Confusing error message

[jthornber]

A spurious semicolon meant this function was returning () rather than some form of io::Result. I feel the error message could have been more helpful, since the type was just plain wrong, rather than inadequately specified.

use std::fs::File;
use std::io;
use std::os::unix::io::AsRawFd;
use std::path::Path;

pub struct DMIoctl {
// FIXME: automate closing the fd
control_file: File

}

static IOCTL_CONTROL_PATH: &'static Path = Path::new("/dev/mapper/control");

impl DMIoctl {
fn new_specifying_control<P: AsRef>(path: &P) -> io::Result {
let i = DMIoctl { control_file: try!(File::open(path)) };

   // main.rs:21:9: 71:11 error: unable to infer enough type information about `_`; type annotations or generic parameter binding required\

[E0282]
//main.rs:21 Ok(i);
^~

   Ok(i);

}

fn new() -> io::Result {
Self::new_specifying_control(IOCTL_CONTROL_PATH);
}
}

[TimNN]

Duplicate of #24889.

Also, @jthornber you can get better code formatting by surrounding your code like this:

```rust
// your code goes here
```

That example would then render as

// your code goes here