title: Is undefined behavior worth it?
body: <p>Many bad things happened and continue to happen (or not, who knows, anything can happen) due to undefined behavior. I understand that this was introduced to leave some wiggle-room for compilers to optimize, and maybe also to make C++ easier to port to different platforms and architectures. However the problems caused by undefined behavior seem to be too large to be justified by these arguments. What are other arguments for undefined behavior? If there are none, why does undefined behavior still exist?</p>
  
  <p><strong>Edit</strong> To add some motivation for my question: Due to several bad experiences with less C++-crafty co-workers I have gotten used to making my code as safe as possible. Assert every argument, rigorous const-correctness and stuff like that. I try to leave as little room has possible to use my code the wrong way, because experience shows that, if there are loopholes, people will use them, and then they will call me about my code being bad. I consider making my code as safe as possible a good practice. This is why I do not understand why undefined behavior exists. Can someone please give me an example of undefined behavior that cannot be detected at runtime or compile time without considerable overhead?</p>