It's deterministic, but it's still a heuristic in the sense that it's a guess at the underlying intent of the code. You can come up with different, perhaps simp

It's deterministic, but it's still a heuristic in the sense that it's a guess at the underlying intent of the code. You can come up with different, perhaps simpler guesses, but they're still guesses. It's quite common in existing real-world C code to rely on the ability to fill in a variable via a pointer of one type and then access it via a pointer of another type, and you expect the language to properly return the data you wrote to that pointer. The C committee determined that, just about always, that happens when one of the pointers is a char pointer (e.g., you call read() or write() on a struct), and they said that char pointers are allowed to alias by default but others can't. That's their guess, which is mostly accurate. There are much nicer answers here if you're not obligated to be compatible with existing C code - but in that case, especially today, I'd go with one of several other languages that can accurately express intention at the source code level instead of making backwards-incompatible changes to C. :)