[CMake] Mixing C/CPP and Fortran

[Alin M Elena]

Hi Kyle,

My personal opinion is that cmake should handle correctly and generate a 
binary in this case. libhello.a is generated by the project and is intended 
for the use within the project so cmake should do it.

with shared libs things are ok.

regards,

Alin


-- 
 ______________________________________________________________________
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 ______________________________________________________________________
 Mr  Alin M ELENA
 Irish Centre for High-End Computing -- www.ichec.ie
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 ______________________________________________________________________
On Tuesday 26 May 2009 18:12:13 you wrote:
> On Tue, 26 May 2009 18:01:17 +0100
>
> Alin M Elena <alinm.elena at googlemail.com> wrote:
> > Hi All,
> >
> >
> > I try to mix some C and Fortran (I know not such a good idea).
> >
> > Anyhow I create a project and then use cmake to manage the build. (see
> > attach) C is the main language, if I may say so, It links.
> >
> > I get a linking error
> > Linking C executable bin/testme
> > /usr/bin/cmake -E cmake_link_script CMakeFiles/testme.dir/link.txt
> > --verbose=1 /usr/bin/gcc    -fPIC CMakeFiles/testme.dir/source/main.c.o 
> > -o bin/testme - rdynamic lib/libhello.a
> > lib/libhello.a(libhello.f90.o): In function `hello':
> > libhello.f90:(.text+0x43): undefined reference to `_gfortran_st_write'
> > libhello.f90:(.text+0x59): undefined reference to
> > `_gfortran_transfer_character'
> > libhello.f90:(.text+0x71): undefined reference to
> > `_gfortran_transfer_integer' libhello.f90:(.text+0x7d): undefined
> > reference to `_gfortran_st_write_done' collect2: ld returned 1 exit
> > status
> > make[2]: *** [bin/testme] Error 1
> > make[2]: Leaving directory `/home/alin/playground/mixCFortran/build'
> > make[1]: *** [CMakeFiles/testme.dir/all] Error 2
> > make[1]: Leaving directory `/home/alin/playground/mixCFortran/build'
> > make: *** [all] Error 2
> >
> >
> > The problem is very easy solvable by just linking against the fortran
> > runtime libs (/usr/lib64/libgfortran.so) in this case (gnu compilers).
> >
> > My question is. Shouldn't cmake handle this internally, so the user does
> > not bother about?
> >
> > regards,
> >
> > Alin
>
> I don't think that it is desirable to have cmake automatically link in this
> case.  It looks like libhello.a is build from at least some fortran, thus
> causing the requirement for libgfortran, but how whould cmake know what to
> do?  Would it keep track of the fact the fortran was used to build
> libhello.a and then automatically append -lgfortran to any program which
> also links to libhello.a?  It may be better for the developers to remember
> the dependency and handle it themselves, even though that is more work for
> us. I'm not sure that cmake would know what libraries need to be linked
> when using more exotic fortran compilers(PGI, intel, absoft, nag, salford,
> etc).  Does it cause linking errors when libhello is compiled as a shared
> library too?