In my experience, all Clippy does is find style issues. Perhaps it's more effective in other projects, but in the code I wrote all by myself it didn't find a single error (as in bug). That's not to say Clippy isn't useful. I value style consistency (in this case consistency among the general pool of all Rust programmers and not inside a single project). Of course, YMMV.

> For off by 1 errors, in Rust it’s often better to turn to iterators where appropriate than to say using indexes (it’s also more efficient in most cases).

The off-by-one errors I made weren't related to indexing collections. I don't remember anymore what it was exactly, it got caught by the very first tests I wrote before even trying to use anything. I do use iterators whenever they make sense and I write new iterators whenever it makes sense. Still, good note from you.