fn main() {
    println!("{:?}", {
        std::fs::File::open("foo").map_err(<_>::to_string)
    });
}


/* ~~~~=== stderr ===~~~~
   Compiling playground v0.0.1 (file:///playground)
error[E0631]: type mismatch in function arguments
 --> src/main.rs:5:36
  |
5 |         std::fs::File::open("foo").map_err(<_>::to_string)
  |                                    ^^^^^^^
  |                                    |
  |                                    expected signature of `fn(std::io::Error) -> _`
  |                                    found signature of `for<'r> fn(&'r _) -> _`

error: aborting due to previous error

error: Could not compile `playground`.

To learn more, run the command again with --verbose.

*/

/* ~~~~=== stdout ===~~~~

*/