Given()

given=()

[omerta pants (kwlzn/snapshot_tmp)]$ ag -i rule | wc -l
     803
[omerta pants (kwlzn/snapshot_tmp)]$ ag -i directive | wc -l
       4

error[E0277]: the trait bound `std::string::String: std::convert::From<std::io::Error>` is not satisfied
   --> src/rust/engine/src/fs.rs:781:7
    |
781 |       util::safe_create_dir_all(dest_dir)?;
    |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::convert::From<std::io::Error>` is not implemented for `std::string::String`
    |
    = help: the following implementations were found:
              <std::string::String as std::convert::From<&'a str>>
              <std::string::String as std::convert::From<std::borrow::Cow<'a, str>>>
    = note: required by `std::convert::From::from`

error: aborting due to previous error

String

Result<(), String>

?

In case of the Err variant, it retrieves the inner error. try! then performs conversion using From. This provides automatic conversion between specialized errors and more general ones. The resulting error is then immediately returned.

From

self.x = y

./pants clean-all test blah

Cell

RefCell

map_err(|e| ...)?

fn?

Result

Result

map_err

RefCell

Mutex

pub struct Snapshots {
  ..
  temp_dir: TempDir,
  next_temp_id: atomic::AtomicUsize,
}

pub struct Snapshots {
  ..
  temp_generator: Mutex<(TempDir, usize)>
}