Not being able to exhaustively test simple problem absolutely means you can't exhaustively test massively more complex problem. For a monotonically increasing function f, which I think we can agree a function mapping from the size of the input set to the runtime of an exhaustive execution of all elements in the set qualifies as, if |small| < |large| then f(small) < f(large). Therefore if f(small) is too big then f(large) is definitely too big.
> Not being able to exhaustively test simple problem absolutely means you can't exhaustively test massively more complex problem.
"Simple"/"complex" doesn't necessarily imply "small"/"large", respectively. Testing whether the Collatz conjecture holds is "simple", but its search space is (potentially) infinitely large. Testing correctness of concurrent data structures is (probably) a more "complex" problem, and yet it's still possible to perform exhaustive tests of their functionality [0].
In the end, the practicality of exhausting the 64-bit integer search space is irrelevant since it says nothing about the size of the write + checkpoint search space. I could just as easily say that it's easy to exhaust the 16-bit integer search space, but that doesn't mean exhaustively testing for this particular bug is easy.
Just because you can't exhaustively test one thing doesn't mean you can't exhaustively test anything.
Not being able to exhaustively test simple problem absolutely means you can't exhaustively test massively more complex problem. For a monotonically increasing function f, which I think we can agree a function mapping from the size of the input set to the runtime of an exhaustive execution of all elements in the set qualifies as, if |small| < |large| then f(small) < f(large). Therefore if f(small) is too big then f(large) is definitely too big.
> Not being able to exhaustively test simple problem absolutely means you can't exhaustively test massively more complex problem.
"Simple"/"complex" doesn't necessarily imply "small"/"large", respectively. Testing whether the Collatz conjecture holds is "simple", but its search space is (potentially) infinitely large. Testing correctness of concurrent data structures is (probably) a more "complex" problem, and yet it's still possible to perform exhaustive tests of their functionality [0].
In the end, the practicality of exhausting the 64-bit integer search space is irrelevant since it says nothing about the size of the write + checkpoint search space. I could just as easily say that it's easy to exhaust the 16-bit integer search space, but that doesn't mean exhaustively testing for this particular bug is easy.
[0]: http://demsky.eecs.uci.edu/publications/c11modelcheck.pdf