Check if the compiler has the <span> header

src/algorithms/libs/CMakeLists.txt

@@ -92,7 +92,15 @@ else()
     target_link_libraries(algorithms_libs PRIVATE Boost::filesystem Boost::system)
 endif()
 
-if(NOT (CMAKE_CXX_STANDARD VERSION_LESS 20))
+include(CheckCXXSourceCompiles)
+check_cxx_source_compiles("
+    #include <span>
+    int main()
+    { std::span<float> sv; }"
+    has_span
+)
+
+if(${has_span})
     target_compile_definitions(algorithms_libs PUBLIC -DHAS_SPAN=1)
 else()
     target_include_directories(algorithms_libs