Add BOOST_PROCESS_USE_STD_FS option

Author: yurybura

CMakeLists.txt

@@ -7,6 +7,8 @@ cmake_minimum_required(VERSION 3.5...3.16)
 
 project(boost_process VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
 
+option(BOOST_PROCESS_USE_STD_FS "Use std::filesystem instead of Boost.Filesystem" OFF)
+
 add_library(boost_process
         src/detail/environment_posix.cpp
         src/detail/environment_win.cpp
@@ -49,13 +51,14 @@ target_compile_definitions(boost_process
         PRIVATE BOOST_PROCESS_SOURCE=1
 )
 
-if (BOOST_PROCESS_USE_STD_FS)
-  target_compile_definitions(boost_process PUBLIC BOOST_PROCESS_USE_STD_FS=1 )
+if(BOOST_PROCESS_USE_STD_FS)
+  target_compile_definitions(boost_process PUBLIC BOOST_PROCESS_USE_STD_FS)
+  target_compile_features(boost_process PUBLIC cxx_std_17)
 else()
   target_link_libraries(boost_process PUBLIC Boost::filesystem)
 endif()
 
-if (WIN32)
+if(WIN32)
   target_link_libraries(boost_process PUBLIC ntdll shell32 advapi32 user32 ws2_32)
 endif()