volatile is a type qualifier and can be casted. However, memset's declaration takes a void* which prevents you from passing a volatile void*. casting or not wo

volatile is a type qualifier and can be casted. However, memset's declaration takes a void* which prevents you from passing a volatile void*. casting or not won't change anything in this case because what matters is what memset takes and not what the pointer's fully qualified type is prior to calling memset. From the compiler's perspective, you're passing a non-volatile pointer to memset which makes it a candidate for elimination if the pointer's lifetime ends after memset call.