That approach only works if the string isn't being mutated in a way which could change its size, though. Otherwise you need to make sure it has a lexical lifeti

That approach only works if the string isn't being mutated in a way which could change its size, though. Otherwise you need to make sure it has a lexical lifetime (and be very careful with it), or if that's not possible pay the double alloc cost. I would be also worried about any difficulties separating the length and data causes for prefetching/cache lines though. The second form is also more amenable to SSO; I'm not sure how often that would come up in the kernel but it's saved me a decent chunk of memory in at least one past project. (Still today I'm sometimes frustated by Go `string` porting from Java `String`, like great now I don't have to pay a boxing overhead but if it's often absent/empty my base size is now 2x what it would otherwise be...)