Check using Visual Studio without setting /std:

Author: d-frey

include/tao/json/external/string_view.hpp

@@ -8,9 +8,11 @@
 #if( __cplusplus >= 201703L )
 #define TAOCPP_USE_STD_STRING_VIEW
 #elif defined( _MSC_VER ) && ( _MSC_VER >= 1910L )
+#if defined( _MSC_LANG ) && ( _MSC_LANG >= 201703L )
 #define TAOCPP_USE_STD_STRING_VIEW
 #endif
 #endif
+#endif
 
 #ifndef TAOCPP_USE_STD_STRING_VIEW
 #ifndef TAOCPP_USE_TS_STRING_VIEW

src/test/json/CMakeLists.txt

@@ -7,7 +7,7 @@ foreach (testsourcefile ${testsources})
   set_property (TARGET ${exename} PROPERTY CXX_EXTENSIONS OFF)
   target_link_libraries (${exename} taocpp::json)
   if (MSVC)
-    target_compile_options (${exename} PRIVATE /std:c++17 /W4 /WX /utf-8)
+    target_compile_options (${exename} PRIVATE /W4 /WX /utf-8)
   else ()
     target_compile_options (${exename} PRIVATE -pedantic -Wall -Wextra -Wshadow -Werror)
   endif ()