The author argues that if rewriting a C++ codebase in Rust makes it more memory-safe, that's not because Rust is memory-safe. What?
replies(4):
Because it's a re-write, you already know all the requirements. You know what works and what doesn't. You know what kind of data should be laid out and how to do it.
Because of that, a fresh re-write will often erase bugs (including memory ones) that were present originally.
The observation is that second implementation of a successful system is often much less successful, overengineered, and bloated, due to programmer overconfidence.
On the other hand, I am unsure of how frequently the second-system effect occurs or the scenarios in which it occurs either. Perhaps it is less of a concern when disciplined developers are simply doing rewrites, rather than feature additions. I don't know.