build(examples): Link HeFFTe to all example targets

Add HeFFTe to link dependencies for all examples since they
use OpenPFC which now links HeFFTe privately, requiring
explicit linking to resolve HeFFTe symbols at link time.

- Define _heffte_tgt variable with target fallback logic
- Add _heffte_tgt to all example target_link_libraries

Author: ahojukka5

examples/CMakeLists.txt

@@ -3,7 +3,16 @@
 
 # FFT Backend Benchmark (requires MPI)
 add_executable(fft_backend_benchmark fft_backend_benchmark.cpp)
-target_link_libraries(fft_backend_benchmark PRIVATE OpenPFC)
+set(_heffte_tgt "")
+if(TARGET Heffte::Heffte)
+  set(_heffte_tgt Heffte::Heffte)
+elseif(TARGET Heffte)
+  set(_heffte_tgt Heffte)
+elseif(TARGET heffte)
+  set(_heffte_tgt heffte)
+endif()
+
+target_link_libraries(fft_backend_benchmark PRIVATE OpenPFC ${_heffte_tgt})
 if(OpenPFC_ENABLE_CUDA)
   target_compile_definitions(fft_backend_benchmark PRIVATE OpenPFC_ENABLE_CUDA)
 endif()
@@ -12,73 +21,73 @@ endif()
 # target_link_libraries(01_hello_world PRIVATE OpenPFC)
 
 add_executable(02_domain_decomposition 02_domain_decomposition.cpp)
-target_link_libraries(02_domain_decomposition PRIVATE OpenPFC)
+target_link_libraries(02_domain_decomposition PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(03_parallel_fft 03_parallel_fft.cpp)
-target_link_libraries(03_parallel_fft PRIVATE OpenPFC)
+target_link_libraries(03_parallel_fft PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(04_diffusion_model 04_diffusion_model.cpp)
-target_link_libraries(04_diffusion_model PRIVATE OpenPFC)
+target_link_libraries(04_diffusion_model PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(05_simulator 05_simulator.cpp)
-target_link_libraries(05_simulator PRIVATE OpenPFC)
+target_link_libraries(05_simulator PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(06_multi_index 06_multi_index.cpp)
-target_link_libraries(06_multi_index PRIVATE OpenPFC)
+target_link_libraries(06_multi_index PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(07_array 07_array.cpp)
-target_link_libraries(07_array PRIVATE OpenPFC)
+target_link_libraries(07_array PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(08_discrete_fields 08_discrete_fields.cpp)
-target_link_libraries(08_discrete_fields PRIVATE OpenPFC)
+target_link_libraries(08_discrete_fields PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(09_parallel_fft_high_level 09_parallel_fft_high_level.cpp)
-target_link_libraries(09_parallel_fft_high_level PRIVATE OpenPFC)
+target_link_libraries(09_parallel_fft_high_level PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(10_ui_register_ic 10_ui_register_ic.cpp)
-target_link_libraries(10_ui_register_ic PRIVATE OpenPFC nlohmann_json::nlohmann_json)
+target_link_libraries(10_ui_register_ic PRIVATE OpenPFC nlohmann_json::nlohmann_json ${_heffte_tgt})
 
 add_executable(11_write_results 11_write_results.cpp)
-target_link_libraries(11_write_results PRIVATE OpenPFC)
+target_link_libraries(11_write_results PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(12_cahn_hilliard 12_cahn_hilliard.cpp)
-target_link_libraries(12_cahn_hilliard PRIVATE OpenPFC nlohmann_json::nlohmann_json)
+target_link_libraries(12_cahn_hilliard PRIVATE OpenPFC nlohmann_json::nlohmann_json ${_heffte_tgt})
 
 add_executable(fft_kspace_helpers_example fft_kspace_helpers_example.cpp)
-target_link_libraries(fft_kspace_helpers_example PRIVATE OpenPFC)
+target_link_libraries(fft_kspace_helpers_example PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(mpi_worker mpi_worker.cpp)
-target_link_libraries(mpi_worker PRIVATE OpenPFC)
+target_link_libraries(mpi_worker PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(mpi_worker_inside_class mpi_worker_inside_class.cpp)
-target_link_libraries(mpi_worker_inside_class PRIVATE OpenPFC)
+target_link_libraries(mpi_worker_inside_class PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(mpi_timers mpi_timers.cpp)
-target_link_libraries(mpi_timers PRIVATE OpenPFC)
+target_link_libraries(mpi_timers PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(time time.cpp)
-target_link_libraries(time PRIVATE OpenPFC)
+target_link_libraries(time PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(write_results write_results.cpp)
-target_link_libraries(write_results PRIVATE OpenPFC)
+target_link_libraries(write_results PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(diffusion_model_with_custom_initial_condition diffusion_model_with_custom_initial_condition.cpp)
-target_link_libraries(diffusion_model_with_custom_initial_condition PRIVATE OpenPFC)
+target_link_libraries(diffusion_model_with_custom_initial_condition PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(json_read json_read.cpp)
 target_link_libraries(json_read PRIVATE nlohmann_json::nlohmann_json)
 
 add_executable(world_helpers_example world_helpers_example.cpp)
-target_link_libraries(world_helpers_example PRIVATE OpenPFC)
+target_link_libraries(world_helpers_example PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(14_custom_field_initializer 14_custom_field_initializer.cpp)
-target_link_libraries(14_custom_field_initializer PRIVATE OpenPFC)
+target_link_libraries(14_custom_field_initializer PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(16_strong_types_demo 16_strong_types_demo.cpp)
-target_link_libraries(16_strong_types_demo PRIVATE OpenPFC)
+target_link_libraries(16_strong_types_demo PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(17_custom_coordinate_system 17_custom_coordinate_system.cpp)
-target_link_libraries(17_custom_coordinate_system PRIVATE OpenPFC)
+target_link_libraries(17_custom_coordinate_system PRIVATE OpenPFC ${_heffte_tgt})
 
 add_executable(world_strong_types_example world_strong_types_example.cpp)
-target_link_libraries(world_strong_types_example PRIVATE OpenPFC)
+target_link_libraries(world_strong_types_example PRIVATE OpenPFC ${_heffte_tgt})