There were/are absolutely plenty of real problems with the resulting code pointed out. Running Miri trivially found soundness issues, `SAFETY` comments that demonstrate that the model in question fundamentally doesn't understand/simulate understanding how unsafe rust works [0], etc.
[0] https://github.com/oven-sh/bun/blob/fc865b398e51de8a95ddde4b...
These seem really easy to address. Any SAFETY comment that relies on the caller is something you can trivially find and fix.
First, we're talking about a massive rewrite of complex software project which no one has fully reviewed and which the people most familiar with the code base (the bun maintainers) aren't even qualified to do so. As such, the issues people have found are mostly surface level.
But second, you're right, this is an easy thing to search for (especially with LLMs). And yet, the example I linked has been there since may, surviving multiple rounds of review. From this, we can draw a few conclusions: 1) claude (including apparently mythos/fable) fundamentally doesn't "understand" how unsafe rust works, and 2) no one on the bun team is aware that they need to tell it to fix this (if they're even aware that this isn't allowed in the first place).
The reason such trivial defects in a codebase are a red flag isn't so much those specific issues themselves, it's what they reveal about the authors. If you find a lot of obvious defects in some code, it's very likely that there are also many more subtle harder to detect issues as well.
I think that's an interesting point that the models wrote SAFETY comments that are so obviously not what SAFETY comments are for. A SAFETY comment can never be about callers, that's the whole point of `unsafe`.
Look a few more till you find absolutely bs SAFETY comments marked on immediate UBs. They are everywhere.