[CMake] Fortan and C++

Sat Aug 22 09:29:27 EDT 2009

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
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>> . . . . . . . . . . . . . . . . . . . . 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