Multiline strings with carriage return - unknown string escape

[adam-frisby]

Using Windows style (or Mac OS 9) style line endings results in "unknown string escape: \r" when attempting to use a multiline string literal.

test.rs:2:26: 2:27 error: unknown string escape: \r
test.rs:2   let string = ~"This is \
                                    ^

fn main() {
    let string = "This is \
                  a test";
}

When cloning a rust library, git automatically converted the Linux style line endings to Windows which caused compilation to fail.

[SiegeLord]

Discussion in #7946 seems relevant, although it only directly relates to CR-only line endings. The Rust repository specifically disables that feature of git via .gitattributes (see #9214) which is something one could do in the meantime/if this issue is determined to be a non-issue.

[huonw]

It would be good to at least special case this to emit a more useful error message, even if it's not legal.