please clang and gcc10

diff --git a/include/simgrid/s4u/Activity.hpp b/include/simgrid/s4u/Activity.hpp
index 5f3999f..e379e4d 100644 (file)
--- a/include/simgrid/s4u/Activity.hpp
+++ b/include/simgrid/s4u/Activity.hpp
@@ -9,6 +9,7 @@
 #include "xbt/asserts.h"
 #include <atomic>
 #include <simgrid/forward.h>
+#include <string>
 #include <xbt/signal.hpp>
 
 namespace simgrid {