add missing include (only for osx?)

diff --git a/src/surf/surf_interface.hpp b/src/surf/surf_interface.hpp
index cdd4d58..a013167 100644 (file)
--- a/src/surf/surf_interface.hpp
+++ b/src/surf/surf_interface.hpp
@@ -7,6 +7,7 @@
 #define SURF_MODEL_H_
 
 #include <cstddef>
+#include <string>
 
 #include <xbt.h>
 #include <memory>