Heh, I can especially tell the first code example is LLM-generated. Humans don't usually write comments like:

   // There are a few ways to let API callers bring their own 
   // memory, as they would in a no-malloc environment and this
   // stack-friendly c'tor is a stand-in for that. 

There's just something about this comment that doesn't feel right. I've seen these kinds of phrasings in LLM output before but I'm not sure exactly how to describe them.