compiling all tests after some reorganization

test/set/function_set_pre_pre_error.cpp

@@ -0,0 +1,14 @@
+
+#include <boost/contract/free_function.hpp>
+
+// Test pre cannot be set twice for free functions
+// (member functions use same setter objects, so no need to test those too).
+
+int main() {
+    auto c = boost::contract::free_function()
+        .precondition([&] {})
+        .precondition([&] {}) // Error.
+    ;
+    return 0;
+}
+