rustc panics with: assertion failed: match *region { ty::ReLateBound(..) => false, _ => true, }

[tuxmark5]

This code snippet causes rustc to panic:

fn trim_lines(text: &str) -> impl Iterator<Item=&str> {
    let mut prefix_length = 0;
    for c in text.chars() {
      match c {
        ' ' => prefix_length += 1,
        '\n' => continue,
        _ => break,
      }
    }

    text.lines().map(|line| {
      if line.len() >= prefix_length {
        &line[prefix_length..]
      } else {
        line
      }
    })
  }

fn main() {
  trim_lines("hello");
}

Meta

rustc 1.23.0-nightly (33374fa 2017-11-20)
binary: rustc
commit-hash: 33374fa
commit-date: 2017-11-20
host: x86_64-unknown-linux-gnu
release: 1.23.0-nightly
LLVM version: 4.0

The same thing happens with 1.24 nightly too on rust playground.

[arielb1]

Duplicate of #42479