Stop including string content in index panics?

ConradIrwin:

or forbid indexing into a string - doesn't seem tenable

You should be able to ban slicing with clippy:

rust-lang.github.io

char_indices - Clippy Lints

Checks for usage of items through absolute paths, like std::env::current_dir. | A collection of lints to catch common mistakes and improve your Rust code.