[CMake] Fortan and C++

Dominik Szczerba dominik at itis.ethz.ch
Sat Aug 22 14:24:16 EDT 2009 

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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