Applying a pre-processor macro to a single source with cmake

Usage
1

Hello,

I am using cmake to build my Fortran project, and I am trying to set a pre-processor macro on a single file, using set_source_files_properties. It works (the cpp flag is there when I compile the code), but cmake does not compute the dependencies properly.

Here is the sample code :

[ECA defines]$ cat CMakeLists.txt 
cmake_minimum_required (VERSION 3.22)

project (cmkpack LANGUAGES Fortran)

set_source_files_properties (a.F90 PROPERTIES COMPILE_DEFINITIONS DEF) 

add_library (AB OBJECT a.F90 b.F90)

[ECA defines]$ cat a.F90
MODULE A

CONTAINS

#ifdef DEF

SUBROUTINE RR

USE B

IMPLICIT NONE

END SUBROUTINE RR

#endif

END 
[ECA defines]$ cat b.F90
MODULE B

REAL :: X, Y, Z, T, W

CONTAINS

SUBROUTINE S
END SUBROUTINE

END

when I run cmake and try to compile, I get this :

[ECA defines]$ cmake --version
cmake version 3.28.2

CMake suite maintained and supported by Kitware (kitware.com/cmake).
[ECA defines]$ cmake .
-- The Fortran compiler identification is GNU 4.8.5
-- Detecting Fortran compiler ABI info
-- Detecting Fortran compiler ABI info - done
-- Check for working Fortran compiler: /usr/bin/f95 - skipped
-- Configuring done (0.4s)
-- Generating done (0.0s)
-- Build files have been written to: /home/gmap/mrpm/marguina/tmp/cmk3/defines
[ECA defines]$ make VERBOSE=1
...
[ 50%] Building Fortran object CMakeFiles/AB.dir/a.F90.o
/usr/bin/f95  -DDEF   -c /home/gmap/mrpm/marguina/tmp/cmk3/defines/a.F90 -o CMakeFiles/AB.dir/a.F90.o
/home/gmap/mrpm/marguina/tmp/cmk3/defines/a.F90:9.4:

USE B
    1
Fatal Error: Can't open module file 'b.mod' for reading at (1): No such file or directory
make[2]: *** [CMakeFiles/AB.dir/a.F90.o] Error 1

So apparently, cmake fails to compute dependencies. If I remove the #ifdef/#endif in a.F90, then it works.

Is it a know feature of cmake ? (Or a bug ?) Is there a possibility to solve this problem ?

Please note that :

  • it works if I use set_target_properties on AB
  • having a.F90 and b.F90 in separate targets is not possible

Thank you for your help