[insanitybit]

I think the short answer is "trivial in some cases, impossible in others". It's almost certainly possible that your compiler could inspect every allocation and tag each pointer with it internally. The problem comes with everything else - once you add loops and conditionals the length of that pointer can be all over the place. You'd basically need a symbolic executor tracking every pointer.

There are some big issues with this:

1. It's slow. Symbolic execution involves the interpretation of your program.

2. It would be imperfect and you'd likely have false positives.

3. It would likely be incomplete - for example, how would you handle the situation of only having a header?

So it's a good idea but it's very hard to make practically useful.