Merge pull request #683 from redboltz/fix_658

Fixed #658.

Author: redboltz

include/msgpack/type.hpp

@@ -42,12 +42,13 @@
 #include "adaptor/cpp11/unordered_map.hpp"
 #include "adaptor/cpp11/unordered_set.hpp"
 
-#if __cplusplus >= 201703
-
+#if MSGPACK_HAS_INCLUDE(<optional>)
 #include "adaptor/cpp17/optional.hpp"
-#include "adaptor/cpp17/string_view.hpp"
+#endif // MSGPACK_HAS_INCLUDE(<optional>)
 
-#endif // __cplusplus >= 201703
+#if MSGPACK_HAS_INCLUDE(<string_view>)
+#include "adaptor/cpp17/string_view.hpp"
+#endif // MSGPACK_HAS_INCLUDE(<string_view>)
 
 #endif // defined(MSGPACK_USE_CPP03)
 

include/msgpack/v1/cpp_config_decl.hpp

@@ -128,4 +128,10 @@ MSGPACK_API_VERSION_NAMESPACE(v1) {
 
 #endif // MSGPACK_USE_CPP03
 
+#if defined(__has_include)
+#define MSGPACK_HAS_INCLUDE __has_include
+#else  // defined(__has_include)
+#define MSGPACK_HAS_INCLUDE(header) 0
+#endif // defined(__has_include)
+
 #endif // MSGPACK_V1_CPP_CONFIG_DECL_HPP