The best way is to make sure it's correct to every test case you can find. I.e. include the test s you point to there along with the tests from libiberty etc.

The best way is to make sure it's correct to every test case you can find. I.e. include the test s you point to there along with the tests from libiberty etc. That'll at least let you say that's it's as provably correct as the others. The next advantage is going to be that Rust helps prevent certain classes of bugs (in this case memory issues) as long as you're not doing unsafe{} things. And while that rests on Rust's ability to prove that it's a step up from not having that. The handwritten parser doesn't mean much in the advent of testing against a wide array of inputs, if it was parsing incorrectly then it's not going to pass the tests. Sure there might be an edge case where it just recurses but that's also the case of libcxxabi and the others. The code being longer also means basically nothing. It just means that either the code is more verbose or could be shortened somehow it says nothing about it's correctness or viability.