c++ - Does this cause undefined behavior? -

address sanitizer complaining.

struct x {   iterator begin();   iterator end(); };  x foo();  const x& bar(const x& x) {   return x; }  boost_foreach(const auto& xitem, bar(foo())) {   //use xitem } 

yes. foreach happening on reference struct has been created foo call, , gone out of scope after being passed through bar()