is called "gauss".
Besides, IIRC, ICC also supports this function attribute, so you
should be able to apply it transparently.
[1] http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
Regards.
> Thanks,
> Dr. Glenn Sembroski
> Physics Dept.,Purdue University
> sembrosk@purdue.edu
>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine
2010-03-30 23:58 ` Harald Servat
@ 2010-03-31 11:33 ` Toon Moene
2010-03-31 12:51 ` Tobias Burnus
0 siblings, 1 reply; 5+ messages in thread
From: Toon Moene @ 2010-03-31 11:33 UTC (permalink / raw)
To: Harald Servat; +Cc: Glenn H Sembroski, gcc-help, gfortran
[ Copied to the GNU Fortran mailing list - probably a better forum for
this question ]
Harald Servat wrote:
> Hello Glenn,
>> I have a problem trying to prepare a large simulation package, using
>> mixed F90 and C++ routines, to compile and build under GCC (g++, and
>> gfortran). The problem is I have a C++ function: Gauss() which is
>> called from an F90 routine:
>> x=gauss()
>>
>> This package was made able to build under the Intel fortran compiler by
>> adding to the fortran file the Intel compile directive:
>>
>> !DEC$ ATTRIBUTES ALIAS:'Gauss' :: gauss
>>
>> I attempted to build this program using GCC where for F90 code the
>> gfortran compiler option -fno-underscoring was used.
>>
>> Presently my fortran routine won't build. It gets the error:
>>
>> 485: undefined reference to `gauss'
>>
>> So, my question is, is there a way in GCC to enable the linker to find
>> the C++ 'Gauss' method?
>
> I don't know if the linker supports for this directly. But you can try
> with the function attribute 'alias("target")' which is documented in
> [1]. It creates a new name for the same routine, so you can call it
> through the two names (the original, and the aliased).
> In your case, you should define in your C++ file an alias to "Gauss"
> which is called "gauss".
>
> Besides, IIRC, ICC also supports this function attribute, so you
> should be able to apply it transparently.
>
> [1] http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
The Standard (as of Fortran 2003, supported by GNU Fortran and ifort)
way to do this is to add the following to your Fortran code:
$ cat a.f90
interface gauss
function gauss() bind(c, name="Gauss")
use, intrinsic :: iso_c_binding
real(c_float) :: gauss
end function gauss
end interface gauss
x = gauss()
end
$ gfortran -c a.f90
# The command 'nm' will show you that the right external name for the
# "gauss" routine has been encoded in the object file:
$ nm a.o
U Gauss
0000000000000000 T MAIN__
U _gfortran_set_options
0000000000000000 r options.0.1534
Hope this helps,
--
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
Saturnushof 14, 3738 XG Maartensdijk, The Netherlands
At home: http://moene.org/~toon/
Progress of GNU Fortran: http://gcc.gnu.org/gcc-4.5/changes.html
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine
2010-03-30 17:50 Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine Glenn H Sembroski
2010-03-30 23:58 ` Harald Servat
@ 2010-03-31 11:29 ` Axel Freyn
1 sibling, 0 replies; 5+ messages in thread
From: Axel Freyn @ 2010-03-31 11:29 UTC (permalink / raw)
To: gcc-help
Hi Glenn,
On Tue, Mar 30, 2010 at 11:15:27AM -0400, Glenn H Sembroski wrote:
> I have a problem trying to prepare a large simulation package, using
> mixed F90 and C++ routines, to compile and build under GCC (g++, and
> gfortran). The problem is I have a C++ function: Gauss() which is
> called from an F90 routine:
> x=gauss()
>
> This package was made able to build under the Intel fortran compiler by
> adding to the fortran file the Intel compile directive:
>
> !DEC$ ATTRIBUTES ALIAS:'Gauss' :: gauss
>
> I attempted to build this program using GCC where for F90 code the
> gfortran compiler option -fno-underscoring was used.
>
> Presently my fortran routine won't build. It gets the error:
>
> 485: undefined reference to `gauss'
>
> So, my question is, is there a way in GCC to enable the linker to find
> the C++ 'Gauss' method?
Well, just a possibility: C++-functions are something special (due to
the possibility that they can be overloaded e.g.), you can't call them
directly from C or F77 - and I think F90 might have the same problem: A
C++-Function "Gauss" will NOT be called "gauss" for linking - but
instead it will have a much longer name depending on its parameters...
You have to mark the C++-function as e.g. extern "C" void Gauss(); in
order to be able to call it from C or F77 (and probably also for calls
from F90?)
Axel
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2010-03-30 17:50 Accessing C++ function with Mixed Upper/Lower case name from F90 subroutine Glenn H Sembroski
2010-03-30 23:58 ` Harald Servat
2010-03-31 11:33 ` Toon Moene
2010-03-31 12:51 ` Tobias Burnus
2010-03-31 11:29 ` Axel Freyn
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