[CMake] Fortan and C++

Michael Wild themiwi at gmail.com
Sun Aug 23 05:20:15 EDT 2009 

I think you called the CREATE_FORTRAN_C_INTERFACE function  
incorrectly. The second argument needs to be the name of a variable  
containing a list of function names:

SET( FUNCTIONS cross )
CREATE_FORTRAN_C_INTERFACE( myf FUNCTIONS ${CMAKE_CURRENT_BINARY_DIR}/ 
myconfig.h )

Michael



On 22. Aug, 2009, at 20:24, Dominik Szczerba wrote:

> Of course, you are right - not about ifcore that is resolved by ldd,  
> but about the multibyte magic. I applied your patch. Now I get:
>
> -- checking Fortran function linkage: sub_
> -- found Fortran function linkage
> -- checking Fortran function with _  linkage: my_sub_
> -- checking Fortran module linkage: test_interface$sub
> -- checking Fortran module linkage: TEST_INTERFACE_mp_sub
> -- checking Fortran module linkage: _test_interface__sub
> -- checking Fortran module linkage: __test_interface__sub
> -- checking Fortran module linkage: __test_interface_NMOD_sub
> -- checking Fortran module linkage: __test_interface_MOD_sub
> -- Failed to find C binding to Fortran module functions.
> -- Failed to find Fortran module linkage
> -- created myfconfig.h
>
> The content of myfconfig.h file:
>
> /* This file is automatically generated by CMake, DO NOT EDIT.
>   It contains a mapping from Fortran functions so they can
>   be called from C or C++.   */
>
> Where do I go from here?
>
> Many thanks,
> Dominik
>
> Michael Wild wrote:
>> As I said, FortranCInterface.cmake is buggy as it doesn't pass the   
>> CMAKE_Fortran_FLAGS and CMAKE_EXE_LINKER_FLAGS variables to the   
>> TRY_COMPILE project. If you have to set these in order to compile/ 
>> link  a mixed-language program, it fails. Come to think of it, in  
>> your case  the ifcore library will also be missing, so probably  
>> something like a  CMAKE_REQUIRED_LIBRARIES variable will also be  
>> necessary.
>> Michael
>> On 22. Aug, 2009, at 15:40, Dominik Szczerba wrote:
>>> I naively tried:
>>>
>>> INCLUDE(FortranCInterface)
>>> CREATE_FORTRAN_C_INTERFACE(myf cross myfconfig.h)
>>>
>>> to get:
>>>
>>> -- checking Fortran function linkage: sub_
>>> -- checking Fortran function linkage: _sub_
>>> -- checking Fortran function linkage: __sub_
>>> -- checking Fortran function linkage: SUB_
>>> -- checking Fortran function linkage: _SUB_
>>> -- checking Fortran function linkage: __SUB_
>>> -- checking Fortran function linkage: sub
>>> -- checking Fortran function linkage: _sub
>>> -- checking Fortran function linkage: __sub
>>> -- checking Fortran function linkage: SUB
>>> -- checking Fortran function linkage: _SUB
>>> -- checking Fortran function linkage: __SUB
>>> CMake Error at /usr/local/share/cmake-2.6/Modules/  
>>> FortranCInterface.cmake:169 (message):
>>> Could not find fortran c name mangling.
>>> Call Stack (most recent call first):
>>> CMakeLists.txt:34 (create_fortran_c_interface)
>>>
>>> I have C CXX and Fortran enabled in the 'project' call. Using  
>>> icpc/ ifort 11.x
>>>
>>> - Dominik
>>>
>>> Dominik Szczerba wrote:
>>>> Hi Michael,
>>>> Michael Wild wrote:
>>>>> Hi Dominik
>>>>>
>>>>> Concerning the flags: you should add the -no-multibyte-chars to   
>>>>> the  CMAKE_CXX_FLAGS variable. This will get prepended to all    
>>>>> CMAKE_CXX_FLAGS_{RELEASE,DEBUG,...} flags, since you don't want   
>>>>> this  flag to be used for the Release configuration  
>>>>> exclusively,  but for all  configurations.
>>>> Thanks for the clarifications.
>>>>> Linking against ifcore using the C++ compiler only works if it  
>>>>> is  on  the search path (probably by sourcing ifortvars.sh),  
>>>>> otherwise  you'll  have to specify it's full path. I think,  
>>>>> Intel recommends  using the  the Fortran compiler for linking  
>>>>> instead, and passing  it the -cxxlib  and -nofor_main flags  
>>>>> (those are the correct names  now, I looked them  up ;-)).
>>>> I see, will maybe try some day. However, I have no problem  
>>>> linking  for the moment.
>>>>> On Mac platforms there is another problem: By default the g++   
>>>>> compiler  generates 32-bit code, while the Intel Fortran  
>>>>> compiler  generates 64- bit code (very annoying).
>>>>>
>>>>> If you try to use FortranCInterface.cmake, be aware that it is   
>>>>> quite  buggy, as it doesn't pass the CMAKE_*_FLAGS to the   
>>>>> try_compile calls.  Further it doesn't ensure that the C  
>>>>> language  is enabled, altough it  is calling try_compile on C  
>>>>> code! I'll  file a bug report with an  attached patch for that.
>>>>>
>>>> This is new to me. Sounds like automatic handling of calling   
>>>> decorations. Would be great! Are there any examples how to use  
>>>> it?  Do I still need it when I know the mangling scheme myself?  
