```
However because `offset` is marked as a GEP inbounds instruction, this will tell
-llVM that ptr is allocated and won't alias other allocated memory. This is fine
+LLVM that ptr is allocated and won't alias other allocated memory. This is fine
for zero-sized types, as they can't alias anything. However if we're using
heap::EMPTY as a sentinel for a non-allocation for a *non-zero-sized* type,
this can cause undefined behaviour. Alas, we must therefore special case either