We will now discuss the corresponding CMake structure:

1. The top-level CMakeLists.txt is similar to Recipe 7; we only exchange CXX for Fortran and remove the C++11 requirement:

cmake_minimum_required(VERSION 3.5 FATAL_ERROR)

project(recipe-09 LANGUAGES Fortran)

include(GNUInstallDirs)
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY
  ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY
  ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY
  ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR})

# defines targets and sources
add_subdirectory(src)

# contains an "external" library we will link to
add_subdirectory(external)

# enable testing and define tests
enable_testing()
add_subdirectory(tests)

2. Targets and sources are defined in src/CMakeLists.txt (except the conversion target):

add_executable(automata main.f90)
  
add_subdirectory(evolution)
add_subdirectory(initial)
add_subdirectory(io)
add_subdirectory(parser)

target_link_libraries(automata
  PRIVATE
    conversion
    evolution
    initial
    io
    parser
  )

3. The conversion library is defined in external/CMakeLists.txt:

add_library(conversion "")
  
target_sources(conversion
  PUBLIC
    ${CMAKE_CURRENT_LIST_DIR}/conversion.f90
  )

4. The src/CMakeLists.txt file adds further subdirectories, which in turn contain CMakeLists.txt files. They are all similar in structure; for example, src/initial/CMakeLists.txt contains the following:

add_library(initial "")
  
target_sources(initial
  PUBLIC
    ${CMAKE_CURRENT_LIST_DIR}/initial.f90
  )

5. The exception is the evolution library in src/evolution/CMakeLists.txt, which we have split into three source files:

add_library(evolution "")
  
target_sources(evolution
  PRIVATE
    empty.f90
  PUBLIC
    ${CMAKE_CURRENT_LIST_DIR}/ancestors.f90
    ${CMAKE_CURRENT_LIST_DIR}/evolution.f90
  )

6. The unit tests are registered in tests/CMakeLists.txt:

add_executable(fortran_test test.f90)

target_link_libraries(fortran_test evolution)

add_test(
  NAME
    test_evolution
  COMMAND
    $<TARGET_FILE:fortran_test>
  )

7. Configuring and building the project yields the following output:

$ mkdir -p build
$ cd build
$ cmake ..
$ cmake --build .

Scanning dependencies of target conversion
[ 4%] Building Fortran object external/CMakeFiles/conversion.dir/conversion.f90.o
[ 8%] Linking Fortran static library ../lib64/libconversion.a
[ 8%] Built target conversion
Scanning dependencies of target evolution
[ 12%] Building Fortran object src/evolution/CMakeFiles/evolution.dir/ancestors.f90.o
[ 16%] Building Fortran object src/evolution/CMakeFiles/evolution.dir/empty.f90.o
[ 20%] Building Fortran object src/evolution/CMakeFiles/evolution.dir/evolution.f90.o
[ 25%] Linking Fortran static library ../../lib64/libevolution.a
[ 25%] Built target evolution
Scanning dependencies of target initial
[ 29%] Building Fortran object src/initial/CMakeFiles/initial.dir/initial.f90.o
[ 33%] Linking Fortran static library ../../lib64/libinitial.a
[ 33%] Built target initial
Scanning dependencies of target io
[ 37%] Building Fortran object src/io/CMakeFiles/io.dir/io.f90.o
[ 41%] Linking Fortran static library ../../lib64/libio.a
[ 41%] Built target io
Scanning dependencies of target parser
[ 45%] Building Fortran object src/parser/CMakeFiles/parser.dir/parser.f90.o
[ 50%] Linking Fortran static library ../../lib64/libparser.a
[ 50%] Built target parser
Scanning dependencies of target example
[ 54%] Building Fortran object src/CMakeFiles/example.dir/__/external/conversion.f90.o
[ 58%] Building Fortran object src/CMakeFiles/example.dir/evolution/ancestors.f90.o
[ 62%] Building Fortran object src/CMakeFiles/example.dir/evolution/evolution.f90.o
[ 66%] Building Fortran object src/CMakeFiles/example.dir/initial/initial.f90.o
[ 70%] Building Fortran object src/CMakeFiles/example.dir/io/io.f90.o
[ 75%] Building Fortran object src/CMakeFiles/example.dir/parser/parser.f90.o
[ 79%] Building Fortran object src/CMakeFiles/example.dir/main.f90.o
[ 83%] Linking Fortran executable ../bin/example
[ 83%] Built target example
Scanning dependencies of target fortran_test
[ 87%] Building Fortran object tests/CMakeFiles/fortran_test.dir/__/src/evolution/ancestors.f90.o
[ 91%] Building Fortran object tests/CMakeFiles/fortran_test.dir/__/src/evolution/evolution.f90.o
[ 95%] Building Fortran object tests/CMakeFiles/fortran_test.dir/test.f90.o
[100%] Linking Fortran executable

8. Finally, we run the unit tests:

$ ctest

Running tests...
 Start 1: test_evolution
1/1 Test #1: test_evolution ................... Passed 0.00 sec

100% tests passed, 0 tests failed out of 1