[CMake] Problem with Fortran module enclosed in #ifdef

[Michael Wild]

On 9. Jan, 2009, at 10:26, Martin Apel wrote:

> Michael Wild wrote:
>> On 9. Jan, 2009, at 9:27, Martin Apel wrote:
>>
>>
>>> Hi all,
>>>
>>> I am experiencing a problem with one Fortran source file  
>>> containing a
>>> module definition. Unfortunately the whole source file is enclosed  
>>> in
>>> '#ifdef WINDOWS'. On Linux this causes the build process to fail,
>>> because cmake wants to copy a generated .mod file, which does not
>>> exist.
>>> The file containing the module has the suffix ".f". When changing  
>>> the
>>> suffix to ".F", everything works fine.
>>> CMake probably thinks, the file need not be preprocessed before
>>> scanning, if it has the suffix ".f". Is there any way to tell CMake,
>>> that files with the suffix ".f" have to be preprocessed before
>>> dependency scanning?
>>>
>>> Regards,
>>>
>>> Martin
>>>
>>>
>>
>> Hi
>>
>> I think it is fairly non-standard to have a .f file preprocessed. All
>> Fortran compilers I'm acquainted with only preprocess a file if it  
>> has
>> a .F extension (unless forced, of course).
>>
>> But since it is the whole file, can't you just exclude it in the  
>> CMake
>> code?
>>
>> set( SRCS foo.f bar.f )
>> if(WIN32)
>>   list( APPEND SRCS winspecific.f )
>> endif(WIN32)
>>
>> add_executable( super_cow ${SRCS} )
>>
> You are right, that this is uncommon. But I'm trying to replace an
> existing "build system" for some thousands of files, which  
> preprocesses
> all Fortran files, even those with ".f" suffix. Unfortunately this is
> something I can't change.
> I could use the approach you suggest, but I'd like a more general
> solution, because I cannot be sure, that this is the only file, where
> preprocessing makes a difference. There might
> be other files containing a USE directive enclosed in ifdefs.
>
> Regards,
>
> Martin
>

I just constructed a small test case, and it works for me (using  
CMake-2.6 and gfortran). See below.

Michael

test.f90:
=========

program test
#ifdef MORE
   use test_module
#endif
   implicit none

   print *, "This is a test"

#ifdef MORE
   call hello()
#endif

end program test


modules/test_module.f90
=======================

#ifdef MORE
module test_module
   implicit none
   contains
   subroutine hello()
     implicit none
     print *,"Hello World"
   end subroutine
end module test_module
#endif


CMakeLists.txt
==============

project( test Fortran )

cmake_minimum_required( VERSION 2.6 )

option( DEFINE_MORE "If set to ON, -DMORE will be defined" OFF )
# force gfortran to preprocess the input files
# change this to "-fpp" for ifort (that's the ones i know...)
set( FORTRAN_PREPROCESS_FLAG "-x f95-cpp-input" CACHE STRING
   "Flags to force the Fortran compiler to preprocess the source  
files.")

if( DEFINE_MORE )
   add_definitions( -DMORE )
endif( DEFINE_MORE )

add_executable( test test.f90 modules/test_module.f90 )

set_target_properties( test PROPERTIES COMPILE_FLAGS $ 
{FORTRAN_PREPROCESS_FLAG} ))