Improper Regex::replace behaviour

[ConnorGray]

The regular express ((IMG|CAM|MG|MB2)_|(DSCN|CIMG))(?P<n>[0-9]+)$ is a match on the text "CIMG2341" but expected result of regex.replace("CIMG2341", "$n") returns "2341" is not found, instead "CIMG2341" is returned. The correct behavior is observer when the original regex is replaced with ((MG|MB2)_|(DSCN|CIMG))(?P<n>[0-9]+)$.

extern crate regex;

use regex::{Regex};

fn main() {
    let text = "CIMG2341";

    let regex = Regex::new(
        "((IMG|CAM|MG|MB2)_|(DSCN|CIMG))(?P<n>[0-9]+)$").unwrap();

    assert!(regex.is_match(text)); // This works (no panic)

    let renamed = regex.replace(text, "$n");
    assert_eq!(renamed, "2341"); // This panics
}

[mbrubeck]

This is a regression from 6300490 (#290).

[BurntSushi]

@ConnorGray Thanks again for the bug report! This should be fixed in regex 0.1.80 and regex-syntax 0.3.9 on crates.io.

[ConnorGray]

@BurntSushi Thanks again for the quick fix!