single_char_pattern doesn't recognize scape sequences

[gnzlbg]

Example (playground):

string.find("\"");

errors with

  |
3 |     string.find("\"");
  |                ^^^^ help: try using a char instead: `'\"'`
  |
  = note: #[warn(single_char_pattern)] on by default
  = help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#single_char_pattern

However, the appropriate char to use is '"' without the escape: \.

[ghost]

The question is whether Clippy should use '"' over '\"' in suggestions.

It looks like the stdlib prefers the redundant escape form:

fn main() {
    println!("{:?}", '"');
    println!("{}", '"'.escape_debug());
    println!("{}", '"'.escape_default());
}

produces

'\"'
\"
\"

If '"' is better, we should also have a style lint for recommending '\"' to '"'.