ENH: filesystem detection

Author: zap150

CMakeLists.txt

@@ -7,6 +7,7 @@ list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/cmake/Modules)
 check_insource()
 setup_compiler()
 
+enable_filesystem()
 enable_MKL()
 enable_MPI()
 enable_OpenMP()

cmake/has_stdfs.cpp

@@ -0,0 +1,11 @@
+// Check if std::filesystem is available
+// Source: https://stackoverflow.com/a/54290906
+// with modifications
+
+#include <filesystem>
+
+int main( int /*argc*/, char ** /*argv[]*/ ) {
+  std::filesystem::path somepath{ "dir1/dir2/filename.txt" };
+  auto fname = somepath.filename( );
+  return 0;
+}

cmake/macros.cmake

@@ -15,12 +15,8 @@ macro(setup_compiler)
 
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic-errors")
-    
-    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0)
-      link_libraries(stdc++fs)
-    endif()
+
   elseif (CMAKE_CXX_COMPILER_ID MATCHES Intel)
-    # link_libraries(stdc++fs)
     if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.0.1)
       message(FATAL_ERROR "Intel compiler is too old, besthea can be"
         " compiled only with icpc 19.0.1 or higher")
@@ -60,6 +56,34 @@ macro(setup_compiler)
   add_compile_definitions(DATA_WIDTH=${DATA_WIDTH})
 endmacro()
 
+macro(enable_filesystem)
+  # try without -lstd++fs
+  try_run(RUNS_WITH_STDFS COMPILES_WITH_STDFS
+    "${CMAKE_BINARY_DIR}/try"
+    "${CMAKE_SOURCE_DIR}/cmake/has_stdfs.cpp"
+    CMAKE_FLAGS -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=ON
+    RUN_OUTPUT_VARIABLE TRY_OUTPUT)
+
+  if (NOT COMPILES_WITH_STDFS OR RUNS_WITH_STDFS STREQUAL "FAILED_TO_RUN")
+    # try with -lstd++fs
+    try_run(RUNS_WITH_STDFS COMPILES_WITH_STDFS
+      "${CMAKE_BINARY_DIR}/try"
+      "${CMAKE_SOURCE_DIR}/cmake/has_stdfs.cpp"
+      CMAKE_FLAGS -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=ON
+      LINK_LIBRARIES stdc++fs
+      RUN_OUTPUT_VARIABLE TRY_OUTPUT)
+
+      if (NOT COMPILES_WITH_STDFS OR RUNS_WITH_STDFS STREQUAL "FAILED_TO_RUN")
+        message(FATAL_ERROR "No std::filesystem support")
+      else()
+        message(STATUS "Found std::filesystem: libstdc++fs")
+        link_libraries(stdc++fs)
+      endif()
+  else()
+    message(STATUS "Found std::filesystem: libstdc++")
+  endif()
+endmacro()
+
 # also adds flag to linker, but we want to link against iomp5
 #macro(enable_OpenMP)
 #  find_package(OpenMP REQUIRED)

test/test_ensight_export/test_ensight_export.cpp

@@ -72,7 +72,7 @@ int main( int argc, char * argv[] ) {
     }
 
     for ( lo i = 0; i < mesh.get_n_elements( ); ++i ) {
-      something_data[ i ] = sin( (double)i ) * cos( (double)ts );
+      something_data[ i ] = sin( (double) i ) * cos( (double) ts );
     }
   }