>>>> Can I  set the pre/suffixes myself in some elegant manner?  
>>>> Currently I am  just hacking on my own, so indications how to  
>>>> position myself for  the future are very welcome.
>>>> Thanks,
>>>> Dominik
>>>>> All the best
>>>>>
>>>>> Michael
>>>>>
>>>>> On 22. Aug, 2009, at 13:35, Dominik Szczerba wrote:
>>>>>
>>>>>> Here the report of my tests:
>>>>>>
>>>>>> Just ignorant approach (don't google):
>>>>>>
>>>>>> It works out of the box on linux with intel compilers 10.x.  
>>>>>> Just  add  Fortran to the languages in the project signature  
>>>>>> and add  STUFF.F90  to the source files. You need to link to  
>>>>>> ifcore  library though.
>>>>>>
>>>>>> It does not work out of the box with the compilers 11.x. Here   
>>>>>> the  ignorant approach failed. The errors were like:
>>>>>>
>>>>>> -- Check for working CXX compiler: /usr/local/bin/icpc-11.0.083
>>>>>> -- Check for working CXX compiler: /usr/local/bin/ 
>>>>>> icpc-11.0.083  --  broken
>>>>>> CMake Error at /usr/local/share/cmake-2.6/Modules/   
>>>>>> CMakeTestCXXCompiler.cmake:25 (MESSAGE):
>>>>>> The C++ compiler "/usr/local/bin/icpc-11.0.083" is not able  
>>>>>> to   compile a
>>>>>> simple test program.
>>>>>>
>>>>>> It fails with the following output:
>>>>>>
>>>>>> Change Dir: /home/domel/build/solve/CMakeFiles/CMakeTmp
>>>>>>
>>>>>> Checking by foot what the compilers at all say during   
>>>>>> compilations I  found:
>>>>>>
>>>>>>> icpc-11.0.083 -c test.cxx
>>>>>> Catastrophic error: could not set locale "" to allow  
>>>>>> processing  of  multibyte characters
>>>>>>
>>>>>> Googling reveals a bug in the compiler to be circumvented  
>>>>>> with   adding '-no-multibyte-chars' to the compiler switches.  
>>>>>> However,   adding this to my CMAKE_XXX_FLAGS_RELEASE (my  
>>>>>> CMAKE_BUILD_TYPE  is  RELEASE) does not help. I must now either  
>>>>>> specify  CMAKE_XXX_FLAGS  explicitly on the commandline or in  
>>>>>> the cache.  Probably because  cmake uses default flags  
>>>>>> (CMAKE_XXX_FLAGS) for  compiler checks, even  if  
>>>>>> CMAKE_BUILD_TYPE is explicitly set  release/debug (as well as   
>>>>>> corresponding release/debug flags).
>>>>>>
>>>>>> Maybe cmake should use compiler flags as defined by   
>>>>>> CMAKE_BUILD_TYPE  to check for compilers?
>>>>>>
>>>>>> - Dominik
>>>>>>
>>>>>>
>>>>>>
>>>>>> Dominik Szczerba wrote:
>>>>>>> Michael,
>>>>>>> Many thanks for the feedback.
>>>>>>> What I am doing with a GNU makefile so far is compile just  
>>>>>>> one  file  with the fortran compiler use C++ linker to link  
>>>>>>> all  object files  as usual.
>>>>>>> A comprehensive solution I would expect in cmake would be 1)    
>>>>>>> nothing (.f90 file is understood) or something along the  
>>>>>>> lines  of  setting the file properties (sort of 'to be  
>>>>>>> compiler with'  flag)...
>>>>>>> - Dominik
>>>>>>> Michael Wild wrote:
>>>>>>>> On 21.08.2009, at 17:57, Dominik Szczerba  <dominik at itis.ethz.ch 
>>>>>>>> >  wrote:
>>>>>>>>
>>>>>>>>> I want to compile one file with fortran compiler (intel)  
>>>>>>>>> and   link  with the rest of my project. Will the latest  
>>>>>>>>> cmake allow  to  fully  cmakify such scenario?
>>>>>>>> Hi Dominik
>>>>>>>>
>>>>>>>> If I remember correctly, you'll have to set the  
>>>>>>>> LINK_LANGUAGE   property  of your target to Fortran and then  
>>>>>>>> ensure that the   Fortran linker also  links against the C++  
>>>>>>>> standard library.  For  Intel this would be -stdc+ + (or some  
>>>>>>>> such). If you are  creating  an executable, depending on   
>>>>>>>> where your main-function  is defined,  you might also need to  
>>>>>>>> tell the  linker to not add  a Fortran main- function, the  
>>>>>>>> flag is called - nofor_main if I  remember correctly.   
>>>>>>>> Otherwise the ifort man-page will  tell  you :)
>>>>>>>>
>>>>>>>>
>>>>>>>> HTH
>>>>>>>>
>>>>>>>> Michael
>>>>>> -- 
>>>>>> d o m i n i k   s z c z e r b a ,   p h d . . . . . . . . . . .
>>>>>> c o m p u t a t i o n a l   l i f e   s c i e n c e   g r o u p
>>>>>> . . . . . . . i t ' i s   r e s e a r c h   f o u n d a t i o n
>>>>>> . . . . . . . . . . . . . . . . . . . . http://www.itis.ethz.ch
>>>>>>
>>>
>>> -- 
>>> d o m i n i k   s z c z e r b a ,   p h d . . . . . . . . . . .
>>> c o m p u t a t i o n a l   l i f e   s c i e n c e   g r o u p
>>> . . . . . . . i t ' i s   r e s e a r c h   f o u n d a t i o n
>>> . . . . . . . . . . . . . . . . . . . . http://www.itis.ethz.ch
>>>
>
>
> -- 
> d o m i n i k   s z c z e r b a ,   p h d . . . . . . . . . . .
> c o m p u t a t i o n a l   l i f e   s c i e n c e   g r o u p
> . . . . . . . i t ' i s   r e s e a r c h   f o u n d a t i o n
> . . . . . . . . . . . . . . . . . . . . http://www.itis.ethz.ch
>

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