Question

Does C++ standard guarantee that here would be no crash when returning auto_ptr‘s payload by value from the function:

class Foo { ... };

std::auto_ptr<Foo> createFoo() { 
  return std::auto_ptr<Foo>(new Foo(...));
}
...
Foo getFoo() {
  std::auto_ptr<Foo> foo(createFoo());
  return *foo; /// would be here a crash?
}

/// main
const Foo& foo(getFoo());

What’s going here accordingly to the standard: *foo is copied, then foo is destroyed and finally return is performed? Or there is an another order of steps?

I tested this example with GCC and there is no crash but I am not sure that it would work with another compilers.

Answer 1

It is very strange code, but, yes – it is guaranteed. There is no RVO, or move semantics, so it should be ok.