error[E0277]: the trait bound `Option<&str>: AsRef` is not satisfied --> $DIR/issue-72442.rs:12:36 | LL | let mut f = File::open(path.to_str())?; | ---------- ^^^^^^^^^^^^^ the trait `AsRef` is not implemented for `Option<&str>` | | | required by a bound introduced by this call | note: required by a bound in `File::open` --> $SRC_DIR/std/src/fs.rs:LL:COL error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.