> The code to handle the special cases of invalid inputs can sometimes have dramatic effects on code size and performance, sometimes too much to bear for code that should never run in the first place; allowing for garbage output to be produced for garbage input instead of a result that says "this is garbage input" could well be acceptable.
That seems solvable by refactoring your types a little. Also, some languages do not allow partial functions - such as total functional programming languages.
> we have yet to find a satisfying specification for data races that is more constraining than "anything goes," and the two most well-known attempts (Java and C++) have both been widely regarded as failures.
What about nested data parallelism[1] or pure parallelism such as in Haskell?
[1] https://www.classes.cs.uchicago.edu/archive/2016/winter/3200...
Would pointer provenance still be such a big deal if one-past-the-end pointers were disallowed? All the interesting examples I’ve seen are based on one-past-the-end pointers.
I assume something analogous could happen with pointers to freed memory that are converted to integers, but that seems easier to resolve.
Because maybe you're specifying a partial function. The code to handle the special cases of invalid inputs can sometimes have dramatic effects on code size and performance, sometimes too much to bear for code that should never run in the first place; allowing for garbage output to be produced for garbage input instead of a result that says "this is garbage input" could well be acceptable.
Furthermore, there are some places where we don't actually know how to specify the intended behavior in the first place. Data races are perhaps the best example here; we have yet to find a satisfying specification for data races that is more constraining than "anything goes," and the two most well-known attempts (Java and C++) have both been widely regarded as failures. But pointer aliasing is another area that proves surprisingly difficult: if requiring pointer provenance isn't acceptable, then trying to come up with a reasonable specification is surprisingly difficult.