Passing function pointer from Rust to C++
diff --git a/tests/ffi/tests.cc b/tests/ffi/tests.cc
index 6384ac1..4aad3a2 100644
--- a/tests/ffi/tests.cc
+++ b/tests/ffi/tests.cc
@@ -92,6 +92,10 @@
   }
 }
 
+void c_take_callback(rust::Fn<size_t(rust::String)> callback) {
+  callback("2020");
+}
+
 void c_try_return_void() {}
 
 size_t c_try_return_primitive() { return 2020; }