How does your compiler manages to perform lifetime check? What if I save a pointer allocated from an arena somewhere, so it outlives it? What if I forgot to fre

How does your compiler manages to perform lifetime check? What if I save a pointer allocated from an arena somewhere, so it outlives it? What if I forgot to free memory via defer? What about spatial memory safety? Can I read/write outside allowed memory by misusing pointer arithmetic? What about concurrent access? What if a pointer to some piece of memory is invalidated by some other code?