Hi,

regex::Regex::new("a{\r\n");

will cause

thread 'main' panicked at 'index out of bounds: the len is 1 but the index is 1'

playground

I found it while porting https://github.com/rust-fuzz/targets to afl.rs and honggfuzz (it's currently only using libFuzzer).
It's funny because libFuzzer seems unable to find it while honggfuzz finds it reliably in just a couple of seconds and AFL in a couple of dozen of minutes.

Regexes sometimes are built from untrusted input so I guess it could be used for denial of service.

@robertswiecki : I found it with honggfuzz first, is that trophy worthy?