[throwaway2037]

    > Careless recursion in C... is obviously bad

Keeping the focus specifically on this bug: Do you think it was "careless recursion" in libexpat? That library was started in 1997, and the recursion bug wasn't found until 2022.

    > Another way is to be absolutely restrictive, rather than track the limit. Create some test cases representing the worst recursive cases you're willing to handle (and document as such). Empirically measure their stack use. Multiply that by 1.5 and use that as the stack check limit.

We look forward to your patches for libexpat to add new unit tests.